Durable flame retardant finishing of cotton fabrics with organosilicon functionalized cyclotriphosphazene

A multi-functional coating on cotton fabric to incorporate electro-conductive, anti-bacterial, and flame-retardant properties

Multi-functional textiles have become a growing trend among smart customers who dream of having multiple functionalities in a single product. Thus, this study aimed to develop a multi-functional textile from a common textile substrate like cotton equipped with electrically conductive, anti-bacterial, and flame-retardant properties. Herein, a bunch of compounds from various sources like petro-based poly-aniline (PANI), phosphoric acid (H3PO4), inorganic silver nanoparticles (Ag-NPs), and biomass-sourced fish scale protein (FSP) were used. The coating was prepared via in-situ polymerization of PANI with the cotton substrate, followed by the dipping in AGNPs solution, layer-by-layer deposition of FSP and sodium alginate, and finally, a dip-dry-cure technique after immersing the modified cotton substrate into the H3PO4 and citric acid solution. The key results indicated that the fabric treated with PANI/Ag-NPs/FSP/P-compound exhibited a balanced improvement in all three desired properties as the electrical resistance was reduced by 44.44 % while showing superior bacterial inhibition against gram-positive bacteria (S. aureus) and gram-negative bacteria (E. coli), and produced dense-black carbonaceous char residues, indicating its flame retardant properties as well. Thus, such amicable developments made the cotton textile substrate a multi-functional textile, which showed potential to be used in medical textiles, wearable electronics, fire-fighter suits, etc.

Cyclotriphosphazene: A Versatile Building Block for Diverse Functional Materials

Cyclotriphosphazene (CP) is a cyclic inorganic compound with the chemical formula N3P3. This unique molecule consists of a six-membered ring composed of alternating nitrogen and phosphorus atoms, each bonded to two chlorine atoms. CP exhibits remarkable versatility and significance in the realm of materials chemistry due to its easy functionalization via facile nucleophilic substitution reactions in mild conditions as well as intriguing properties of resultant final CP-based molecules or polymers. CP has been served as an important building block for numerous functional materials. This review provides a general and broad overview of the synthesis of CP-based small molecules through nucleophilic substitution of hexachlorocyclotriphosphazene (HCCP), and their applications, including flame retardants, liquid crystals (LC), chemosensors, electronics, biomedical materials, and lubricants, have been summarized and discussed. It would be expected that this review would offer a timely summary of various CP-based materials and hence give an insight into further exploration of CP-based molecules in the future.

Multi-functionalization of cotton fabrics with excellent flame retardant, antibacterial and superhydrophobic properties

Cotton fabric is widely used in many fields for its excellent comfortability, breathability and hygroscopicity. However, the development of multifunctional cotton fabrics to meet the requirements of different scenarios is a top priority. In this study, multifunctional coating was constructed through facile layer-by-layer assembly phytic acid and chitosan, and spraying divalent copper ion and polydimethylsiloxane (PDMS) on cotton fabrics, anticipating to endow them with flame retardancy, antibacterial and superhydrophobic properties simultaneously. The treated cotton fabric achieved a limiting oxygen index (LOI) value of 32 %, with the char length reducing to 10.7 cm revealing excellent flame retardancy. The water contact angle of multifunctional treated cotton fabric was above 150°, demonstrating it had superhydrophobicity. The antibacterial rates of multifunctional cotton fabrics against E. coli and S. aureus reached to higher than 99 %, indicating that the excellent antibacterial properties. Combined with the thermal stability of cotton fabrics and their char residues analysis, these results demonstrated that the multifunctional coating could act through intumescent flame retardant mechanism to flame retardant cotton fabrics. This research provides a facile way to prepare multifunctional cotton fabrics to broaden the application prospect.

Barrier Effects of Cellulosic Fibers with Hybrid Coating Based on Zirconium Metal-Organic Framework

Metal-organic frameworks (MOFs) have great potential for the development of fire barriers for flammable materials. Accordingly, zirconium-based metal-organic framework (Zr-MOF), branched polyethyleneimine (BPEI), and vinyltriethoxysilane (VTES) were deposited to produce composites assembled on cellulosic fibers to investigate their barrier effects. The structure, morphology, and thermal properties of the cellulosic fibers were characterized using FTIR spectroscopy, SEM, and TGA. Compared with the untreated cotton sample, the temperature of the maximum rate of weight loss (T_max) of C-Zr-MOF/BPEI/VTES increased from 479 to 523.3 °C and the maximum weight loss rate (R_max) at T_max decreased from 37.6 to 17.2 wt%/min. At 800 °C, the pristine cotton was burned out without residues whereas the residual char content of the C-Zr-MOF/BPEI/VTES sample was 7.2355 wt%. From the vertical burning tests, the results suggested that the C-Zr-MOF/BPEI/VTES sample had better barrier effects by reducing the flame-spread speed and generating more protective char layers.

High-Efficiency Flame Retardants of a P-N-Rich Polyphosphazene Elastomer Nanocoating on Cotton Fabric

Modification by intumescent flame retardants is an effective way to impart antiflame properties to fabric materials. Polyphosphazene elastomers contain all three elements required by intumescent flame retardants: an acid source, a gas source, and a carbon source, making them all-in-one integrated intumescent flame retardants. In this work, halogen-free poly(dimethoxy)phosphazene (PDMP) loaded with 29.0 wt % phosphorus and 13.1 wt % nitrogen is shown to be an ideal flame retardant for fabric materials. For the first time, transparent and elastic PDMP was applied as an intumescent flame retardant for cotton fabric. The PDMP-coated cotton shows remarkable high-efficiency flame-retardant properties: (1) a self-extinguishing property during the vertical flame test is obtained when the add-on level reaches 5.3 wt %, with a lower smoke release character; (2) the limiting oxygen index (LOI) values of coated cotton are improved with increasing add-on level, and the thickness of the coating is measured to be at the nanolevel, 2540 nm when 10.9 wt % PDMP is coated. The coated cotton shows enhanced carbonization ability at lower temperatures, which is the key to imparting flame-retardant properties to cotton, and the PDMP-coated cotton shows remarkably lower peak heat release rate and total heat release compared to the control cotton during combustion. The durability of modified cotton was tested after 50 laundering cycles, which showed that the coating maintains 80% of its initial mass, and the after-laundering sample preserves the characteristics of self-extinguishing and a high LOI. Thus, the PDMP nanocoating-modified flame-retardant cotton fabric is sufficiently durable for practical application.

Multifunctional Cotton Fabrics Obtained by Modification with Silanes Containing Esters of Phosphoric Acid as Substituents

The development of novel flame retardants for cotton textiles that form a stable layer on textile fiber is of high economical and practical relevance. A novel flame retardant fluorinated phosphoric acid esters modified silicone resins for cotton modification were synthesized. The investigated phosphoric acid esters based compounds were substituted by a fluorinated chain or ring, and alkoxysilyl groups. The presence of alkoxysilyl groups allowed the formation of bonds with cellulose, while derivatives of phosphoric esters reduced the flammability of fabrics. Additionally, the presence of fluoride in their structures affected the hydrophobic properties. Cotton fabrics were modified in a simple one-step process by dip-coating method. The flame retardant properties of modified textiles were examined by performing microcalorimetric analysis, thermogravimetry analysis, and measuring oxygen index. The hydrophobicity was evaluated by measuring the water contact angle. The modified fabrics were characterized by SEM-EDS (Scanning Electron Microscopy with Energy Dispersive Spectroscopy) analysis and surface morphology. As a result of the tests, multifunctional fabrics were obtained.

Flame-Retardant Textile-Based Triboelectric Nanogenerators for Fire Protection Applications

Textile-based triboelectric nanogenerators (T-TENGs), combining the functions of energy harvesting and self-powered sensing with advantages of breathability and flexibility, have received intensive attention, which is vital to the rapid advancements in smart textiles. However, there exists few reports of T-TENGs applied to fires under the intelligent era of high requirements for devices with versatility and multiscenario practicability. Here, in combination with flame-retardant conductive cotton fabric, polytetrafluoroethylene-coated cotton fabric, and a divider, a low-cost and environmentally friendly flame-retardant textile-based triboelectric nanogenerator (FT-TENG) is developed, which is endowed with excellent fire resistance and outstanding energy harvesting capabilities. The cotton fabrics treated with a layer-by-layer self-assembly method show great self-extinguishing performance. Besides, the maximum peak power density of the FT-TENG can reach 343.19 mW/m² under the tapping frequency of 3 Hz. Furthermore, the FT-TENG still keeps 49.2% of the initial electrical output even after being burned at 17 different positions; 34.48% of the electrical output is also retained when the FT-TENG is exposed to 220 °C. Moreover, the FT-TENGs are successfully applied as energy harvesters for firefighters and self-powered sensors for forest self-rescue and fire alarm systems. This work may provide a promising potential for multifunctional smart textiles in energy harvesting, self-powered sensing, and life or property security.

Hybrid Porous Microparticles Based on a Single Organosilica Cyclophosphazene Precursor

Porous organosilica microparticles consisting of silane-derived cyclophosphazene bridges were synthesized by a surfactant-mediated sol-gel process. Starting from the substitution of hexachlorocyclotriphosphazene with allylamine, two different precursors were obtained by anchoring three or six alkoxysilane units, via a thiol-ene photoaddition reaction. In both cases, spherical, microparticles (size average of ca. 1000 nm) with large pores were obtained, confirmed by both, scanning and transmission electron microscopy. Particles synthesized using the partially functionalized precursor containing free vinyl groups were further functionalized with a thiol-containing molecule. While most other reported mesoporous organosilica particles are essentially hybrids with tetraethyl orthosilicate (TEOS), a unique feature of these particles is that structural control is achieved by exclusively using organosilane precursors. This allows an increase in the proportion of the co-components and could springboard these novel phosphorus-containing organosilica microparticles for different areas of technology.

Synthesis of multielement phosphazene derivative and the study on flame-retardant properties of epoxy resin

Herein, we have successfully synthesized phosphorus/nitrogen/silicon tri-elements compound phosphazene derivative hexa-[4-( N-(3-(triethoxysilyl)propyl)acetamide)phenoxy]cyclotriphosphazene (HNTPC) from hexachlorotriphosphazenitrile, methyl 4-hydroxybenzoate, and 3-triethoxysilylpropylamine, and it was used as an additive flame retardant in epoxy resin (EP). Then, the thermal stability and flame retardancy of the composite (HNTPC/EP) were tested. Thermogravimetric analysis showed that the presence of HNTPC made EP matrix decompose at a relatively low temperature, thus promoted the formation of a stable coke layer and protected the matrix from fire. Therefore, the amount of carbon residue was markedly increased at 800°C, indicating an outstanding condensed phase flame-retardant effect. Furthermore, various combustion test data manifested that the addition of HNTPC could significantly improve the flame-retardant performance of EP. In addition, the sample could pass the vertical burning tests (UL-94) V-1 grade when the addition amount was 10% and the limiting oxygen index value was 32.6%, the peak heat release rate and total heat release rate decreased by 40.0% and 21.5%, respectively. Besides, the results of scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy also showed that HNTPC can promote the formation of carbon layer and improved the flame-retardant property of EP. Finally, the condensed phase and gas phase synergistic flame-retardant mechanism of HNTPC was proposed.

Surface Functionalization of Cotton and PC Fabrics Using SiO2 and ZnO Nanoparticles for Durable Flame Retardant Properties

In recent years, the use of functional textiles has attained attention due to their advantageous health and safety issues. Therefore, this study investigated the flame retardancy on cotton (COT) and polyester-cotton (PC) fabrics treated with different concentrations of silica and zinc nanoparticles through a sol-gel finishing technique. FTIR, SEM, and TGA were conducted for the characterization of coated fabric samples. The FTIR and SEM of Pristine and Treated Cotton and PC fabrics illustrated that the SiO2 (silica dioxide) and ZnO (Zinc oxide) nanoparticles were homogeneously attached to the fiber surface, which contributed to the enhancement of the thermal stability. The starting thermal degradation improved from 320 to 350 °C and maximum degradation was observed from 400 to 428 °C for the COT-2 cotton substrate. However, the initial thermal degradation improved from 310 to 319 °C and the highest degradation from 500 to 524 °C for the PC substrate PC-2. The outcomes revealed that the silica has a greater influence on the thermal properties of COT and PC fabric samples. Additionally, the tensile strength and flexural rigidity of the treated samples were improved with an insignificant decrease in air permeability.

Preparation of a Novel Flame Retardant Formulation for Cotton Fabric

A novel halogen-free flame-retardant formulation was prepared and coated onto cotton fabrics. The structure of phosphorus compounds in the system was characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance spectroscopy (¹H-NMR). Results from the ATR-FTIR spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) analyses presented that the flame retardant was coated successfully onto a cotton surface. We investigated the thermal stability and fire-retardant behaviors of cotton fabrics using thermal gravimetric analysis (TGA) and the vertical flame test. We also discuss the mechanism of flame retardance of coated cotton fabrics.

Synthesis of a Novel Linear α, ω-Di (Chloro Phosphoramide) Polydimethylsiloxane and Its Applications in Improving Flame-Retardant and Water-Repellent Properties of Cotton Fabrics

A novel linear α, ω-di (chloro phosphoramide)-terminated polydimethylsiloxane (CPN-PDMS) was successfully synthesized and utilized as a formaldehyde-free water-repellent and flame-retardant for cotton fabrics. The flame retardancy of treated cotton fabrics was estimated by limiting oxygen index (LOI) test, vertical flammability test, and cone calorimetry test. The cotton fabrics treated with 350 g/L CPN-PDMS obtained excellent flame retardancy with an LOI value of 30.6% and the char length was only 4.3 cm. Combustion residues were studied using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analysis. Results show that CPN-PDMS can effectively enhance water repellency and fire resistance of cotton fabrics. Furthermore, the breaking strength test and the whiteness test strongly prove that the tensile strength and whiteness of the treated cotton fabrics were slightly lower than that of the pure cotton fabrics. The wash stability test showed that after 30 laundering cycles, the treated cotton fabrics still had an LOI value of 28.5% and a water-repellent effect of grade 80, indicating that CPN-PDMS was an excellent washing durability additive. In summary, these property enhancements of treated cotton fabrics were attributed to the synergistic effect of silicon-phosphorus-nitrogen elements in CPN-PDMS.

A Green Water-Soluble Cyclophosphazene as a Flame Retardant Finish for Textiles

Poly- and cyclophosphazenes are excellent flame retardants but currently, are not used as textile finishing agents because water-soluble and permanent washing systems are missing. Here, we demonstrate for the first time, the successful usage of a water-soluble cyclotriphosphazene derivative for textile finishing for cotton, different cotton/polyester, and cotton/polyamide blend fabrics. A durable finish was achieved using a photoinduced grafting reaction. The flame retardant properties of the various fabrics were improved with a higher limiting oxygen index, a reduced heat release rate, and an exhibition of intumescent. Furthermore, the finished textiles passed several standardized flammability tests.

A facile coating with water-repellent and flame-retardant properties on cotton fabric

We herein present a facile method to fabricate functional cotton fabric (CF) with superhydrophobic surface and excellent fire-resistance property by coating with chitosan (CS)/phytic acid (PA) layer and hydrophobic silicon dioxide nanoparticles.

Preparation and performance testing of superhydrophobic flame retardant cotton fabric

A superhydrophobic flame retardant coating was fabricated using a simple method of depositing a DAP coating and a H-ZrO₂@PDMS coating on the surface of a cotton fabric. Thermal stability tests and vertical burning tests demonstrate the excellent flame retardancy of the coating.

Development and Evaluation of a Water-Based Flame Retardant Spray Coating for Cotton Fabrics

In this Research Article, we report on the development of water-based flame retardant coating based on phospho-nitrogen combination for cotton fabrics. A one-step spray-on process was employed to coat the fabrics by taking advantage of the spontaneous reaction between para-phenylenediamine (PDA) and tetrakis(hydroxymethyl)phosphonium chloride (THPC) resulting in an instantaneous precipitation of poly[1,4-diaminophenylene-tris(dimethyl hydroxymethyl)phosphine] (PApP) on the fabric surface. The effectiveness of PApP in improving the flame retardant properties like ignition resistance and lateral flame spread were evaluated in accordance with ASTM D6413 and BS EN ISO 15025 flammability tests. Despite the early (thermal) decomposition onset for coated fabrics under both oxidative and pyrolytic conditions, remarkably, self-extinguishing behavior (<3 s) without any lateral flame spread was observed. Possible reaction scheme was also proposed to correlate flame retardant mechanism of the coated fabrics with the observations. Additional analysis via pyrolysis combustion flow calorimetry and vertical flame testing before and after washing showed that flame retardant efficiency did decrease with washing, but the overall performance was still promising.

Preparation of a reactive flame retardant and its finishing on cotton fabrics based on click chemistry

The non-halogenated organophosphorus flame retardant dimethyl-[1,3,5-(3,5-triacryloylhexahydro)triazinyl]-3-oxopropylphosphonate (DHTP) was synthesized and immobilized on cotton fabrics for a flame retardant finishing using click chemistry.

Recent Advances for Flame Retardancy of Textiles Based on Phosphorus Chemistry

This paper aims at updating the progress on the phosphorus-based flame retardants specifically designed and developed for fibers and fabrics (particularly referring to cotton, polyester and their blends) over the last five years. Indeed, as clearly depicted by Horrocks in a recent review, the world of flame retardants for textiles is still experiencing some changes that are focused on topics like the improvement of its effectiveness and the replacement of toxic chemical products with counterparts that have low environmental impact and, hence, are more sustainable. In this context, phosphorus-based compounds play a key role and may lead, possibly in combination with silicon- or nitrogen-containing structures, to the design of new, efficient flame retardants for fibers and fabrics. Therefore, this review thoroughly describes the advances and the potentialities offered by the phosphorus-based products recently developed at a lab-scale, highlighting the current limitations, open challenges and some perspectives toward their possible exploitation at a larger scale.