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The facile development of a sustainable and durable flame-retardant approach for protein silk is of interest. Inspired by silk tin-weighting technology, this study developed a novel and sustainable in-situ deposition strategy based on biomass phytic acid to impart durable flame-retardant performance to silk fabrics. The chemical structure of insoluble chelating precipitation, and the surface morphology, thermal stability, combustion behavior, flame-retardant capacity, laundering resistance, and flame-retardant mode of action of the tin-weighting silk samples, were explored. The Sn-, P-, Si-containing insoluble chelating precipitation formed within the fiber interior and combined with silk fibers through electrostatic attraction and metal salt chelation. As a result, the tin-weighting silk displayed excellent self-extinguishing capacity, with the damaged length reduced to 9.2 cm and the LOI increased to 31.6 %; it also achieved self-extinguishing after 30 washing cycles, demonstrating high flame-retardant efficacy and laundering resistance. Moreover, the tin-weighting silk also showed the obvious suppression in smoke and heat generation by 55.6 % and 35.7 %, respectively. The synergistic charring action of phosphate groups, tin metal salts, and silicates was beneficial for enhancing the fire safety of silk. The tin-weighting treatment also displayed a minor impact on mechanical performance of silk fabrics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

For protein fibers, polycarboxylic acids represent a green strategy to enhance durability without using formaldehyde. This study evaluated the physical and flame retardant properties of silk fabrics treated with three formaldehyde-free crosslinkers: citric acid (CA), 1,2,3,4-butanetetracarboxylic acid (BTCA), and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA). Results showed that these acids bond with silk protein through esterification and amidation, improving washing durability. Particularly, PBTCA integrates phosphorus into silk, boosting flame retardancy. While BTCA led to the highest weight gain and improved wrinkle recovery, it negatively impacted the tensile strength and softness of silk fabrics. Conversely, PBTCA adeptly balanced enhanced wrinkle resistance with minimal effects on tensile strength and softness, and least affected the silk fabrics' whiteness, thus preserving its aesthetic appeal. All crosslinkers improved flame retardancy, but PBTCA displayed superior performance, achieving a limiting oxygen index of 32.4 % at an 80 g/L concentration. In vertical burning tests, PBTCA treated silk fabrics showed reductions in damage length and demonstrated self-extinguishing properties, qualifying them for a higher flame retardant grade. Phosphorus in PBTCA promotes char formation during combustion, essential for effective flame retardation and smoke reduction. This research highlights the exceptional potential of silk treated with PBTCA, showcasing its suitability for demanding applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Nowadays, high value-added and multifunctional textiles have attracted widespread attention due to the changing demands of modern life. This study focused on the fabrication of silk with photochromism, flame retardancy, UV resistance and durability using riboflavin sodium phosphate (RSP) and various metal ions (Fe 2+ , Fe 3+ , Al 3+ , and Ti 4+ ). Attractively, the photochromic performance was one of the most distinctive features of the modified silk, and the yellow silk fabric turned into fluorescent green under UV lamp. After a detailed comparison, it was determined that RSP/Fe 3+ hybrid system was most effective in improving anti-UV performance of the silk with a high UPF of 25.8, achieving a "Good" level of UV protection. Specifically, it achieved a B 1 fire protection with a low damaged-length of 9.4 cm and a high LOI of 28.3 %. Additionally, the modified silk showed the lowest smoke density, reducing by approximately 84.1 % versus that of pristine silk. Moreover, the modified silk was able to meet the B 1 classification and the "Good" UV protection requirements even after 75 washing cycles, making it more durable than most functional textiles reported. The further analysis indicated that RSP and metal ions can synergistically enhance the condensed-phase action, thereby improving the fire resistance of silk., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Inorganic magnesium hydroxide nanoparticles (Mg(OH) 2 NPs) offer a promising halogen-/phosphorus-free flame-retardant solution for silk. However, achieving effective and durable flame retardancy remains a challenge. In this study, silane-modified Mg(OH) 2 NPs were prepared using the double drop-reverse precipitation method with the silane coupling agent 3-aminopropyltriethoxysilane as a surface modifier. The chemical bonding between silane-modified Mg(OH) 2 NPs and silk fabric was beneficial for improving the stabilization and durability of the functional particles on the silk surface. The surface morphology and structure of the silane-modified Mg(OH) 2 NPs, as well as the smoke and heat generation performance, flame retardancy, washing durability, and flame-retardant mechanism of the coated silk fabrics were investigated. The coated silk fabric exhibited high flame-retardant efficiency and significantly reduced smoke and heat generation, indicating a lower fire hazard. Additionally, the coated silk fabric displayed self-extinguishing behavior even after 15 robust washings, demonstrating high washing durability. The coated silk exhibited fibrous and weave structures after combustion, indicating a strong charring ability. Overall, this study presents a promising approach for the development of flame-retardant silk fabrics with excellent washing durability using inorganic Mg(OH) 2 NPs. [Display omitted] • Silane-modified magnesium hydroxide nanoparticles (Mg(OH) 2 NPs) is applied as inorganic flame-retardant coating for silk. • Silane-modified Mg(OH) 2 NPs coating endows silk textile with effective and durable flame retardancy. • Silane-modified Mg(OH) 2 NPs coating significantly suppresses the smoke and heat generation of silk textile. • Silane-modified Mg(OH) 2 NPs coating serves as a sustainable and promising technique to minimize fire hazards of silk textile. [ABSTRACT FROM AUTHOR]

The development of sustainable, efficient and durable flame-retardant (FR) coating for silk fabric using plant-derived phytic acid is of great interest. This work synthesized a novel and reactive intumescent FR agent namely glycidyl phytate isocyanurate (GPIC) through ring-opening addition reaction using phytic acid and 1,3,5-triglycidyl isocyanurate. Then, the durable FR coated silk fabric was developed with GPIC through the surface coating route. The chemical structure of GPIC, and its cross-linking mechanism with silk, the smoke and heat generation performance, flame retardancy and washing durability of coated silk were studied. The coated silk fabric with a weight gain of 13.6 % could self-extinguish and possessed a high limiting oxygen index (LOI) value of 32.5 %. GPIC coating would be covalently cross-linked onto silk fabric and the coated silk fabric could withstand 30 washing cycles, displaying high washing durability. GPIC coating also significantly suppressed the smoke and heat generation of silk fabric during combustion. The coated silk fabrics had high thermal stability and left significant inflated char residues after the burning tests. The intumescent FR performance of GPIC was beneficial from the synergistic effect of phytate and triazine-trione groups. [Display omitted] • Sustainable and reactive glycidyl phytate isocyanurate (GPIC) intumescent flame-retardant is synthesized. • GPIC coating is grafted on silk surface through covalent reaction. • GPIC coating has high flame retardancy and durability on silk textile. • GPIC coating functions by taking advantage of synergistic action of phytate and triazine-trione groups. • GPIC coating offers an eco-friendly and durable flame-retardant approach for silk in practical applications. [ABSTRACT FROM AUTHOR]

In this work, a novel phosphorus-rich hybrid organic-inorganic silica coating for improving the flame retardancy of silk fabric was prepared using naturally occurring phytic acid as phosphorus precursor and catalyst for the hydrolysis of tetraethoxysilane. In addition, three silane coupling agents, namely 3-aminopropyldimethoxymethylsilane, 3-chloropropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane, were added in the hybrid sol as cross-linkers with the aim of developing hydrophobic coatings and improving the washing durability of the treated silk fabric. The condensation degree of the hybrid sol was characterized by solid-state 29 Si nuclear magnetic resonance spectroscopy. The flammability and thermal degradation properties of the treated silk fabrics were determined in terms of limiting oxygen index, vertical burning, pyrolysis combustion flow calorimetry and thermogravimetric analyses. The surface morphology and hydrophobicity of the treated silk fabrics were evaluated by scanning electron microscopy, atomic force microscopy and water contact angle tests. The flammability tests revealed that the silicon sol could endow silk fabric with excellent flame retardancy when doped with phytic acid, and the treated silk fabrics self-extinguished immediately when the ignition source was removed. The silk fabrics treated with the modified hybrid sols exhibited hydrophobic surface and also better durability to washing. [ABSTRACT FROM AUTHOR]

This research work reported a novel approach to develop flame retardant silk fabric using naturally occurring phytic acid (PA) rich in phosphorus and TiO 2 nanoparticles through a pad-dry-cure technique. A polycarboxylic acid [1,2,3,4–butanetetracarboxylic acid (BTCA)] was employed to stabilize and improve the adhesion of TiO 2 on silk surface. The flame retardancy of the treated silk fabric was determined in terms of limiting oxygen index, vertical burning, and pyrolysis combustion flow calorimetry, and the durability of flame retardancy to washing was discussed. PA and TiO 2 were found to have a joint flame retardant effect. The combination of PA, TiO 2 and BTCA was able to endow silk fabric with excellent flame retardancy, and the good flame retardant ability was kept even after 25 times of washing. The reasons for the good washing durability of the treated silk fabric were discussed. Finally, a significant condensed-phase flame retardant mechanism of the silk fabric treated with the PA/TiO 2 /BTCA system was revealed by the analyses of thermogravimetry and pyrolysis combustion flow calorimetry. [ABSTRACT FROM AUTHOR]

This paper reports a simple one-step process for the in-situ synthesis and deposition of silver nanoparticles (AgNPs) on silk fabric by employing caffeic acid as an eco-friendly reductant. The formation of AgNPs was confirmed by visible colour changes and UV–visible spectra. The surface plasmon resonance band of AgNPs was observed at λ max ∼414–420 nm indicating spherical or roughly spherical AgNPs, which was further confirmed by TEM and SEM measurements. The surface of AgNPs treated silk showed roughness due to the deposition of AgNPs and the uniform distribution of roughly spherical AgNPs on silk surface was observed in SEM images. EDS analysis also confirmed the presence of silver in treated silk. An increase in the amount of caffeic acid and silver nitrate resulted in more silver being deposited on silk fabric. The caffeic acid assisted in-situ generation of AgNPs imparted golden yellow colour and good multi-functional properties to silk fabric. The treated fabrics showed excellent fastness towards washing, rubbing and light. The antibacterial effect was highly durable as more than 90% bacterial reduction was observed even after 10 washing cycles. [ABSTRACT FROM AUTHOR]

• Sustainable and reactive pentaerythritol phytate ethylenediaminetetraacetic acid ester (PPEDTE) intumescent flame-retardant is synthesized. • PPEDTE coating is grafted on silk surface through covalent reaction. • PPEDTE coating has high flame retardancy and durability on silk textile. • PPEDTE coating offers an eco-friendly and durable flame-retardant approach for silk in practical applications. The exploitation of plant-derived phytic acid as effective and durable flame retardant (FR) for textiles is of great significance for developing novel and ecological functional textile products. In the present study, a reactive and phytate-based FR namely pentaerythritol phytate ethylenediaminetetraacetic ester (PPEDTE) prepared by the esterification of phytic acid, pentaerythritol and ethylenediaminetetraacetic acid was investigated as intumescent FR agent for silk fabric. The chemical structure of PPEDTE and its potential grafting mechanism on silk were studied. The thermal stability, heat and smoke suppression property, flame retardancy and washing resistance on silk fabric were studied. The deposition and covalently cross-linked PPEDTE on silk fabric enabled it to self-extinguish in vertical burning test. The coated silk fabric with an add-on of higher than 10.7% could withstand 15 washing cycles, displaying good washing durability. The intumescent FR coating remarkably decreased the release of heat and smoke of silk during burning. The coated silk had high thermal stability and left significant combustion residues after the burning tests. These results demonstrate that the synthesized PPEDTE warrant potential as efficient and reactive intumescent FR approach for silk. [Display omitted] [ABSTRACT FROM AUTHOR]

• Highly sticky functional coating is in-situ fabricated on silk surface. • The functional coating is grafted on silk surface through covalent reaction. • The functional coating has high flame retardancy and thermal stability on silk textile. • The functional coating pyrolyzes through intumescent charring mechanism. • The functional coating offers an effective and durable strategy to minimize fire hazards of silk textile. The novel strategies for fabricating durable flame retardant (FR) silk fabric with biomass phytic acid (PA) is of interest. In this study, a highly sticky coating was in-situ developed on the surface of silk fabric by adsorption of PA, 1,4-Phthalaldehyde and followed by adsorption of 3-aminopropyltriethoxysilane (KH550). The Schiff base reaction would occur between 1,4-Phthalaldehyde and silk fiber/KH550, and thus the sticky coating could be firmly grafted on silk surface. The thermal degradation, smoke and heat emission properties, flame retardancy, and washing durability of coated silk were explored. The FR coating displayed high functional efficiency and thermal stability by taking advantage of synergistic effect with phosphate groups and silica networks. The modified silk fabrics also possessed lower fire hazards as suggested by significantly reduced smoke and heat generation. The coated silk fabrics self-extinguished and obtained a char length of 13.5 cm after 20 washing cycles. The improved washing resistance should be ascribed to the covalently grafted sticky coating on silk surface. In general, this work reports a novel and feasible strategy to develop durable silk textile using bioderived PA. [Display omitted] [ABSTRACT FROM AUTHOR]

² Reactive synergistic P/Si/N-containing hybrid silica sol system is prepared. ² Hybrid silica coating has high flame retardancy and washing durability on silk textile. ² Hybrid silica coating acts as the intumescent charring flame-retardant action. ² Hybrid silica coating offers an effective and durable strategy to minimize the fire hazards of silk textile. The fabrication of phosphorus-doped sol-gel coatings for durable flame retardant (FR) modification of textiles are of interest. This study facilely synthesized a novel phosphorus-doped silica sol system using 3-aminopropyltriethoxysilane, glutaraldehyde, diethyl phosphite by simultaneous Kabachnik-Fields and sol-gel reactions. The morphology and chemical structures of hybrid silica particles were studied by TEM, FT-IR and NMR. Then, the hybrid silica sol was applied as durable FR coating to reduce the flammability of silk. The FR property and washing durability, smoke and heat generation capacity, thermal stability, and FR mechanism of coated silk fabrics were explored. The hybrid silica coating displayed good FR performance because of the synergistic action among Si, P and N. The coated fabrics self-extinguished after 25 launderings and had a high LOI value of 28.0% thanks to the covalent grafting of hybrid silica coating on silk fabrics. The explorations on silk residues confirmed the intumescent FR mechanism of coated silk. The hybrid silica coating is promising to functional as feasible and durable FR strategy for silk fabric. [Display omitted] [ABSTRACT FROM AUTHOR]

• Reactive synergistic P/N/S-containing flame retardant GASDP is prepared. • GASDP has high flame retardant ability and washing durability on silk textile. • GASDP has good smoke suppression ability on silk textile. • GASDP functions through both gas phase and condensed phase action. • GASDP offers an effective and durable strategy to minimize the fire hazards of silk textile. Improving flame retardancy of silk fabric will expand its potential application fields. Herein, a novel P/N/S-containing flame retardant (FR) named glutaraldehyde ammonium sulfamate diethyl phosphate salt (GASDP) was prepared by one-pot reaction among glutaraldehyde, ammonium sulfamate and diethyl phosphite. We further explored its potential applications in durable FR modification of silk fabric through textile exhaustion approach. The grafting mechanism, thermal stability, flame retardancy and washing durability, and FR mechanism of the coated silk fabrics were studied. GASDP coating showed high FR functional efficiency due to the synergism among P, N and S. The coated silk fabric covalently grafted by GASDP had a high LOI of about 30.0%; it still reached B 1 classification after 25 washing cycles. GASDP coating exerted good flame retardancy to silk fabric through the intumescent FR mechanism. GASDP coating displays great potential to functional as efficient and durable approach to improve flame retardancy of silk fabric. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Phytic acid and tartaric acid are derived from resourceful plants or crops. • Tartaric acid phytate ester (TAPE) is a reactive flame retardant. • TAPE could react with silk fiber to form ester and amide covalent bonds. • TAPE shows high flame retardant efficiency and durability on silk fabric. • TAPE offers a sustainable and durable strategy to minimize the fire hazards of silk textiles. The development of effective and reactive flame retardant (FR) using natural products is of interest for sustainable FR textiles. This study focused on the synthesis of a reactive phosphorus-based FR agent (tartaric acid phytate ester (TAPE)) using plant-derived phytic acid and tartaric acid. We further studied its potential applications in durable FR modification of silk fabric. The chemical structure of TAPE and its potential bonding mechanism with silk fibers were explored. The thermal stability, smoke and heat generation performance, and flame retardancy of the modified silk fabrics were investigated. Char residue analyses were also performed to study the FR mechanism of TAPE on silk fabric. The results revealed that TAPE imparted higher thermal and flame resistance to silk and remarkably inhibited the smoke and heat generation of silk through a condensed charring mechanism. The introduction of TAPE to silk was driven by ester and amide covalent bonds and electrostatic attraction. This leads to good washing durability of the modified silk as reflected by the self-extinguishing action of modified silk after 20 washing cycles. In general, this research provides a novel strategy to develop a reactive FR agent as well as sustainable and durable FR functional silk textiles using bio-based plant extracts. [ABSTRACT FROM AUTHOR]

Nano-magnesium hydroxide (nano-Mg(OH) 2) serves as a promising flame retardant (FR) filler for plastics, but it remains a challenge to endow textiles with effective and durable FR ability. In the present work, Mg(OH) 2 nanoparticles with an average diameter of 68 nm were prepared via the double precipitation method with Tween 80 as surface modifier. Then, nano-Mg(OH) 2 was used to prepare the functional silk fabric with enhanced FR ability and smoke suppression to reduce the fire risk of silk through surface coating technique using polycarboxylic acid as cross-linker. The morphology and structure of nano-Mg(OH) 2 were studied, and the smoke/heat emission ability, FR ability and durability, and functional mechanism of the coated silk were also investigated. The nano-Mg(OH) 2 coating imparted high FR property to silk and greatly decreased the smoke/heat generation ability of silk. The coated silk fabric also displayed self-extinguishing action after 15 washing cycles, demonstrating good washing durability for the coated silk fabric. The coated silk obtained dense and continuous char residue, exhibiting excellent charring ability. This study proves that nano-Mg(OH) 2 could serve as an effective and sustainable FR agent for enhancing the fire safety of silk fabric. [Display omitted] • Nano-Mg(OH) 2 coating imparts effective flame retardancy and smoke suppression to silk textile. • Nano-Mg(OH) 2 coating has good washing durability on silk textile. • Nano-Mg(OH) 2 coating acts as char-former in condensed phase. • Nano-Mg(OH) 2 coating offers a effective and sustainable strategy to fabricate functional silk textile. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flame retardant silk textile was fabricated through Kabachnik-Fields reaction. • The modified silk textile had durable flame retardant effect. • The flame retarding activity served as intumscent charring mechanism. • This study offers an effective and durable strategy to reduce fire risks of silk textile. This study facilely developed the durable flame retardant (FR) silk fabric by bonding phosphonate groups to silk fiber through Pudovik addition of diethyl phosphite onto Schiff base aldehyde-amine intermediate, namely Kabachnik-Fields reaction. The cross-linking mechanism between FR agent and silk fiber, the thermal resistance, FR ability and durability, and FR mechanism of the modified silk were studied. The modified silk had increased thermal resistance. The modified silk fabric with diethyl phosphite over 13.8 g/L had the self-extinguishing ability and obtained the char length of lower than 11.0 cm and LOI value of higher than 27.4 %, suggesting high FR ability of the modified silk. The modified silk also reached self-extinction after 15 robust launderings, which should be attributed to the covalent cross-linking of phosphonate groups onto silk fiber. The char residue analyses suggested a condensed charring FR mechanism for the modified silk. The Pudovik addition of diethyl phosphite onto silk macromolecular participated Schiff base intermediate shows great possibility to act as effective and durable FR strategy for silk textile. [ABSTRACT FROM AUTHOR]

In this study, a reactive boron-containing flame retardant (FR) namely glycerol borate citric acid ester (GBCAE) was synthesized using boric acid, glycerol and citric acid, and was applied to improve the flame retardancy of silk fabric. The chemical structure of GBCAE and its potential cross-linking reactions with silk fiber were characterized. The thermal stability, smoke and heat suppression capacity and FR ability of the treated silk were evaluated. The treated silk fabrics with a weight gain of higher than 7.3% had self-extinguishing ability. The FR treatment endowed high thermal stability and excellent flame retardancy to silk, and suppressed the smoke and heat release of silk by nearly 50%. The treated silk could still self-extinguish after 5 washing cycles and showed good washing durability, which is attributed to the covalent cross-linking action between GBCAE and silk fiber. The char residue analyses on morphology and functional groups indicated the intumescent FR mechanism for the treated silk. The prepared GBCAE has great potential to serve as suitable alternative to toxic halogen-based agents for improving the flame retardancy of silk textiles Unlabelled Image • Reactive, halogen-free and boron-based flame retardant GBCAE is prepared. • GBCAE imparts semi-durable flame retardancy to silk textile. • GBCAE has excellent smoke and heat suppression abilities on silk textile. • GBCAE acts as an intumescent charring flame retardant system. [ABSTRACT FROM AUTHOR]

This study aimed at the preparation of caramel product by heating glucose at alkaline condition and its application to develop flame retardant silk fabric. Caramel product was employed to silk through a facile exhaustion approach, and the adsorption property, color depth, flame retardancy and washing durability of caramel on silk fabric were investigated. The adsorption of caramel product on silk at acidic condition imparted brown color and good flame retardancy to silk fabric with self-extinguish ability. The modified silk fabric could still pass the vertical flammability measurement after 15 washing cycles, showing good durability to washing. The bubbling property of caramel during heating is responsible for the enhanced flame retardancy of silk as the formed intumescent char layer could protect silk substrates, revealing a condensed charring mechanism for the modified silk fabric. The caramel product modification exerted little adverse impacts on the handle and tensile strength of silk. The flame retardant modification of silk using eco-friendly and sustainable caramel product is a cleaner production approach compared to the synthetically engineered chemicals. Image 1 • Caramel product has been approved and safely used in foods and beverages. • Caramel product is prepared by heating glucose in alkaline condition. • Caramel product is a green, eco-friendly and sustainable flame retardant. • Caramel imparts semi-durable flame retardancy to silk via facile adsorption technique. • Caramel product acts as an intumscent charring flame retardant system. [ABSTRACT FROM AUTHOR]

Natural bioactive compounds have received increasing attention in the functional modification of textiles. In this work, tannic acid was used to impart antibacterial and antioxidant functions to silk using an adsorption technique, and the adsorption properties of tannic acid on silk were studied. The adsorption quantity of tannic acid on silk increased with decreasing pH in the range of 3–7. The rates of the uptake of tannic acid by silk were well correlated to the pseudo-second-order kinetic model, and the calculated activation energy of adsorption was 93.49 kJ/mol. The equilibrium adsorption isotherms followed the Langmuir model. The adsorption rate and isotherm studies demonstrated that the chemical adsorption of tannic acid on silk occurred through the ion-ion interaction between tannic acid and silk. Tannic acid displayed good building-up properties on silk. The silk fabric treated with 0.5% tannic acid (relative to fabric weight) exhibited excellent and durable antibacterial properties. Moreover, the silk fabrics treated with 2% and 5% tannic acid had good and durable antioxidant properties. The treatment by tannic acid had less impact on the whiteness of the silk fabric. In summary, tannic acid can be used as a functional agent for preparing healthy and hygienic silk materials. [ABSTRACT FROM AUTHOR]

Abstract Because of the urgent needs for eco-friendly textiles and environmental protection, the development and application of sustainable flame retardant (FR) agents have become a research hotspot. In this work, naturally occurring and phosphorus-rich phytic acid (PA) was used to improve the FR ability of silk/wool blend using an adsorption technique, and comparative studies were conducted on the application conditions, FR effect, smoke suppression, heat release capability, catalytic char forming, and FR mechanism of PA and conventional FR agents (K 2 TiF 6 and K 2 ZrF 6). The application of PA at pH 1.3–2.0, moderate temperature, and proper concentration remarkably improved the FR ability of the blend as per the limiting oxygen index and vertical burning assessments. Although the PA treated blend was inferior to the K 2 TiF 6 treated blend in initial FR ability, it exhibited better FR effect after repeated washing. Among three FR agents used, PA had the best smoke suppression, lowest heat release capability, highest ability to inhibit the thermal oxidation of the degraded products of fibers, and best catalytic char forming effect. PA acted as an effective FR in the solid phase. However, the application of PA had a shortcoming of decreasing the whiteness of the blend. Graphical abstract Image 1 Highlights • Phytic acid was used as flame retardant for silk/wool blend. • Applications of phytic acid and conventional metal complexes were compared. • Phytic acid showed the best catalytic char forming effect. • Phytic acid exhibited the best smoke suppression. • Treated silk/wool blend exhibited the lowest heat release capability. [ABSTRACT FROM AUTHOR]

A rapid, green and simple procedure for the in-situ generation of AgNPs@silk as functional colorant is described herein. Silver (Ag + ) ions were first diffused into the silk fabric matrix by soaking into aqueous AgNO 3 solution, subsequently, alcoholic solution of ferulic acid, a natural polyphenol, was added as an eco-friendly reductant for the generation of AgNPs@silk. The formation of AgNPs was confirmed by visible color changes and UV–visible absorption spectra. The residual AgNPs solution was characterized via UV–visible spectroscopy, TEM and DLS. The UV–visible spectra and TEM analyses confirmed the formation of more or less spherical well-dispersed AgNPs. The AgNPs@silk was characterized by SEM, EDS, XRD, XPS and FTIR. The Ag content of AgNPs@silk was determined by nitric acid digestion followed by ICP-OES. The color, antibacterial and UV protection characteristics of AgNPs@silk were also evaluated. AgNPs@silk produced a beautiful color pallete ranging from light creamish brown to dark golden brown. The AgNPs treated silk exhibited outstanding antibacterial activity (>99% bacterial reduction) and excellent laundering durability, where it inhibited >94% of E. coli even after 10 washing cycles. Moreover, AgNPs@silk was highly effective blocking of UV radiation in both UVA and UVB regions, and thus offered excellent UV protection. [ABSTRACT FROM AUTHOR]

[Display omitted] • Squid ink (SI) can be obtained from waste ink glands. • Squid ink is rich in proteoglycan, melanin, and metal ions. • The treated silk exhibit superior flame retardancy, good UV protection and washing durability. • The proposed approach offers a sustainable and cleaner method for creating high value-added silk. Today, marine biomolecules have attracted great interest in the field of flame-retardant (FR) science due to their sustainability and charring properties. Squid ink is mixed bio-colloid rich in proteoglycans, melanin, and metal ions. Here, squid ink was applied to endow silk with outstanding FR performance and ultraviolet protection through surface coating. After coating with 40 g/L squid ink, silk displayed excellent ultraviolet shielding performance with a high UV protection factor (UPF) of 71.5, attributing to powerful ultraviolet absorption ability of melanin. Besides, the coated silk also exhibited outstanding FR performance, characterized by a shorter char length (7.1 cm) and a higher FR-Index (2.5). The heat release performance of the treated silk dramatically decreased, and the peak heat release rate (pHRR) and heat release capability (HRC) both decreased by 49.1 %. Moreover, a significant reduction in total smoke production (TSP ∼ 60 %) was also observed in cone calorimetry test. A reduction in these fire parameters indicated a great improvement in the fire safety of silk. Interestingly, due to the natural adhesiveness of the proteoglycan mixed colloid, the coated silk could withstand 10 washing cycles while maintaining FR properties. Subsequently, further analyses of the cone residues confirmed the formation of a compact and stable char layer. The squid ink coating exerted an intumescent FR action on silk. [ABSTRACT FROM AUTHOR]

The growing awareness of human health and environmental protection stimulates the development of more sustainable flame retardant (FR) approaches. In this study, polyaniline (PANI) with a nitrogen-containing aromatic structure was synthesized as a novel functional compound to improve the FR and UV protection performance of silk fabric. Biobased chitosan was applied to develop the PANI/chitosan coating to improve the binding capability and dispersion uniformity of PANI on the silk surface. The surface morphology, thermal resistance, heat generation capacity, flame retardancy and UV protection performance were explored. The PANI/chitosan coating with 3 wt% PANI endowed the silk fabric with effective flame retardancy. The coated silk fabric self-extinguished during vertical flammability test and possessed a decreased char length of 9.5 cm versus 30 cm of the pristine silk fabric; it could also withstand 20 launderings, showing good laundering resistance. The coated silk fabric displayed markedly decreased heat release behavior. A combined condensed phase and gas phase FR action was suggested for the PANI/chitosan coating on silk fabric. The coated silk fabric also exhibited excellent UV protection with the UPF of 50+ because of the UV-shielding of PANI. [Display omitted] • Polyaniline (PANI) is applied as halogen-/phosphorus-free flame-retardant for silk. • PANI/chitosan coating imparts effective flame-retardant and UV protection properties for silk textile. • PANI/chitosan coating works by the combined condensed and gas phase action. • PANI/chitosan coating serves as a sustainable and promising technique to minimize fire hazards of silk textile. [ABSTRACT FROM AUTHOR]

• Metal salts are proved to have enough flame retardant efficiency on silk textile. • Metal salts impart semi-durable flame retardancy to silk textile. • Metal salts have good smoke suppression ability on silk textile. • Metal salts act as the condensed charring flame retardant approach. • Metal salts offer an effective strategy to minimize the fire hazards of silk textile. In this study, flame retardant (FR) functional silk fabric was prepared by the facile adsorption of metal salts (ferrous, aluminum and titanium sulfate) at low concentration. This study tried to provide a good understanding on the FR ability and action of metal salts on silk fabric. The morphological structure and functional groups of silk fiber before and after treatment were studied. The thermal stability, smoke generation ability and FR ability of the treated silk were evaluated. The iron, aluminum and titanium salts endowed silk fabric with self-extinction effect at a concentration of 0.1, 0.5 and 1.0 g/L, respectively. The metal salts also showed good washing resistance on silk fabric; for example, the aluminum salt treated silk still reached self-extinction after 10 robust washings, which is attributed to the complexation capacity of silk macromolecule with metal ions. The thermal stability and char residues analyses suggested the condensed phase FR mechanism for the treated silk, and the good ability to promote char formation contributed to their FR functionality. This study suggests that certain metal salts are effective enough to serve as suitable alternative to toxic halogen-based chemicals for enhancing fire safety of silk textiles. Image, graphical abstract [ABSTRACT FROM AUTHOR]