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  3. Advanced collagen nanofibers-based functional bio-composites for high-value utilization of leather: A review

Advanced collagen nanofibers-based functional bio-composites for high-value utilization of leather: A review

This review describes how UFL will expand the scope of applications and significantly improve the ontological value of natural leather. Significantly, UFL is expected to boost the sustainable development of conventional leather industry and the next-generation of advanced functional bio-based materials. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 Contents lists available at ScienceDirect Journal of Science: Advanced Materials and Devices journal homepage: www.elsevier.com

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Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 Contents lists available at ScienceDirect Journal of Science: Advanced Materials and Devices journal homepage: www.elsevier.com/locate/jsamd Review Article Advanced collagen nanofibers-based functional bio-composites for high-value utilization of leather: A review Youyou Wang a, b, 1, Manhui Zheng a, b, 1, Xinhua Liu a, b, c, *, Ouyang Yue a, b, Xuechuan Wang c, **, Huie Jiang a, b a College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Wei Yang District, Xi'an 710021, Shaanxi, China b National Demonstration Center for Experimental Light Chemistry Engineering Education, Shaanxi University of Science & Technology, Weiyang District, Xi'an 710021, Shaanxi, China c Institute of Biomass & Functional Materials, Shaanxi University of Science & Technology, Weiyang District, Xi'an 710021, Shaanxi, China a r t i c l e i n f o a b s t r a c t Article history: Natural leather with outstanding biomimetic properties is the main application of animal skin. However, Received 10 October 2020 the traditional tannery industry is facing serious issues of sustainability, such as low value addition and Received in revised form high environmental pollution. Upscaled functional leather (UFL) inherits all the natural properties of 21 January 2021 leather and combines it with other cross-domain functions, due to which it has gained considerable Accepted 3 February 2021 Available online 13 February 2021 attention as advanced functional bio-based materials. This review briefly introduces the multi- hierarchical structure and preponderant properties of leather as a natural biomass. Further emphasis is on UFL, which includes electromagnetic (EM) wave absorbing leather, infrared absorbing leather, X-ray Keywords: Functional leather shielding leather, flexible conductive leather, flame-retardant leather, antibacterial leather, self-cleaning Biomass leather as well as water-, oil-, and soil-repellent leather. Furthermore, the fabrication methods of these Bio-based materials UFLs, their merits and their respective applications are comprehensively discussed. Moreover, possible Sustainability challenges and outlooks for the development of UFL are proposed. This review describes how UFL will expand the scope of applications and significantly improve the ontological value of natural leather. Significantly, UFL is expected to boost the sustainable development of conventional leather industry and the next-generation of advanced functional bio-based materials. © 2021 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by- nc-nd/4.0/). 1. Introduction [2]. Leather products have always played an important role in the lives of humans. According to reports, leather production would Animal skin is a byproduct of meat industry, which is further reach 19 billion square feet in 2020 globally and, hence, leather processed into leather by employing a series of physical, chemical, industry holds a lot of promise. Leather is a unique material pos- and mechanical methods [1]. Manufacturing of leather has been sessing many properties [3], like softness, air and water vapor one of the earliest activities of mankind. By the end of the Neolithic permeability, good hygroscopicity and wearability, flexibility, period, people in the eastern Mediterranean region started using genuine and unique beauty, etc. Moreover, it possesses the ad- leaves, fruits, rhizomes, and other plant materials to process animal vantages of biomass materials, such as biodegradability and skins and transformed them into more durable and useful materials excellent biocompatibility. This is in contrast to polymer substrates with inferior mechanical properties and wearability, which can potentially cause damage to the environment owing to their poor * Corresponding author. College of Bioresources Chemical and Materials Engi- biodegradability. Leather is used not only for manufacturing neering, Shaanxi University of Science & Technology, Wei Yang District, Xi'an products of daily use, like clothes, shoes, bags, decorative articles, 710021, Shaanxi, China. etc. [4], but it is also shifting its focus towards functional materials. ** Corresponding author. However, with increased impetus on environmental protection E-mail addresses: liuxinhua@sust.edu.cn (X. Liu), wangxc@sust.edu.cn (X. Wang). world-wide, wastewater, sludge, and solid waste from tannery have Peer review under responsibility of Vietnam National University, Hanoi. gradually become the three technological bottlenecks for sustain- 1 Youyou Wang and Manhui Zheng contributed equally to this work. able development of leather industry. The cost of leather https://doi.org/10.1016/j.jsamd.2021.02.001 2468-2179/© 2021 The Authors. Publishing services by Elsevier B.V. on behalf of Vietnam National University, Hanoi. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
  2. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 production increases greatly while tackling these eco- In addition, special functional materials can be compounded along environmental issues, making the traditional leather industry with tanning agents, retanning agents, or fatliquoring agents dur- challenging. It is crucial for the leather industry to significantly ing leather processing, to prepare corresponding functional leather. enhance the value of the resultant leather products along with Herein, we briefly introduce the multi-hierarchical structure ensuring environmental safety. and properties of leather, taking into account the histological and With developments in science and technology and improve- structural characteristics of natural collagen and animal skin. The ment in the standard of living, leather processing has become review mainly focuses on the existing functional and natural cleaner and more eco-friendly [5,6]. Basic properties of leather leathers, prepared from animal skins as raw bio-based materials. products, such as fullness, air permeability, cold resistance, flexural Novel functional leathers, such as electromagnetic (EM) wave strength, etc., have been improved. Owing to a large variety of shielding leather [12], thermal camouflage leather [13], X-ray species, different outputs and functionality, there are various types shielding leather [14] and conductive leather for smart devices [3], of functional leathers. Recently, materials with advanced functions flame retardant leather, antibacterial leather, self-cleaning leather, have become more popular, due to their conductivity, flame have been explored. Moreover, conventional functional leathers, retardancy, self-cleaning property, antibacterial property, electro- such as waterproof, anti-fouling, and oil-proof leather have also magnetic shielding effectiveness, wave absorptivity, and X-ray made a lot of progress. With developments in UFL, the scope of shielding ability. Functional leathers such as conductive leather, applications of leather will further expand and there will be a flame retardant leather, self-cleaning leather, antibacterial leather, dramatic increase in the ontological value of natural leather waterproof leather, anti-fouling leather, oil-proof leather, electro- biomass. Significantly, functional leather will boost the sustainable magnetic shielding leather, thermal camouflage leather, and X-ray development of conventional leather industry and also of next- shielding leather have been successfully developed by combining generation advanced functional bio-based materials. with other functional materials. Functional leather is prepared using conventional processing techniques, wherein functional 2. Multi-hierarchical structure and properties of skin chemicals with specific properties are added either during pro- cessing or finishing of leather. The functional materials are either Leather, a natural bio-product with multi-layered hierarchical linked to the active groups of collagen fibers in leather or directly structure, has been in focus since a long time. Indeed, leather is mixed with materials such as film-forming agents for leather fin- derived from natural collagen, which is an elementary building ishing. They remain on the leather by forming chemical linkages or block of collagen-rich tissues. The conformation of natural collagen by physical adhesion and impart specific functions to the resultant that accounts for more than 50% of the skin, includes five hierar- leather with. For example, flame retardancy is imparted during chical structures: primary structure (amino acid triplet), secondary leather processing of flame retardant leather [7e9]. Moreover, structure (a-helix), tertiary structure (triple helix), quaternary conductive material is added to produce conductive leather [10,11]. structure (fiber), and supramolecular aggregation, based on the Fig. 1. Schematic diagram showing the histological structure of animal skin (1). Reproduced with permission [16]. Copyright © 1969, Springer Nature. Illustration of the multi- hierarchical structure of nature collagen (2), Reproduced with permission [17]. Copyright © 2019, Elsevier Science B.V. 154
  3. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 biosynthesis and in vivo assembly processes of collagen into its makes it diversely functional. In addition to the basic functions of hierarchical fibrillar architectures [15], which are shown in Fig. 1. typical biomass materials, such as excellent biodegradability and Type I collagen, which is mainly present in animal skin, pos- biocompatibility, it also has good mechanical properties, thermal sesses three a chains. Each chain consists of more than 1000 amino stability, is hygienic, and shows wear resistance. The multi- acid residues, with repetition of permutations along the entire hierarchical structure makes it possible to impart it with multiple chain and having proline and hydroxyproline in a higher propor- functions by regulating its structure. tion. Proline is conformationally metastable, due to which the abundant number of Gly-Pro-Hyp (Gly ¼ glycine, Pro ¼ proline, 3. Functional leather Hyp ¼ hydroxyproline) triplets in collagen triple helices, confer it with well-defined flexibility [17]. Therefore, the alignment of Gly- 3.1. EM wave absorption leather (EMI shielding materials) Pro-Hyp triplets within the fibrillar structure provides flexibility to the fibrils [18]. Meanwhile, the secondary bonds formed between As a result of high increase in emissions from antenna and peptide chains, as well as the intramolecular and intermolecular electronics equipment, EM radiations have become a matter of covalent bonds formed by aldol condensation, aldolamine concern. EMI shielding materials are essential for solving the condensation, and aldol histidine crosslinking reactions between problem of EM pollution [23,24]. This has led to intensive research the collagen molecules, stabilize the natural triple-stranded in materials related to EMI shielding, such as carbon-based polymer conformation. Hence, natural collagen has a very high tensile nanocomposites [25], novel metallic materials [26], MXene-based strength and structural stability [19,20]. It should be noted that the materials [27], etc. The main mechanisms of shielding of EM basic tissue structure of natural collagen is collagen bundles [21]. waves are reflection, absorption, and multiple reflections [28]. These collagen bundles interpenetrate and intertwine into one Conductive metals such as silver, gold, and copper have the ability another to form a three-dimensional network, imparting the to reflect EM waves, whereas ZnO, SiO2, and TiO2 with high leather with outstanding mechanical properties [17]. Furthermore, dielectric constants, have the ability to absorb EM rays. Moreover, this dense felt work of collagen at a macro level endows the porous foams and functional polymer nanocomposites with large rawhide and its products (leather) with special mechanical prop- interfaces have the ability to shield EMI through multiple re- erties [22], good air permeability, flexibility and water vapor flections [29]. Lightweight, foldable, and conductive composite permeability. In fact, owing to the multi-hierarchical structure of paper for EMI shielding, has been researched [30]. Leather, which is collagen, the hierarchical organization at any structural level of usually worn and decorated, can also be used to prepare EMI collagen material allows for the intervention and interplay of a shielding materials. A comparison of the preparation methods and series of design features, which is very significant for specific ap- performances of different EMI shielding materials is summarized in plications. All in all, the multi-layer structure of natural leather Table 1. Table 1 Typical examples of EMI based on different materials. EMI shielding Key components Preparation method Shielding Features Disadvantages Ref. materials effectiveness (dB) MXene aerogel/ Nature wood-derived Freeze-dried and ~71.3 dB Ultra-light, green and Poor wearability [31] WPC composites porous carbon (WPC) annealed efficient skeleton 3D MXene aerogel Hybrid aerogel film Strong aramid nanofibers Facial blade coating and ~54.4 dB Hydrophobicity Poor wearability [32] of FC-ANF/CNT (ANF) freeze-drying Self-cleaning Poor mechanical films Conductive carbon Exceptional Joule heating properties nanotubes (CNT) performance Poor shielding effect Hydrophobic fluorocarbon (FC) resin EMA/K-CB Ketjen carbon black (K-CB) Dropwise K-CB solution ~33.9 dB Low percolation threshold Poor mechanical [33] composites Ethylene methyl acrylate to the EMA solution properties copolymer (EMA) Metallic nanomesh Single-layer metallic Ultraviolet lithography >40 dB High transmittance (85% at Not light enough and [34] nanomesh (Cu, Cr) and the ion beam 550 nm) inflexible A transparent dielectric etching technique Wide broadband range (0.5 substrate (glass) e40 GHz) PANI-based Polyethylene terephthalate In-situ polymerization ~23.95 dB Bending durability (10,000 Poor shielding effect [30] composite paper (PET) paper polyaniline deformation cycles) (PANI) MXene-decorated MXene nanosheets Spray-drying ~36 dB Joule heating, strain sensing Poor shielding effect [35] fabrics Plain weave cotton fabrics performance Flexibility and breathability EMI materials Natural collagen fibers Thermal treatment 36e57 dB Lightweight Poor mechanical [36] based on Ferromagnetic Low-cost properties. collagen fibers nanoparticles (NPs) Flexible Skin collagen fiber (CF) Electroplated ~31.0 dB [37] NieFeeP coating EM waves LM Coating MNPs onto LM 4.58 wt % of coated Lightweight May slightly affect the [12] absorption Metal NPs (MNPs) MNPs Excellent processability texture of leather leather 76.0 dB Flexibility and breathability LM Spaying Cu@Ag 5.17 v% of Cu@Ag High-performance [38] Cu@Ag nanoflakes nanoflakes on LM nanoflakes Wearable 100 dB 155
  4. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 Table 1 shows that compared to other EMI shielding materials, systems or human bodies to comply with special technical re- leather-based materials possess good EMI shielding properties. quirements of stealth. With continuous progress in infrared sur- Additionally, they also inherit the preponderant properties of nat- veillance technologies [42,43], thermal cloaking and camouflage ural leather, such as lightweight, excellent processability, flexibility, have gained much attention [44e47]. The preparation methods and breathability, etc. On one hand, due to their high electrical con- performances of different thermal camouflage materials are ductivity, metal matrix materials can effectively reflect EM rays. On compared and summarized in Table 2. the other hand, leather matrix (LM) is a natural material with Although leather is one of the oldest clothing materials, it is still dielectric properties. It has a hierarchical suprafibrillar structure popular, due to its good flexibility, comfortable wearability, high and abundant number of dipoles, which improve the energy water-vapor permeability, and high mechanical strength. Signifi- dissipation of EM rays [12]. The microstructure containing bundles cantly, the intricacy at each level (nano to micro and macro) in the of 3D collagen nanofibers can significantly induce multiple diffused hierarchy of leather structure has an amazingly strong multiple reflections of EM rays, which dramatically increase the trans- diffuse reflection ability and an efficient insulation property [13]. mission routes of microwaves inside the LM. This promoted the Wang et al. [13] demonstrated the in situ growth of SiO2 NPs on the dipole relaxation-induced dielectric loss to EM microwaves 3D hierarchical leather scaffolds (Fig. 3-(1)(2)), which not only [39e41]. Therefore, metal nanoparticles (MNPs) can be coated on increased the porosity of leather, but could also trap stagnant air as the LM to obtain EMI shielding composite materials that possess a heat insulation material more effectively. In addition, it could also both EM rays absorptivity and reflectivity [12]. This makes it su- prevent the infrared absorbing groups (-NH2) of the leather from perior to conventional polymer matrices that lack dielectric loss absorbing infrared radiation. This improved the infrared reflection ability. For instance, Cu@Ag nano-coating was applied on the sur- ability of leather from hot objects. The prepared multifunctional face of leather to obtain a lightweight, high-performance, and thermal camouflage leather had the advantages of high flexibility wearable EMI shielding leather (Fig. 2) [38]. This coating had good (Fig. 3-(3) a), good hydrophobicity (Fig. 3-(3) h), flame retardancy stability with no obvious cracking after bending 25,000 times. (Fig. 3-(3) i), high porosity, low thermal diffusivity, and thermal conductivity. It can be potentially used in wet environmental con- 3.2. Infrared absorption leather (Thermal camouflage materials) ditions (Fig. 3-(3) (e-g)) and shows an outstanding long-term thermal camouflage performance for human body (Fig. 3-(3) j). Thermal camouflage materials, also known as high-temperature Moreover, it can be tailored into diverse complex patterns with infrared camouflage materials or infrared stealth materials can be intact infrared stealth ability (Fig. 3-(3) (b-d)), endowing leather used to weaken the characteristic signals of infrared weapon with new functions. Fig. 2. (1) Schematic representation showing the lightweight and high-performance electromagnetic radiation shielding composites based on a surface coating of Cu@Ag nano- flakes on a LM. (2) Photos of flexible LM-Cu@Ag samples (10 cm  10 cm) (a), cross-section microstructure of LM-Cu@Ag (b), top view of SEM image of LM-Cu@Ag (c), conductivity of LM-Cu@Ag with different volumetric fractions (0e5.17 v%) of Cu@Ag nanoflakes (d), and the corresponding log value of the conductivity with the threshold of Cu@Ag nanoflakes, fc ¼ 0.41 v% (Inset Fig. 4 (2) d), photos of meter-scaled LM-Cu@Ag (e), the wearable clothing tailored from meter-scaled LM-Cu@Ag (f, g). (3) Hierarchical fibrous structure of the LM (a), SEM images of different levels of microstructure morphology of the LM (bee), propose shielding mechanism of LM-Cu@Ag to microwaves (f). Reproduced with permission [38]. Copyright © 2016, Royal Society of Chemistry. 156
  5. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 Table 2 Typical examples of thermal camouflage based on different materials. Thermal Key components Preparation methods Camouflage performance Features Disadvantages Ref. camouflage materials Wearable Flexible thermoelectric Integrating a layer The metabolic heat from human Adaptive within a wide Complex construction [44] thermal device (TED) [48] skin cannot be seen by infrared range of background Poor wearing comfort camouflage Cloth (fabric) camera in 16e38  C temperature (7 Ce15  C) device Phase change material Thermal conductivity Anti-IR reflection Property (PCM) layer (30 W m2 K1) Wearable High-emissivity elastomer Infrared Paraffin Insitu polymerization Emissivity is 0.575 Better flame retardancy Potential formaldehyde [49] camouflage Urea-formaldehyde Reduce temperatures by 5 Washable hazard fabric resin e10  C Flexibility and bending Fabric resistance Leather SiO2 NPs In situ grown on the (Kirchhoff law) ε ¼ 0.63 Hydrophobicity Slightly affect the [13] thermal Leather fibrous scaffold of Low thermal diffusivity Flame-resistance softness of the resultant camouflage leather (1.24  107 m2 s1) Arbitrary tailorability leather armor Low thermal conductivity Wearable (0.04 W m1 K1) Flexibility Smaller surface temperature difference (DT) Fig. 3. (1) The schematic illustration showing the preparation from (a) leather to (b) leather/SiO2 and (c) SiO2-leather/SiO2, (d) FESEM image showing the cross-section of leather/ SiO2, FESEM images of leather/SiO2 showing the (e) microfiber bundle, (f) microfiber and (g) nanofiber, (h) TEM and (i) HAADF-STEM images of primary nanofiber contained in leather/SiO2, (j) FTIR spectra of cowhide, leather and leather/SiO2.(2) The graphical abstract of the multifunctional thermal camouflage armor by direct editing the natural insulation structure of leather. (3) (a) Photograph of SiO2-leather/SiO2, thermal images of SiO2-leather/SiO2 with different patterns covered on the surface of plastic tanker filled by water with the temperatures of (b) 38  C, (c) 50  C and (d) 72  C, thermal images of hydrophobic SiO2-leather/SiO2 (e) before, (f) ongoing and (g) after water pouring on its surface, (h) the surface wetting behaviors of hydrophobic SiO2-leather/SiO2, (i) photograph of hydrophobic SiO2-leather/SiO2 burning by the flame of alcohol lamp, (j) surface temperature and thermal images of thermal camouflage armor of SiO2-leather/SiO2 dressed by people. Reproduced with permission [13]. Copyright © 2019, Elsevier Ltd. 3.3. X-ray shielding leather (X-ray protection materials) the K or L absorption edges of an element play a major role in the attenuation of X-ray photon energy and have significant attenua- X-rays have been ubiquitously utilized in everyday life and in- tion effect on X-ray photons of similar energy. Therefore, materials dustrial processes. However, long-term exposure to X-rays can with high mass densities (r) and high atomic numbers (Z) are cause biological effects, can directly or indirectly affect human considered to be effective X-ray shielding materials [52]. tissues, and can also have harmful effects on human health [50,51]. Commonly used shielding materials include lead plate, cement, Thus, effective radiation shielding materials protect people from alloy, and lead rubber. However, poor flexibility, high toxicity and excessive exposure to X-rays in an X-ray environment. Generally, high specific gravity result in poor wear-ability. Meanwhile, 157
  6. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 Fig. 4. (1) Graphical abstract of X-ray shielding by Biz@BixLayNL;(2) Photos of foldable and flexible Bi28.2@Bi3.48La3.48NL samples (10 cm  10 cm). Reproduced with permission [55]. Copyright © 2020, American Chemical Society. (3) Graphic illustration of the facile two-step “impregnationdesolvation” strategy for the preparation of the BiINP- LM sample (A). SEM images of LM (B), BiINP-LM (C) and elemental mappings of Bi and I (D). Digital photographs of the as-prepared BiINP-LM (E). Reproduced with permission [54]. Copyright © 2020, American Chemical Society. polymer-based composite materials have low air permeability and address the serious challenges of protection against X-rays softness, which makes it difficult for them to meet the re- (Fig. 4). NL, owing to its multi-layer woven structure and quirements of wearability. porous nature, can achieve multiple attenuation of photon en- Significantly, natural leather (NL) can be considered as a ergy. Various functional groups such as amino and carboxyl prospective material, having many application potentials, to groups can be chemically modified to stabilize elements with Fig. 5. (1) SEM images showing the surface of (a) untreated and treated leathers (b) through single (aniline 0.30 M, APS 0.40 M, HCl 0.20 M, polymerization time 4 h and 5 ± 2  C), (c) double (aniline 0.15 M, APS 0.20 M, HCl 0.10 M, 4 h and 5 ± 2  C) in-situ polymerization of aniline and the corresponding FTIR spectrum (d). (2) Effect of concentration of (a) aniline, (b) oxidant and (c) hydrochloric acid on conductivity and color of treated leathers. (3) Percentage reflectance values against visible wavelength of (a) control and experimental leathers treated with single and double in-situ polymerization of aniline; (b) magnified plot for the experimental leathers treated with single and double in-situ polymerization of aniline. (4) Photos of treated and untreated Sheep Nappa leather. Reproduced with permission [58]. Copyright © 2015, John Wiley and Sons. 158
  7. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 high atomic number. In addition, LM contains some amount of ethylenedioxythiophene), and carbon nanotubes to the surface of moisture, which helps to absorb the heat generated by photons, leather to obtain a capacitive touch screen panel, which displayed thus greatly reducing the aging problem caused by photon ra- good conductivity and working performance. Polypyrrole possesses diations. Furthermore, compared with other X-ray protection high conductivity, is easy to synthesize, has good environmental materials, it has superior flexibility, tailorability, and good stability, and less toxicity and hence can be used to prepare wearability. Thus, Bi/Ce NPs or sodium tungstate can be incor- conductive leather [60,61]. Wegene et al. [3] reported that a coating porated into NL using retanning method to fabricate a novel X- of polypyrrole on leather, prepared by in situ polymerization of ray protection material based on leather [14,53]. Xuepin Liao pyrrole, can simultaneously impart conductivity and color to et al. [54] engineered an advanced leather-based bismuth io- leather. dide nanoparticle-loaded X-ray shielding material (BiINP-LM) employing an “ImpregnationDesolvation” strategy. In short, X- 3.4.2. Flexible sensors, electronic skin (e-skin) ray shielding leather opens up new avenues for wearable X-ray Flexible wearable sensors and electronic skin have a broad range protection materials. of application prospects in personalized health monitoring systems, humanecomputer interactions, and soft robotics [62e68]. 3.4. Conductive leather Currently, a variety of materials have been developed to construct flexible sensors. The preparation methods and performances of 3.4.1. Touch screen gloves different flexible sensors based on various materials are summa- Conductive leather was created for applications in smart or rized in Table 3. From the table (Table 3), it is evident that the as- advanced products. Gloves made of conductive leather can be used prepared flexible leather-based strain sensor shows good perfor- to operate touch-screen devices such as smart phones, iPod, tablet mance in terms of linearity, hysteresis effect, response time, sta- computers, etc. [3,56,57], making their use more convenient. W. bility, and durability. Notably, the homogeneously layered structure Jima Demisie et al. [58] reported the synthesis of self-colored of leather improves the linearity between the electrical signal and (bluish green) and conducting leather by varying the concentra- the strain applied on the leather-based sensor. Therefore, a leather- tions of aniline, hydrochloric acid, and APS (Fig. 5). Hong [59] based sensor having fibrous microstructure, not only possesses applied electrically conductive materials, polyaniline, poly-(3, 4- inherent air permeability, mechanical property, biocompatibility, Table 3 Typical examples of flexible sensor based on different materials. Type Key components Preparation Sensing performance Features Disadvantages Ref. method Response time Calibration curve and recovery time Bio-inspired multi- Collagen aggregates Two-step assembly 110 ms Two linear regions Wearing, Poor mechanical [71] functional sensor Polyaniline and accordingly Degradability, properties Acidified multi-walled gauge factor (GF) carbon nanotube (H- are 10,5.2 MWNTs) CB/leather strain sensor Conductive nanomaterials Filtration Compressive Three linear regions Flexible and stretchable Only suitable [70] carbon black (CB) bending and accordingly GF wearability application for Leather 80 ms are 10.57, 21.49, compressive and Tensile bending 7.29 tensile stress 100 ms Conductive MXene Ethylene glycol (EG) Immersing Not mentioned Two linear regions Self-healing capability Poor mechanical [72] nanocomposite MXene nanocomposite and accordingly GF properties organo-hydrogel hydrogel (MNH) are 5.02,44.85 (MNOH) sensor Ag/PDMS Small silver particles and Physically grinding, 125 ms Three linear regions Multidimensional Detection range is [73] PDMS mixing and accordingly GF sensing relatively narrow are 10,71,550 Weak vibration detecting Paper-based (PB) strain Printing paper Dip-coating Not mentioned Compression and Renewability, Only suitable for [74] sensor CB/CNT/methylcellulose tension strain Biodegradability and low tension or suspension (±0.7%) and low cost compression strain Hydrophobic fumed silica accordingly GF are detection. (Hf-SiO2) suspension 7.5,2.6 Wearable breathable Carbonized metal-organic Dip-coating Response 22 ms Three linear regions Wearable, Complex structure [75] pressure sensor C- framework (C-MOF) Screen printing Recovery 20 ms and corresponding Highly sensitive MOF/PANIF@PU Polyaniline nanofiber sensitivities are Broad-range and (PANIF) 15.81 kPa 1, breathable Polyurethane (PU) sponge 158.26 kPa 1, and 1 Interdigitated electrode- 81.59 kPa coated fabric Multifunctional Leather Filtration 40 ms Two linear regions Flexible Poor washing [10] pressure sensor (a- Nanomaterials acidified and accordingly Wearability performance CNT s/leather) carbon nanotubes (a-CNTs), sensitivities are silver nanowires (Ag- 32.42 kPa1, NWs)) 8.03 kPa1 Interdigitated electrode arrays 159
  8. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 Fig. 6. (1) Schematic of the design principle of leather based e-skin. (2) Leather based display and user-interactive e-skin provide an instantaneous visual response. (a) Structure and (b, c) photographs of leather-based display. (def) Photographs showed that by tuning the applied force from light touch (e) to deep press (f) the brightness of display increased simultaneously. (g) Structure of leather-based user-interactive e-skin. (3) Flexible and wearable pressure sensor based on conductive leather. (a) Schematic illustration of the fabrication procedure of flexible pressure sensor. (b) Photograph of the watchband shaped e-skin directly above the artery of the wrist. (c) SEM image of the cross-section morphology of a-CNTs/leather. (d) A schematic diagram of a-CNT s/leather under different pressures. (e) Current responses to various pressures. SEM images of the surface (f, g) and cross-section (h, i) morphology of a-CNTs/leather at different magnifications. (j) Measurement of the physical force of wrist pulses under normal condition (z72 beats min1). (k) Sensing mechanism: current changes in response to loading and unloading pressure. Scale bars in (c), (g) 500 nm; (f) 2 mm; (h) 200 mm; (i) 1 mm. Reproduced with permission [10]. Copyright © 2018. The Authors published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Fig. 7. (1) Leather morphology by SEM. (A) and (B) grain surface micrographs at 100 and 25,000 magnification, respectively. (C) and (D) cross section micrographs at 2500 and 10,000 magnification, respectively. (2) Elemental analysis of sample: Leather-NaþMMT_6%. (3) SEM magnifications of leather (A, B), leather with 1(C, D), 3 (E, F) and 6 mass% NaþMMT (G, H).(4) Vertical test evaluation of flammability of leather samples with different levels of flame retardants (A) Leather, (B) Leather- NaþMMT _1%, (C) Leather- NaþMMT _3% and (D) Leather- NaþMMT _6%. Reproduced with permission [81]. Copyright © 2014, Elsevier B.V. 160
  9. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 and good wearability of leather, but also displays good 3.5. Flame retardant leather performance. The construction of a leather-based flexible sensor mainly in- As a natural polymeric material, leather itself has certain flam- volves the selection of functional materials, that is, active sub- mability. However, applications of leather for furniture, interior stances. By combining different functional materials with leather, it decoration, aircraft, automotive, etc. require it to have certain is possible to make leather “active” that can repurpose or even flame-retardancy, in order to reduce the possibility of fire. There- outperform the properties of real skin. Carbon materials such as fore, making leather flame retardant is highly important. Flame carbon black, carbon nanotubes, and graphene possess good elec- retardant can be added during leather retanning, finishing, and trical conductivity, high chemical and thermal stability, as well as other processing steps. It can be incorporated into the leather fibers low toxicity. Hence, they can be used as functional materials, which by either physical adsorption or by grafting onto leather by show great application potential in wearable electronics devices chemical bonding to achieve flame-retardancy of the resultant [69]. Huang et al. [70] used leather as a substrate to fabricate a leather. It increased the limiting oxygen index (LOI) and time to strain sensor by filtration of an aqueous dispersion of conductive ignition (TTI), and shortened the flame combustion time [76]. nanomaterials. The surfaces of collagen fiber clusters in the Melamine flame retardant is a nitrogen-based compound, with low multilayer structure of the leather matrix easily adsorb conductive toxicity, low corrosivity, has low smoke generation and high ther- materials and endow it with electrical conductivity. Zou et al. [10] mal stability, and, hence, is an environment-friendly flame retar- reported simple and designable leather based e-skin (Fig. 6), dant material [77]. Yang et al. [78] found that flame retardant fibers wherein leather served as a unique platform for loading acid made by treatment of goat-skin with melamine-based flame treated carbon nanotubes (a-CNTs). Then, the prepared conductive retardant could increase the activation energy and LOI and signif- leather was stitched together with leather-patterned interdigitated icantly improve the thermal stability and flame retardancy of electrode arrays using a sewing machine to fabricate a flexible and leather. Besides, montmorillonite (MMT) also has flame retardancy wearable pressure sensor. [79]. Its mechanism of flame retardancy is mainly manifested in the Fig. 8. (1) Visual comparison of untreated (a) and silver treated natural leather (b). (2) Agar diffusion tests on Escherichia coli and Staphylococcus aureus. (3) SEM analysis of the cross section of silver treated sample at 80 (a) and 1000 (b, c) showing the presence of silver particles under the outer layer. Reproduced with permission [83]. Copyright © 2012, Springer Nature. 161
  10. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 fact that MMT can promote carbon formation and act as a barrier antibacterial leather. Currently, most of the preparation during combustion [80]. G. Sanchez-Olivares et al. [81] added so- methods of antibacterial leather involve the blending of the dium montmorillonite (NaþMMT) during the retanning process of antibacterial agent with finishing agent to make a composite wet blue leather. Owing to the pores and large number of inter- film with antibacterial property. Bao et al. [82] studied the film- stitial voids between fibers (Fig. 7), the NaþMMT particles were forming properties of ZnO/polyacrylate composite emulsions, homogeneously distributed in the leather. Therefore, the flame prepared by physical blending of polyacrylate and zinc oxide retardancy and mechanical strength of leather were simulta- having different morphologies and found that they had excel- neously improved. lent hygienic and anti-bacterial performance, but poor frictional resistance. Pollini et al. [83] could, through an in situ photore- 3.6. Antibacterial leather duction of silver solution, evenly distribute silver clusters, which could well-cover the surface of natural leather and Antibacterial leather is a new type of functional leather improve its abrasion resistance (Fig. 8). Significantly, this inno- having bacteriostatic and bactericidal properties. Antimicrobial vative silver deposition technology on LM is a promising agents are added during the processing of leather or to the method to contain contamination in public transport vehicles. resultant leather. The leather products show bacteriostasis, In addition to the above-mentioned examples, a composite wherein they kill or inhibit the reproduction of bacteria glued coating of positively charged chitosan (CS) and negatively to leather over a certain period of time. Different antibacterial charged gallic acid modified silver NPs (GA@AgNPs) was fabri- agents such as MNPs, photocatalytic antibacterial agents, cated on a leather surface by layer-by-layer assembly with good organic antibacterial agents, natural antibacterial agents, and reusability, which was ideal for antibacterial finishing of dia- composite antibacterial agents can be used for the fabrication of betic leather shoes [84]. Fig. 9. (1) AgeTiO2 NPs and AgeNeTiO2 NPs powders. (2) Self-cleaning effect of AgeNeTiO2 NPs, AgeTiO2 NPs and TiO2 NPs on leather surface exposed to UV and visible light (Orange II (OII), Methylene blue (MB) dyes). (3) The sensitivity test of leather surfaces against Escherichia coli ATCC 25922 (a, b, c) and Staphylococcus aureus ATCC 25923 (d, e, f). B areas are leather surfaces (a, b, d and e samples are treated and c and f are untreated samples) and A areas are medium outside leather surface. Reproduced with permission [89]. Copyright © 2016, De Gruyter. 162
  11. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 Fig. 10. (1) States of a water droplet on the leather surface: (a) untreated, (b) VTES sprayed sample, (c) treated under 50 W for 300s. (2) SPM images of the surfaces of (a) untreated, (b) VTES sprayed and (c) plasma treated leather samples. Reproduced with permission [93]. Copyright © 2014, American Leather Chemists Association. (3) Photograph of water- repellent leather. 3.7. Self-cleaning leather modern leather products, especially for military shoes and uphol- stery crust leather. Leather products inevitably get stained during daily wear and Due to the low surface tension of organosilicon compounds, use. It is inconvenient to wash them, and so self-cleaning per- they are commonly used as waterproofing agents, smoothing formance of leather has become an important factor that needs agents, and softening agents for leather. Presently, traditional to be considered. Intelligent bionic surfaces have been tried in leather manufacturing generally uses organosilicon compounds as the leather industry, which involve imparting a high roughness leather finishing agents, fatliquors, and retanning agents to factor to leather by compounding leather with nano-solid par- improve the hydrophobicity of leather. Feng et al. [93] reported the ticles. This further improves the hydrophobic and oleophobic polymerization and deposition of vinyltriethoxysilane on the sur- properties, due to which leather does not get wet and remains face of upholstery crust leather by using low-pressure cold plasma non-oily with self-cleaning property. Nano-TiO2 particles provide technology, which improved the hydrophobicity of the leather photo-induced hydrophilicity and photocatalytic properties [85], surface (Fig. 10). It did not affect the appearance and sanitary per- photodegrade organic contaminants, and can be used to prepare formance of leather, which was difficult to obtain. In order to obtain self-cleaning films or coatings [86e88]. C. Gaidau, A et al. [89] leather coating with high hydrophobicity and good stability, Huang reported the synthesis of AgeNeTiO2 co-doped nanomaterials by et al. [94] combined the three-dimensional rough structure of the electrodeposition of Ag on NeTiO2 NPs, which improved the skin itself, firstly through in-situ hydrolysis of butyl titanate to photocatalysis, hydrophilicity, and antibacterial property of the generate TiO2 to enhance the roughness of the leather, and then use leather surface. Importantly, the leather surfaces treated with polydimethylsiloxane with low surface energy, high strength and AgeNeTiO2 NPs showed advanced self-cleaning properties, good softness to deposit nano-TiO2 leather was wrapped and when exposed to ultraviolet/visible light (Fig. 9), through the modified to prepare leather with a static contact angle of 164.6. hydrophilic mechanism to decompose organic soil. The modifi- cation of TiO2 with dopant ions renders it sensitive to visible 3.8.2. Water-, oil-, and soil-repellent leather light and the highly active free radicals generated on the surface Besides leather with outstanding water-repellency, there also under the influence of ultraviolet/visible light irradiation exists multi-functional leather with combined water-, oil-, and soil- participate in the oxidation reaction. This promotes the repellency, which is termed “tri-repellent” leather. The common destruction of organic pollutants and deactivates microbes [90], way to obtain “tri-repellent” leather is to add finishing agents, thus providing better antimicrobial resistance. Moreover, Fe and which also have the property of “tri-substrate-repellency”, to N co-doped TiO2, used in the preparation of FeeNeTiO2 nano- leather [95]. materials, not only endow leather with self-cleaning properties, but also enhance the hydrophobicity of the leather surface [91]. 4. Conclusion and outlook Furthermore, silica-doped TiO2 NPs also have obvious advantages of thermal resistance and catalytic performance in visible light Leather, the primary product of rawhide, has for centuries been for finished leather with self-clearing properties [92]. used for several purposes. This review briefly introduces the multi- hierarchical structure and properties of leather and summarizes 3.8. Other functional leathers and analyzes the existing functional leathers. The focus was on EW- absorbing leather, infrared-absorbing leather, X-ray shielding 3.8.1. Waterproof leather leather, conductive leather, flame-retardant leather, antibacterial Waterproof leather refers to the leather surface and fibers that leather, self-cleaning leather, and conventional functional leathers, are not wetted by water and whose water contact angle is greater such as waterproof leather and water-, oil-, and soil-repellent than 90 . Waterproofing is one of the essential requirements of leather. 163
  12. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 The reason why natural leather can be used to prepare various [6] J. Kanagaraj, T. Senthilvelan, R.C. Panda, S. Kavitha, Eco-friendly waste man- agement strategies for greener environment towards sustainable develop- functional materials is due to its specific structural features, which ment in leather industry: a comprehensive review, J. Clean. Prod. 89 (2015) are as follows: (1) Multi-layer braided structure and porous prop- 1e17, https://doi.org/10.1016/j.jclepro.2014.11.013. erties, which can be readily combined with functional materials; [7] J. Wegene, P. Thanikaivelan, Synergy of organic nanoclay and inorganic (2) Presence of multiple active groups such as amino and carboxyl phosphates for fire retardant leather applications, J. Am. Leather Chem. Assoc. 113 (11) (2018) 371e379. groups, which can be chemically modified to stabilize functional [8] L. Hiujian, Y. Jinwei, X. Ling, The synthesis and application of a high perfor- materials; (3) It has the advantages in terms of lightweight, soft- mance amino resin nanocomposite as a leather flame retardant, J. Soc. Leather ness, tailorability, and good wearability. Technol. Chem. 96 (1) (2012) 5e10. [9] Y. Liutao, L. Lixin, C. Wuyong, L. Lin, C. Feng, Thermal degradation kinetics and Therefore, by combining natural leather with other polymers flame retardancy of hide treated with montmorillonite-amino resin nano- (including synthetic polymers), leather with basic functions can be composite, J. Soc. Leather Technol. Chem. 94 (1) (2010) 9e14. transformed to multifunctional materials. Natural leather, with more [10] B. Zou, Y. Chen, Y. Liu, R. Xie, Q. Du, T. Zhang, Y. Shen, B. Zheng, S. Li, J. Wu, Repurposed leather with sensing capabilities for multifunctional electronic diverse functions, will be developed further in the future, which will skin, Adv. Sci, 6 (3) (2019) 1801283, https://doi.org/10.1002/advs.201801283. play an important role in more number of fields. Generally speaking, [11] L. Chirila, M. Stanca, C. Gaidau, D.M. Ra dulescu, M. Stroe, D.E. Ra dulescu, at present, research on special functional leather, such as EW shielded M. Baibarac, C. Alexe, Properties of textile and leather materials treated with new hybrid SiO2/TiO2/poly(2,2’-bithiophene) nanocomposites, INDUSTRIA leather, infrared camouflage leather, X-ray shielding leather and TEXTILA 70 (3) (2019) 236e241, https://doi.org/10.35530/IT.070.03.1634 (3). conductive leather is still not sufficiently mature and has still not [12] C. Liu, X. Wang, X. Huang, X. Liao, B. Shi, Absorption and reflection contri- reached the level of industrialization. Researchers are still making butions to the high performance of electromagnetic waves shielding materials fabricated by compositing leather matrix with metal nanoparticles, ACS Appl. efforts to add further value to leather, which is expected to serve the Mater. Inter. 10 (16) (2018) 14036e14044, https://doi.org/10.1021/ human society in a more comprehensive way. acsami.8b01562. Future development of functional leathers can be pursued in the [13] X. Wang, Y. Tang, Y. Wang, L. Ke, X. Ye, X. Huang, B. Shi, Leather enabled following ways: multifunctional thermal camouflage armor, Chem. Eng. Sci. 196 (2019) 64e71, https://doi.org/10.1016/j.ces.2018.12.005. (1) Development of economical, efficient, and safe functional [14] Q. Li, Y. Wang, X. Xiao, R. Zhong, J. Liao, J. Guo, X. Liao, B. Shi, Research on X-ray materials. (2) After specific functionalization of leather, the basic shielding performance of wearable Bi/Ce-natural leather composite materials, performances such as breathability and comfort should be retained. J. Hazard Mater. (2020) 122943, https://doi.org/10.1016/j.jhazmat.2020.122943. [15] A.M. Ferreira, P. Gentile, V. Chiono, G. Ciardelli, Collagen for bone tissue (3) The bonding between the functional materials and leather fibers regeneration, Acta Biomater. 8 (9) (2012) 3191e3200, https://doi.org/ must be increased. 10.1016/j.actbio.2012.06.014. As a novel advanced functional bio-based material, functional [16] K. Goerttler, W. Friedemann, Strukturelle Ver€ anderungen der Rückenhaut haarloser hr/hr-M€ ause w€ ahrend des Lebens, Arch. Klin. Exp. Dermatol. 237 (2) leather, is bound to promote the continuous development of special (1970) 635e651, https://doi.org/10.1007/BF00518396. functional materials and processing technologies. [17] X. Liu, C. Zheng, X. Luo, X. Wang, H. Jiang, Recent advances of collagen-based biomaterials: multi-hierarchical structure, modification and biomedical ap- plications, Mater. Sci. Eng. C 99 (2019) 1509e1522, https://doi.org/10.1016/ Author contributions j.msec.2019.02.070. [18] J.A. Petruska, A.J. Hodge, A Subunit model for the tropocollagen macromole- Conceptualization, X.L.; Investigation, Y.W., M.Z. and O.Y.; Wri- cule, Proc. Natl. Acad. Sci. U.S.A. 51 (1964) 871e876, https://doi.org/10.1073/ pnas.51.5.871. tingdoriginal draft preparation, Y.W. and M.Z.; Supervision, X.L., [19] T. Liu, L. Shi, Z. Gu, W. Dan, N. Dan, A novel combined polyphenol-aldehyde X.W. and H.J.; Funding acquisition, X.L. All authors have given crosslinking of collagen filmdapplications in biomedical materials, Int. J. Biol. approval to the final version of the manuscript. Macromol. 101 (2017) 889e895, https://doi.org/10.1016/j.ijbiomac.2017.03.166. [20] Z. Ganim, H.S. Chung, A.W. Smith, L.P. Deflores, K.C. Jones, A. Tokmakoff, Amide I two-dimensional infrared spectroscopy of proteins, Cheminform 41 Declaration of competing interest (3) (2008) 432e441, https://doi.org/10.1021/ar700188n. [21] L. Bozec, G. van der Heijden, M. Horton, Collagen fibrils: nanoscale ropes, Biophys. J. 92 (1) (2007) 70e75, https://doi.org/10.1529/biophysj.106.085704. The authors declare that they have no known competing [22] N. Perini, F. Mercuri, M.C. Thaller, S. Orlanducci, D. Castiello, V. Talarico, financial interests or personal relationships that could have L. Migliore, The stain of the original salt: red heats on chrome tanned leathers appeared to influence the work reported in this paper. and purple spots on ancient parchments are two sides of the same ecological coin, Front. Microbiol. 10 (2019), https://doi.org/10.3389/fmicb.2019.02459. [23] Y. Chen, H.B. Zhang, Y. Yang, M. Wang, A. Cao, Z.Z. Yu, High-performance Acknowledgements epoxy nanocomposites reinforced with three-dimensional carbon nanotube sponge for electromagnetic interference shielding, Adv. Funct. Mater. 26 (3) (2016) 447e455, https://doi.org/10.1002/adfm.201503782. We sincerely acknowledge the funding and generous support [24] D.X. Yan, H. Pang, B. Li, R. Vajtai, L. Xu, P.G. Ren, J.H. Wang, Z.M. Li, Structured from the National Key R&D Program of China (Grant No. reduced graphene oxide/polymer composites for ultra-efficient electromag- 2017YFB0308502), National Natural Science Foundation of China netic interference shielding, Adv. Funct. Mater. 25 (4) (2015) 559e566, https://doi.org/10.1002/adfm.201403809. (Grant Nos. 21808133 and 21804084), Scientific Research Founda- [25] Z. Zeng, H. Jin, M. Chen, W. Li, L. Zhou, Z. Zhang, Lightweight and anisotropic tion for Young Scholars (Grant No. 2017BT-32), and Xian yang Sci- porous MWCNT/WPU composites for ultrahigh performance electromagnetic ence and Technology Project (Grant No. 2018k02-28). interference shielding, Adv. Funct. Mater. 26 (2) (2016) 303e310, https:// doi.org/10.1002/adfm.201503579. [26] D. Wanasinghe, F. Aslani, A review on recent advancement of electromagnetic References interference shielding novel metallic materials and processes, Compos. B Eng. (2019) 107207, https://doi.org/10.1016/j.compositesb.2019.107207. [1] Covington, D. Anthony, Modern tanning chemistry, Chem. Soc. Rev. 26 (1997) [27] M. Cao, Y. Cai, P. He, J. Shu, W. Cao, J. Yuan, 2D MXenes: electromagnetic property 111, https://doi.org/10.1039/CS9972600111. for microwave absorption and electromagnetic interference shielding, Chem. [2] L. Falc~ ao, M.E.M. Araújo, Vegetable tannins used in the manufacture of historic Eng. J. 359 (2019) 1265e1302, https://doi.org/10.1016/j.cej.2018.11.051. leathers, Molecules 23 (5) (2018) 1081, https://doi.org/10.3390/molecules [28] M.H. Al-Saleh, W.H. Saadeh, U. Sundararaj, EMI shielding effectiveness of 23051081. carbon based nanostructured polymeric materials: a comparative study, [3] J.D. Wegene, P. Thanikaivelan, Conducting leathers for smart product appli- Carbon 60 (2013) 146e156, https://doi.org/10.1016/j.carbon.2013.04.008. cations, Ind. Eng. Chem. Res. 53 (47) (2014) 18209e18215, https://doi.org/ [29] H.G. Wei, H. Wang, A. Li, D.P. Cui, Z.N. Zhao, L.Q. Chu, X. Wei, L. Wang, D. Pan, 10.1021/ie503956p. J.C. Fan, Multifunctions of polymer nanocomposites: environmental remedi- [4] N. Ariram, B. Madhan, Development of bio-acceptable leather using ation, electromagnetic interference shielding, and sensing applications, bagasse, J. Clean. Prod. 250 (2020) 119441, https://doi.org/10.1016/j.jcle- ChemNanoMat 6 (2) (2020), https://doi.org/10.1002/cnma.201900588. pro.2019.119441. [30] Y. Zhang, T. Pan, Z. Yang, Flexible polyethylene terephthalate/polyaniline [5] J. Hu, W. Deng, Application of supercritical carbon dioxide for leather pro- composite paper with bending durability and effective electromagnetic cessing, J. Clean. Prod. 113 (2016) 931e946, https://doi.org/10.1016/j.jclepro. shielding performance, Chem. Eng. J. 389 (2020) 124433, https://doi.org/ 2015.10.104. 10.1016/j.cej.2020.124433. 164
  13. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 [31] C. Liang, H. Qiu, P. Song, X. Shi, J. Kong, J. Gu, Ultra-light MXene aerogel/wood- performance and low secondary radiation, ACS Appl. Mater. Inter. 12 (48) derived porous carbon composites with wall-like “mortar/brick” structures (2020) 54117e54126, https://doi.org/10.1021/acsami.0c17008. for electromagnetic interference shielding, Sci. Bull. 65 (8) (2020) 616e622, [56] J.D. Wegene, P. Thanikaivelan, K. Krishnaraj, K. Phebe, B. Chandrasekaran, https://doi.org/10.1016/j.scib.2020.02.009. A Novel Bi-functional Leather for Smart Product Applications and a Process for [32] P. Hu, J. Lyu, C. Fu, W. Gong, J. Liao, W. Lu, Y. Chen, X. Zhang, Multifunctional the Preparation There of, Indian Patent Application 1269Del2014, 2014. aramid nanofiber/carbon nanotube hybrid aerogel films, ACS Nano 14 (1) [57] G. Leto, D.J. Wager, Material for Use with a Capacitive Touch Screen, (2020) 688e697, https://doi.org/10.1021/acsnano.9b07459. US2012128995, 2012. [33] S. Mondal, S. Ganguly, P. Das, D. Khastgir, N.C. Das, Low percolation threshold [58] W. Jima Demisie, T. Palanisamy, K. Kaliappa, P. Kavati, C. Bangaru, Concurrent and electromagnetic shielding effectiveness of nano-structured carbon based genesis of color and electrical conductivity in leathers through in-situ poly- ethylene methyl acrylate nanocomposites, Compos. Part B-Eng. 119 (2017) merization of aniline for smart product applications, Polym. Adv. Technol. 26 41e56, https://doi.org/10.1016/j.compositesb.2017.03.022. (5) (2015) 521e527, https://doi.org/10.1002/pat.3483. [34] Z. Liang, Z. Zhao, M. Pu, J. Luo, X. Xie, Y. Wang, Y. Guo, X. Ma, X. Luo, Metallic [59] K.H. Hong, Preparation of conductive leather gloves for operating capacitive nanomesh for high-performance transparent electromagnetic shielding, Opt. touch screen displays, Fashion Textile Res. J. 14 (6) (2012) 1018e1023. Mater. Express 10 (3) (2020) 796e806, https://doi.org/10.1016/j.carbon. [60] E. Gasana, P. Westbroek, J. Hakuzimana, K. De Clerck, G. Priniotakis, P. Kiekens, 2015.10.004. D. Tseles, Electroconductive textile structures through electroless deposition [35] X. Zhang, X. Wang, Z. Lei, L. Wang, M. Tian, S. Zhu, H. Xiao, X. Tang, L. Qu, of polypyrrole and copper at polyaramide surfaces, Surf. Coating. Technol. 201 Flexible MXene-decorated fabric with interwoven conductive networks for (2006) 3547e3551, https://doi.org/10.1016/j.surfcoat.2006.08.128. integrated Joule heating, electromagnetic interference shielding, and strain [61] A. Malinauskas, Chemical deposition of conducting polymers, Polymer 42 (9) sensing performances, ACS Appl. Mater. Inter. 12 (12) (2020) 14459e14467, (2001) 3957e3972, https://doi.org/10.1016/S0032-3861(00)00800-4. https://doi.org/10.1021/acsami.0c01182. [62] Y. Khan, A.E. Ostfeld, C.M. Lochner, A. Pierre, A.C. Arias, Monitoring of vital [36] X. Wang, X. Huang, Z. Chen, X. Liao, C. Liu, B. Shi, Ferromagnetic hierarchical signs with flexible and wearable medical devices, Adv. Mater. 28 (22) (2016) carbon nanofiber bundles derived from natural collagen fibers: truly light- 4373e4395, https://doi.org/10.1002/adma.201504366. weight and high-performance microwave absorption materials, J. Mater. [63] T.Q. Trung, N.E. Lee, Flexible and stretchable physical sensor integrated plat- Chem. C. 3 (39) (2015) 10146e10153, https://doi.org/10.1039/c5tc02689j. forms for wearable human-activity monitoringand personal healthcare, Adv. [37] X. Wang, X. Liao, W. Zhang, B. Shi, Bio-inspired fabrication of hierarchical Mater. 28 (22) (2016) 4338e4372, https://doi.org/10.1002/adma.201504244. NieFeeP coated skin collagen fibers for high-performance microwave ab- [64] Z. Zou, C. Zhu, Y. Li, X. Lei, W. Zhang, J. Xiao, Rehealable, fully recyclable, and sorption, Phys. Chem. Chem. Phys. 17 (3) (2015) 2113e2120, https://doi.org/ malleable electronic skin enabled by dynamic covalent thermoset nano- 10.1039/c4cp03909b. composite, Abstr. Pap. Am. Chem. Soc. 256 (365) (2018). [38] C. Liu, X. Huang, J. Zhou, Z. Chen, X. Liao, X. Wang, B. Shi, Lightweight and [65] J. Kim, M. Lee, H.J. Shim, R. Ghaffari, H.R. Cho, D. Son, Y.H. Jung, M. Soh, C. Choi, high-performance electromagnetic radiation shielding composites based on a S. Jung, Stretchable silicon nanoribbon electronics for skin prosthesis, Nat. surface coating of Cu@ Ag nanoflakes on a leather matrix, J. Mater. Chem. C. 4 Commun. 5 (2014) 1e11, https://doi.org/10.1038/ncomms6747. (5) (2016) 914e920, https://doi.org/10.1039/c5tc02591e. [66] A. Chortos, J. Liu, Z. Bao, Pursuing prosthetic electronic skin, Nat. Mater. 15 (9) [39] B. Brodsky, A.V. Persikov, Molecular structure of the collagen triple helix, Adv. (2016) 937e950, https://doi.org/10.1038/nmat4671. Protein Chem. 70 (2005) 301e339, https://doi.org/10.1016/S0065-3233(05) [67] Q. Hua, J. Sun, H. Liu, R. Bao, R. Yu, J. Zhai, C. Pan, Z.L. Wang, Skin-inspired highly 70009-7. stretchable and conformable matrix networks for multifunctional sensing, Nat. [40] G.N. Ramachandran, Structure of collagen, Nature 174 (4423) (1954) Commun. 9 (2018) 1e11, https://doi.org/10.1038/s41467-017-02685-9. 269e270, https://doi.org/10.1038/174269c0. [68] C. Pang, G. Lee, T. Kim, S.M. Kim, H.N. Kim, S. Ahn, K. Suh, A flexible and highly [41] U. Hansen, P. Bruckner, Macromolecular specificity of collagen fibrillogenesis: sensitive strain-gauge sensor using reversible interlocking of nanofibres, Nat. fibrils of collagens I and XI contain a heterotypic alloyed core and a collagen I Mater. 11 (9) (2012) 795e801, https://doi.org/10.1038/NMAT3380. sheath, J. Biol. Chem. 278 (39) (2003) 37352e37359, https://doi.org/10.1046/ [69] C. Wang, K. Xia, H. Wang, X. Liang, Z. Yin, Y. Zhang, Advanced carbon for j.1365-2141.2000.02204.x. flexible and wearable electronics, Adv. Mater. 31 (9) (2019) 1801072, https:// [42] A. Rogalski, Infrared detectors: status and trends, Prog. Quant. Electron. 27 doi.org/10.1002/adma.201801072. (2003) 59e210, https://doi.org/10.1016/S0079-6727(02)00024-1. [70] R. Xie, S. Hou, Y. Chen, K. Zhang, B. Zou, Y. Liu, J. Liang, S. Guo, H. Li, B. Zheng, [43] W. Hu, Q. Li, X. Chen, W. Lu, Recent progress on advanced infrared photo- Leather-based strain sensor with hierarchical structure for motion moni- detectors, Acta Phys. Sin.-Ch. Ed. 68 (12) (2019) 120701, https://doi.org/ toring, Adv. Mater. Technol. 4 (10) (2019) 1900442, https://doi.org/10.1002/ 10.7498/aps.68.20190281. admt.201900442. [44] S. Hong, S. Shin, R. Chen, An adaptive and wearable thermal camouflage de- [71] X. Wang, O. Yue, X. Liu, M. Hou, M. Zheng, A novel bio-inspired multi-func- vice, Adv. Funct. Mater. 30 (11) (2020) 1909788, https://doi.org/10.1002/ tional collagen aggregate based flexible sensor with multi-layer and internal adfm.201909788. 3D network structure, Chem. Eng. J. (2020), https://doi.org/10.1016/ [45] T. Han, X. Bai, J.T. Thong, B. Li, C.W. Qiu, Full control and manipulation of heat j.cej.2019.123672. signatures: cloaking, camouflage and thermal metamaterials, Adv. Mater. 26 [72] H. Liao, X. Guo, P. Wan, G. Yu, Conductive MXene nanocomposite organo- (11) (2014) 1731e1734, https://doi.org/10.1002/adma.201304448. hydrogel for flexible, healable, low-temperature tolerant strain sensors, Adv. [46] H. Chu, Z. Zhang, Y. Liu, J. Leng, Silver particles modified carbon nanotube Funct. Mater. 29 (39) (2019), https://doi.org/10.1002/adfm.201904507. paper/glassfiber reinforced polymer composite material for high temperature [73] H. Li, J. Zhang, J. Chen, Z. Luo, J. Zhang, Y. Alhandarish, Q. Liu, W. Tang, L. Wang, infrared stealth camouflage, Carbon 98 (2016) 557e566, https://doi.org/ A supersensitive, multidimensional flexible strain gauge sensor based on Ag/ 10.1016/j.carbon.2015.11.036. PDMS for human activities monitoring, Sci. Rep.-UK 10 (1) (2020) 4639, [47] X. Liu, Y. Lai, J. Huang, S.S. Al-Deyab, K. Zhang, Hierarchical SiO2@ Bi2O3 core/ https://doi.org/10.1038/s41598-020-61658-z. shell electrospun fibers for infrared stealth camouflage, J. Mater. Chem. C. 3 (2) [74] Q. Li, H. Liu, S. Zhang, D. Zhang, X. Liu, Y. He, L. Mi, J. Zhang, C. Liu, C. Shen, (2015) 345e351, https://doi.org/10.1039/c4tc01873g. Superhydrophobic electrically conductive paper for ultrasensitive strain sensor [48] S. Hong, Y. Gu, J.K. Seo, J. Wang, P. Liu, Y.S. Meng, S. Xu, R. Chen, Wearable with excellent anticorrosion and self-cleaning property, ACS Appl. Mater. Inter. thermoelectrics for personalized thermoregulation, Sci. Adv. 5 (5) (2019), 11 (24) (2019) 21904e21914, https://doi.org/10.1021/acsami.9b03421. https://doi.org/10.1126/sciadv.aaw0536. [75] Y. Wang, M. Chao, P. Wan, L. Zhang, A wearable breathable pressure sensor [49] R. Xu, X. Xia, W. Wang, D. Yu, Infrared camouflage fabric prepared by paraffin from metal-organic framework derived nanocomposites for highly sensitive phase change microcapsule with good thermal insulting properties, Colloids broad-range healthcare monitoring, Nano Energy 70 (2020), https://doi.org/ Surf. A: Physicochem. Eng. Aspects 591 (2020) 124519, https://doi.org/ 10.1016/j.nanoen.2020.104560. 10.1016/j.colsurfa.2020.124519. [76] B. Duan, Q. Wang, X. Wang, Y. Li, M. Zhang, S. Diao, Flame retardance of [50] M.L. Monje, H. Toda, T.D. Palmer, Inflammatory blockade restores adult hip- leather with flame retardant added in retanning process, Results Phys. 15 pocampal neurogenesis, Science 302 (2003) 1760e1765, https://doi.org/ (2019), https://doi.org/10.1016/j.rinp.2019.102717. 10.1126/science.1088417. [77] Y. Fu, Y. Teng, G. Yu, C. Yin, Synthesis and structure properties of flame [51] S. Mizumatsu, M.L. Monje, D.R. Morhardt, R. Rola, T.D. Palmer, J.R. Fike, retardant and cationic dyeable polyamide 6 modified with 5-sulfoisophthalic Extreme sensitivity of adult neurogenesis to low doses of X-irradiation, acid sodium and melamine cyanurate, Fiber. Polym. 19 (7) (2018) 1363e1372, Cancer Res. 63 (14) (2003) 4021e4027. https://doi.org/10.1007/s12221-018-7656-7. [52] H. Lusic, M.W. Grinstaff, X-ray-computed tomography contrast agents, Chem. [78] L. Yang, Y. Liu, C. Ma, Y. Wu, W. Liu, C. Zhang, F. Wang, L. Li, Kinetics of non- Rev. 113 (3) (2013) 1641e1666, https://doi.org/10.1021/cr200358s. isothermal decomposition and flame retardancy of goatskin fiber treated with [53] Y. Wang, R. Zhong, Q. Li, J. Liao, N. Liu, N.S. Joshi, B. Shi, X. Liao, J. Guo, melamine-based flame retardant, Fiber. Polym. 17 (7) (2016) 1018e1024, Lightweight and wearable X-ray shielding material with biological struc- https://doi.org/10.1007/s12221-016-5808-1. ture for low secondary radiation and metabolic saving performance, Adv. [79] X. Yue, C. Li, Y. Ni, Y. Xu, J. Wang, Flame retardant nanocomposites based on Mater. Technol. 5 (7) (2020) 2000240, https://doi.org/10.1002/admt. 2D layered nanomaterials: a review, J. Mater. Sci. 54 (20) (2019) 1e36, https:// 202000240. doi.org/10.1007/s10853-019-03841-w. [54] Y. Wang, P. Ding, H. Xu, Q. Li, J. Guo, X. Liao, B. Shi, Advanced X-ray shielding [80] M. Lewin, Some comments on the modes of action of nanocomposites in the materials enabled by the coordination of well-dispersed high atomic number flame retardancy of polymers, Fire Mater. 27 (2003) 1e7, https://doi.org/ elements in natural leather, ACS Appl. Mater. Inter. 12 (17) (2020) 10.1002/fam.813. 19916e19926, https://doi.org/10.1021/acsami.0c01663. [81] G. Sanchez-Olivares, A. Sanchez-Solis, F. Calderas, L. Medina-Torres, [55] Q. Li, R. Zhong, X. Xiao, J. Liao, X. Liao, B. Shi, Lightweight and flexible Bi@ Bi-La O. Manero, A. Di Blasio, J. Alongi, Sodium montmorillonite effect on the natural leather composites with superb X-ray radiation shielding morphology, thermal, flame retardant and mechanical properties of semi- 165
  14. Y. Wang, M. Zheng, X. Liu et al. Journal of Science: Advanced Materials and Devices 6 (2021) 153e166 finished leather, Appl. Clay Sci. 102 (2014) 254e260, https://doi.org/10.1016/ [89] C. Gaidau, A. Petica, M. Ignat, O. Iordache, L. Ditu, M. Ionescu, Enhanced j.clay.2014.10.007. photocatalysts based on Ag-TiO2 and Ag-N-TiO2 nanoparticles for multifunc- [82] Y. Bao, C. Feng, C. Wang, J. Ma, C. Tian, Hygienic, antibacterial, UV-shielding tional leather surface coating, Open Chem. 14 (1) (2016) 383e392, https:// performance of polyacrylate/ZnO composite coatings on a leather matrix, doi.org/10.1515/chem-2016-0040. Colloids Surf. A: Physicochem. Eng. Aspects 518 (2017) 232e240, https:// [90] S. Rehman, R. Ullah, A.M. Butt, N.D. Gohar, ChemInform abstract: strategies of doi.org/10.1016/j.colsurfa.2017.01.033. making TiO2 and ZnO visible light active, Cheminform 170 (2e3) (2009) [83] M. Pollini, F. Paladini, A. Licciulli, A. Maffezzoli, A. Sannino, L. Nicolais, Antibacterial 560e569, https://doi.org/10.1016/j.jhazmat.2009.05.064. natural leather for application in the public transport system, J. Coating Technol. [91] A. Petica, C. Gaidau, M. Ignat, C. Sendrea, L. Anicai, Doped TiO2 nano- Res. 10 (2) (2013) 239e245, https://doi.org/10.1007/s11998-012-9439-1. photocatalysts for leather surface finishing with self-cleaning properties, [84] J. Xiang, L. Ma, H. Su, J. Xiong, K. Li, Q. Xia, G. Liu, Layer-by-layer assembly of J. Coating Technol. Res. 12 (6) (2015) 1153e1163, https://doi.org/10.1007/ antibacterial composite coating for leather with cross-link enhanced dura- s11998-015-9711-2. bility against laundry and abrasion, Appl. Surf. Sci. 458 (2018) 978e987, [92] C. Gaidau, A. Petica, M. Ignat, L.M. Popescu, R.M. Piticescu, I.A. Tudor, https://doi.org/10.1016/j.apsusc.2018.07.165. R.R. Piticescu, Preparation of silica doped titania nanoparticles with thermal [85] S. Banerjee, D.D. Dionysiou, S.C. Pillai, Self-cleaning applications of TiO2 by stability and photocatalytic properties and their application for leather surface photo-induced hydrophilicity and photocatalysis, Appl. Catal. B Environ. 176 functionalization, Arab. J. Chem. 10 (7) (2017) 985e1000, https://doi.org/ (2015) 396e428, https://doi.org/10.1016/j.apcatb.2015.03.058. 10.1016/j.arabjc.2016.09.002. [86] H. Peeters, M. Keulemans, G. Nuyts, F. Vanmeert, C. Li, M. Minjauw, [93] Y.E. Feng, X. Liao, Y.N. Wang, B. Shi, Improvement in leather surface hydro- C. Detavernier, S. Bals, S. Lenaerts, S.W. Verbruggen, Plasmonic gold-embedded phobicity through low-pressure cold plasma polymerization, J. Am. Leather TiO2 thin films as photocatalytic self-cleaning coatings, Appl. Catal. B Environ. Chem. Assoc. 109 (3) (2014) 89e95. 267 (2020) 118654, https://doi.org/10.1016/j.apcatb.2020.118654. [94] X. Huang, X. Kong, Y. Cui, X. Ye, X. Wang, B. Shi, Durable super- [87] C. Han, L. Zhao, M. Zhang, L. Pan, Z. Liu, Synthesis and self-cleaning property of hydrophobic materials enabled by abrasion-triggered roughness regener- TiO2 thin film doping with Fe3þ, Al3þ, Ce3þ ions, J. Nanosci. Nanotechnol. 20 ation, Chem. Eng. J. 336 (2018) 633e639, https://doi.org/10.1016/j.cej. (7) (2020) 4084e4091, https://doi.org/10.1166/jnn.2020.17691. 2017.12.036. [88] I. Ali, M. Suhail, Z.A. Alothman, A. Alwarthan, Recent advances in syntheses, [95] Z. Dongmei, L. Yan, S. Qianhong, W. Xinmin, Q. Shuanggui, S. Jiansong, Anti- properties and applications of TiO2 nanostructures, RSC Adv. 8 (53) (2018) bacterial water and oil repellent multifunctional finishing agent for fabric, 30125e30147, https://doi.org/10.1039/c8ra06517a. Rare Met. Mater. Eng. 41 (30) (2012) 655e658. 166
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