H3PO3-protonated chitosan enabling flame-retardant and antibacterial PVA composite films with high strength and toughness through multiple H-bonds and interlocking interfaces
Xing Cao , Xinyu Tian , Yuanyuan Huang , Liping Zhang , Yanpeng Ni , Yu-Zhong Wang
Polyvinyl alcohol (PVA) boasts excellent film-forming ability, mechanical properties, and biodegradability, extensively applied in various industries such as textiles, packaging, electronics, and biomedical engineering [1-4]. However, the intrinsic structure of PVA renders it highly flammable and susceptible to bacterial growth, presenting significant fire safety and health [5-8]. Conventional flame retardants including magnesium hydroxide, ammonium polyphosphate, and melamine phosphonate, along with antibacterial agents such as zinc oxide and cuprous oxide, while effective, frequently compromise PVA's mechanical strength, toughness, and transparency. These detrimental effects stem primarily from dispersion and compatibility challenges within the PVA matrix [9,10]. This limitation significantly restricts the practical applications of PVA materials, particularly in PVA film products with extensive applications. Additionally, contemporary material development increasingly prioritizes environmental safety, sustainability, and high performance [11,12]. Therefore, the urgent need exists to engineer flame-retardant and antibacterial PVA systems that offer high efficiency, superior mechanical properties, transparency, environmental friendliness, and sustainability.
Inspired by mussels and spider silk, researchers have developed biomimetic materials with high strength and toughness using molecular-scale interactions [13-15]. By combining this design strategy with PVA's unique multi-hydrogen bonding properties, they have introduced various dynamic multi-hydrogen-bonding crosslinking agents such as inositol [16], melamine [17], graphene [18], and MXene [19] to successfully develop robust PVA composites. These composites exhibit superior strength and toughness due to the strong hydrogen bonding between the fillers and PVA matrix. Expanding on this construction strategy, incorporating small molecules with multiple hydrogen bond sites and flame-retardant elements, such as phosphorus-containing polyamines or alcohols, enables the development of PVA composites that possess flame retardancy, high strength, toughness, and transparency [20]. For instance, Song et al. [21] fabricated robust and transparent PVA films using a small-molecule polyamine with a cyclotriphosphazene structure (HCPA), achieving an LOI value of 25.6% at 10 wt% loading. However, while these methods provide new insights into designing high-performance flame-retardant PVA, they fail to address antibacterial challenges. Furthermore, given the significant dependence on fossil resources for the synthesis of these flame retardants, their long-term sustainability remains questionable.
Chitosan, a natural alkaline polysaccharide derived from chitin deacetylation, exhibits broad-spectrum antibacterial activity [22,23]. Its structure, rich in hydroxyl, amino, and amide groups, facilitates effective hydrogen bonding. Chitosan also serves as an ideal carbon source in flame retardant formulations due to its carbonization properties [24-27]. Nevertheless, the flame-retardant efficacy remains limited without synergistic combinations with other flame retardants or chemical modifications that introduce flame-retardant elements. Phosphorylated chitosan, a chitosan derivative bearing phosphate groups, can simultaneously function as an acid source, gas source, and carbon source, thereby conferring efficient flame retardancy. Li et al. [28] synthesized phosphorylated chitosan via the Mannich reaction and applied it as a flame-retardant coating on cotton fabrics. At a 7.5% mass fraction, this coating increased the LOI value to 25.7%. Based on the biomimetic construction strategy, incorporating phosphorylated chitosan derivatives into PVA is anticipated to simultaneously achieve flame retardancy, reinforcement, and toughening. However, the synthesis process of phosphorylated chitosan is complex, typically necessitating high temperatures, significant chemical reagents, and intricate purification. Therefore, developing a facile method to prepare PVA materials using chitosan that exhibit high performance, flame retardancy, antibacterial properties, and sustainability remains a significant challenge.
Herein, H3PO3-protonated chitosan derivative (PCS) was synthesized under mild conditions utilizing an atom-economical approach. Subsequently, the derivative was incorporated into PVA as a multi-hydrogen-bonding crosslinking agent and a “three-in-one” macromolecular flame retardant. The aim was to simultaneously enhance the mechanical strength, toughness, flame retardancy and antibacterial properties of PVA composite films. A comprehensive investigation was conducted on the hydrogen bonding interactions, microstructure, and the effects of PCS content on the mechanical properties, flame retardancy, and antibacterial performance of PVA-PCSx films. The mechanisms of flame retardancy and synchronous strengthening and toughening were also revealed.
PCS was synthesized via the protonation of chitosan's amino groups using equimolar amounts of phosphorous acid (Fig. 1a). This approach was characterized by simplicity, mild reaction conditions, and high atomic efficiency. The FT-IR spectrum (Fig. 1b) revealed new absorption bands at 2380 cm−1 (attributed to P-H stretching) and 1540 cm−1 (corresponding to -NH3+ bending). Furthermore, the chemical shifts and integrals of each peak in the 1H NMR spectrum (Fig. 1c) aligned with the expected values for the target compound. Additionally, the 31P NMR spectrum of PCS displayed a single peak. These results confirmed the successful synthesis of PCS. The findings further validated that upon blending PCS and PVA solutions, a uniform mixture could be obtained across a broad spectrum of their ratios. Following the drying process, this homogeneous mixture gave rise to highly transparent PVA-PCS composite films (Fig. 1d).
To investigate the robust intermolecular hydrogen bonding interactions between PVA and PCS, the shifts in the O—H stretching vibration peaks in composite films with different blending ratios were hereby analyzed. As shown in Fig. 1e, the incorporation of PCS into PVA resulted in a significant redshift phenomenon that intensified with increasing PCS content. Specifically, the O—H stretching vibration bands shifted from 3265 cm−1 in pure PVA to 3259 cm−1 for PVA-PCS8, 3243 cm−1 for PVA-PCS11, and 3236 cm−1 for PVA-PCS14. Evidently, this pronounced redshift indicated strong intermolecular hydrogen bonding interactions between PCS and PVA. This very conclusion was further supported by the dynamic rheological test results of the mixed PVA-PCS solution (Fig. S1a in Supporting information). The dynamic rheological curves revealed that, compared to pure PVA, the storage modulus (G') of the PVA-PCS solution experienced a substantial elevation. Moreover, the slope in the low-frequency region decreased, and a well-defined plateau region came into existence. This implied that strong hydrogen bonding interactions between PCS and PVA had established a robust physical cross-linking network within the system [31].
Due to the presence of strong intermolecular hydrogen bonding, the PCS and PVA polymer segments could diffuse bidirectionally, thereby achieving excellent dispersion and compatibility. SEM images (Fig. S1b in Supporting information) showed that PVA-PCSx films possessed a uniform and smooth surface similar to pure PVA films, with no visible agglomeration. Elemental mapping of phosphorus confirmed even distribution, indicating effective PCS dispersion (Fig. S1c in Supporting information). As shown in the TEM image (Fig. 1f), sub-micron-sized domains were uniformly dispersed within the continuous PVA matrix. Linear elemental scanning of TEM images showed enhanced concentrations of P and N elements in these domains compared to the surrounding PVA matrix. This confirmed their primary existence as PCS aggregates (Fig. 1f). In the AFM phase image (Fig. 1g), alternating bright and dark phase domains can indeed be observed, with the bright regions corresponding to relatively harder PCS phases. This confirms evident phase separation, with the PCS phase domain size reaching the sub-micron level, which is consistent with the TEM findings. Despite PCS forms aggregated microphase domains within the PVA matrix, these domains exhibited an irregular, divergent “dandelion-like” morphology. Notably, there was no tight aggregation within the PCS phase domains, and a distinct light-and-dark alternating structure remained visible. This phenomenon was mainly attributed to the mutual diffusion of PVA and PCS components via hydrogen bonding, which blurred the interface between the PVA and PCS phases and created a transition zone at the interfacial layer. Consequently, an interlocking micro-nano scale interface architecture resembling a “dandelion-like” pattern was formed between the PCS-rich and PVA-rich domains. As a result, the interfacial bonding strength between PVA and PCS was enhanced, which was evidently advantageous for achieving PVA-PCSx composite films featuring robust mechanical properties.
The glass transition temperature (Tg) was defined as the temperature at which amorphous molecular chains initiated segmental motion, and it was related to the intermolecular interactions within these chains. The strong hydrogen bonds between PVA and PCS significantly increased the density of dynamic physical cross-linking networks, thereby inhibiting PVA segment mobility and raising the Tg of PVA-PCSx composites. According to DSC analysis (Fig. 2a), the Tg of pristine PVA was 81.2 ℃, while the Tg values for PVA-PCS8, PVA-PCS11, and PVA-PCS14 increased to 87.0 ℃, 88.4 ℃, and 93.2 ℃, respectively.
Fig. 2b presents the stress-strain curve acquired from tensile testing. Due to the H-bonding cross-linking networks and excellent compatibility between PCS and PVA, along with a unique micro-nano interlocking interface, the overall mechanical performance of various PVA-PCSx composite films including tensile strength, elongation at break, fracture toughness, and Young's modulus, were significantly improved compared to pure PVA. Specifically, tensile strengths for PVA-PCS8, PVA-PCS11, and PVA-PCS14 increased to 94.7, 112.4, and 115.6 MPa, from 76.7 MPa for pure PVA. Concurrently, the Young's modulus also increased by over 60% (Table S1 in Supporting information). Toughness-related metrics, including elongation at break and fracture toughness, initially increased and subsequently decreased as the content of PCS increased. However, these values consistently remained higher than those of pure PVA (Figs. 2c and d). PVA-PCS8 showed the highest elongation at break (94.7%) and fracture toughness (81.6 MJ/m3), which were 23.5% and 107.6% higher than PVA, respectively. Even with a slight decline, PVA-PCS14 still exhibited an elongation at break of 71.2% and fracture toughness of 70.8 MJ/m3, representing increases of 10% and 80.2% over PVA.
The reinforcement and toughening mechanisms could be explained as follows: PCS molecular chains were more rigid than PVA, and both polymers interacted through multiple hydrogen bonds. This resulted in the formation of a dynamic physical cross-linking network at the molecular level and interlocking interface architecture at the micro-nano scale. Consequently, PCS acted as a reinforcing phase and physical cross-linking point, constraining the movement of the softer PVA molecular chains and establishing a strong multi-scale energy dissipation network within the PVA-PCSx composites. Through rapid breaking and reforming of dynamic hydrogen bonds, coupled with the interlocking interfaces, thin films could effectively disperse external forces during tensile deformation and thus mitigated stress concentration and crack propagation, thereby enhancing strength and toughness. With increasing PCS content, the hard phase region and hydrogen-bonded cross-linked density increased correspondingly. This enhanced the constraint on PVA segment movement, improving tensile strength and modulus. However, an excessively high cross-linking density could make the network overly rigid. This would impede the slipping of PVA molecular chains and their conformational changes. As a result, the energy dissipation capacity would be diminished, ultimately leading to a reduction in the material's toughness.
To investigate the influence of PCS on the thermal degradation and char formation of PVA-PCSx composite films, thermogravimetric analysis (TGA) was hereby conducted in a nitrogen atmosphere. The TGA and DTG curves are shown in Figs. 2e and f, with data detailed in Table S2 (Supporting information). All samples exhibited similar thermogravimetric trends, characterized by three typical stages. Stage one involved minor weight loss at low temperatures due to moisture evaporation. Stage two, presenting the most significant weight loss, resulted from thermal elimination of side groups in PVA, leading to main chain breakage, cyclization, and formation of unstable carbon residues. Stage three involved continuous pyrolysis of these residues. Due to the premature degradation of PCS, the initial decomposition temperature (T5%) and the second stage decomposition temperature of the PVA-PCSx composite films were advanced. Specifically, for pure PVA film, T5% occurred at 265 ℃ and Td1,max at 299 ℃. In contrast, for PVA-PCSx composites, T5% ranged from 226 ℃ to 239 ℃, and Td1,max from 269 ℃ to 285 ℃. The acidic byproducts during decomposition, such as phosphoric acid, promoted PVA dehydration and carbonization, leaving more condensed phase residues and reducing volatile gas formation. This significantly inhibited the thermal weight loss rate in the second stage. As a result, the char residue continued to decompose into stable residual char with increasing temperature. At 700 ℃, the residue mass (R700) of PVA-PCSx films was substantially higher than that of pure PVA. For example, PVA-PCS11 had a residue mass of 23.4%, approximately 10 times higher than PVA's 2.1%. TGA data obviously showed that PCS effectively catalyzed PVA to accelerate char formation, which was conducive to improving flame retardancy.
The flame retardancy of PVA-PCSx films was evaluated through LOI, UL-94 vertical burning, microcalorimetry, and cone calorimetry test. The results are presented in Fig. 3 and Table 1. As shown in Fig. 3a, pure PVA exhibited intense burning upon ignition, failing to self-extinguish until completely burned out, and caused serious dripping that ignited absorbent cotton. For the PVA-PCSx samples, as the PCS content increased, the composite films demonstrated progressively enhanced self-extinguishing and charring properties. While the PVA-PCS8 did not pass the UL-94 test, its flame spread rate decreased significantly. Meanwhile, no fire dripping was observed during combustion. When the PCS content was increased to 11 wt% and 14 wt%, both PVA-PCS11 and PVA-PCS14 composite films achieved self-extinguishing after first and second ignitions, respectively. Notably, both samples demonstrated significant charring tendencies post-ignition. Throughout the entire testing process, no dripping was observed, and the samples successfully achieved the UL-94 V-0 rating. The LOI test results further confirmed the excellent flame retardancy of PVA-PCSx, with LOI values substantially exceeding that of PVA film. Specifically, LOI values increased from 19.2% for PVA to 26.0%, 29.0%, and 31.3% for PVA-PCS8, PVA-PCS11, and PVA-PCS14, respectively (Fig. 3b).
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| Samples | TTI (s) | pHRR (kW/m2) | THR (MJ/m2) | Av-HRR (kW/m2) | Av-EHC (MJ/kg) | Residues (wt%) |
| PVA | 19 | 486.3 | 15.2 | 53.3 | 20.3 | 1.3 |
| PVA-PCS8 | 30 | 290.1 | 8.6 | 31.6 | 13.2 | 12.8 |
| PVA-PCS11 | 28 | 278.1 | 8.1 | 29.3 | 4.6 | 13.4 |
| PVA-PCS14 | 45 | 139.4 | 6.3 | 24.7 | 11.7 | 13.6 |
Cone calorimetry tests (CCT) simulating real fire scenarios were conducted to further evaluate the combustion behavior of PVA composite films. Figs. 3c and d present the CCT curves, while Table 1 summarizes the test data. The results indicated that all PVA-PCSx films had significantly extended time to ignition (TTI) compared to pure PVA. Notably, the TTI for PVA-PCS14 increased from 19s to 45s, which was the longest among all the samples tested. This indicated that a greater amount of heat input was required for the ignition of PVA-PCS14. This delay could be primarily attributed to the elimination reaction of hydroxyl groups in PVA. During this reaction, a significant number of water molecules were produced, which in turn increased combustion difficulty. The catalytic decomposition of PCS promoted dehydration, leading to advanced decomposition while delaying ignition [29]. Notably, the addition of PCS significantly decreased the heat release characteristics of PVA-PCSx films, as evidenced by reductions in the peak heat release rate (pHRR), total heat release (THR), and average heat release rate (Av-HRR). Specifically, PVA-PCS14 showed the lowest values: pHRR of 139.4 kW/m2, THR of 6.3 MJ/m2, and Av-HRR of 24.7 kW/m2, representing reductions of 71.3%, 58.6%, and 53.7%, respectively, compared to pure PVA. These reduced heat release values implied a diminished risk of fire hazards. Additionally, as illustrated in Fig. 3e, pure PVA burned almost completely, leaving only a minimal amount of ash (1.3 wt%). In contrast, PVA-PCSx film samples formed an expanded carbon layer during combustion, resulting in a significantly increased residues mass (12.8–13.6 wt%). This carbon layer functioned as an effective barrier, protecting the underlying PVA matrix from further combustion and significantly reducing the heat release rate. In conclusion, the incorporation of PCS promoted the formation of an expanded and dense carbon layer, thereby markedly enhancing the flame retardancy of PVA-PCS composite films.
To elucidate the flame-retardant mechanism, the current study performed a comparative analysis of the chemical composition and structure of the gas-phase products and condensed-phase char residuals derived from PVA and PVA-PCS14 films during pyrolysis or combustion. TG-IR analysis (Fig. 4) revealed that gaseous products from PVA-PCS14 were significantly reduced compared to pure PVA, indicating fewer combustible gases during combustion. No significant volatile gases were detected below 200 ℃ for either sample. As the temperature increased, both PVA-PCS14 and PVA films displayed characteristic absorption bands of typical gas-phase products, such as hydroxyl compounds (3500–3700 cm−1), hydrocarbons (2800–3200 cm−1), carbonyl compounds (1600–1850 cm−1), and carbon dioxide (2250–2400 cm−1) [30]. Additionally, prior studies demonstrated that PCS exhibited gas-phase flame retardant activity. It did do by generating PO· free radicals that captured the active HO and H free radicals released during combustion, thereby retarding the combustion process [31]. Unfortunately, due to the notable reduction in gas-phase products, the absorption bands associated with PO· radicals were significantly diminished. As a result, phosphorus-containing fragments were not distinguishable in the IR spectra.
SEM-EDX, XPS, and Raman spectroscopy were employed to analyze the microstructure and chemical composition of char residues from PVA and PVA-PCSx composite films after cone calorimetry testing. The results are summarized in Fig. 5. The SEM image (Figs. 5a-e) clearly indicated notable variations in the morphology of char residues between PVA and PVA-PCSx. The inner surface of the pure PVA residues was relatively smooth, while the inner surface of the PVA-PCS composite residues became notably rough. It should be particularly emphasized that numerous slender “needle-like” special microstructures were observed on the inner surface. As PCS content increased, these elongated “needle-like” structures became tightly interwoven and stacked, forming a fluffy micro-nano structure morphology. High-magnification SEM images revealed that these “needle-like” structures were composed of slender carbon nanosheets. Such a special morphology could be attributed to the catalytic effect of acidic substances such as phosphoric acid and pyrophosphate from PCS decomposition, which promoted carbonization and formed a protective carbon layer. Consequently, within a high-temperature anaerobic environment and under the catalysis of phosphoric acid, this layer experienced further graphitization under phosphoric acid catalysis, resulting in “needle-like carbon nanosheets”. Elemental mapping (Fig. 5f and Fig. S2a in Supporting information) uncovered uniform distribution of C, N, O, and P elements within the char layer, involving high concentrations of N (7.2%) and P (22.6%).
Through high-resolution XPS analysis (Fig. S2b in Supporting information), the elements C, N, O, and P were successfully identified. The C1s spectrum (Fig. 5g) showed a distinct π-π* transition peak, characteristic of sp2-hybridized carbon atoms in conjugated π bonds. Such a peak is commonly observed in carbonaceous materials such as carbon nanotubes and graphene. This further confirmed the presence of highly graphitized carbon in the residues, consistent with SEM results showing “needle-shaped carbon nanosheets”. Additionally, peaks at 284.8, 286.4, and 288.4 eV corresponded to C—C, C—O/C—N, and C=O bonds, respectively. The N 1s spectrum (Fig. 5h) revealed significant graphitic N (402.2 eV) and pyrrolic N (400.4 eV), indicating the deep involvement of nitrogen in the forming the condensed char layer [32]. Likewise, two characteristic peaks corresponding to P 2p1/2 and P 2p3/2 were observed in the phosphorus P 2p spectrum (Fig. 5i), indicating that phosphorus also played a crucial role in char formation [33]. Figs. 5j-l and Fig. S2c (Supporting information) present Raman spectra of PVA and PVA-PCSx char residues after CCT test, respectively. The D band at 1360 cm−1 and G band at 1580 cm−1 indicated disordered graphite vibrations and sp2-bonded carbon atom stretching, respectively. The ID/IG ratio could be used to evaluate the graphitization degree of carbon materials, with a lower ratio signifying higher graphitization. This was beneficial for enhancing flame retardancy by improving char residue stability [34,35]. The ID/IG values for PVA, PVA-PCS8, PVA-PCS11, and PVA-PCS14 were 3.26, 2.74, 2.51, and 2.55, respectively, demonstrating that PCS significantly improved graphitization [36]. Raman spectroscopy confirmed that PCS effectively promoted PVA dehydration and carbonization, forming a dense, well-ordered char layer. This aligned with SEM images showing “needle-like carbon nanosheets”, indicating PCS's significant condensed phase flame-retardant effect. Fig. 6 indicates the schematic diagram of the flame-retardant mechanism of PVA-PCS.
Fig. 7 shows the antibacterial activity of PVA and PVA-PCS films against Escherichia coli and S. aureus. The image (Fig. 7a) clearly demonstrated that the PVA film exhibited hardly any antibacterial activity, as evidenced by substantial microbial growth observed for both S. aureus and E. coli on the PVA plates. In contrast, the PVA-PCSx films showed nearly complete inhibition of bacterial growth, with almost zero colony counts, highlighting their excellent antibacterial properties. Specifically, Fig. 7b illustrated an antibacterial efficiency of up to 99.99% for all PVA-PCS films, attributed to the interaction between the positive charge in PCS and negatively charged bacterial cell membranes, leading to membrane disruption and protein leakage [37,38].
In conclusion, H3PO3-protonated chitosan derivatives (PCS) were hereby successfully synthesized, which served as a multi-hydrogen-bonding crosslinking agent and an efficient macromolecular flame retardant. This facilitated the preparation of high-performance PVA-PCSx composite films featuring enhanced mechanical strength, toughness, fire resistance, and antibacterial properties. PCS integrated acid, gas, and carbon sources, demonstrating superior gas-phase and condensed-phase flame-retardant mechanisms, especially in char formation. Consequently, PVA-PCS14 composites achieved an LOI value of 31.3%, UL-94 V-0 rating, and a 73.1% reduction in heat release rate. Hydrogen bonding interactions ensured excellent compatibility between PCS and PVA, forming a unique micro-nano mechanical interlocking interface structure. This resulted in superior transparency, enhanced Tgs, and robust mechanical properties. The strong hydrogen bonding networks and mechanical interlocking interface enhanced the composites' energy dissipation, increasing tensile strength by 51% to 115.6 MPa and fracture toughness by 107% to 81.6 MJ/m3. Additionally, PVA-PCSx composites inhibited E. coli and S. aureus by 99.99%. Overall, this work offers a promising strategy for designing mechanically robust and flame-retardant polymer materials using bio-based natural polysaccharides, aligning with circular economy and green chemistry principles.
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.
Xing Cao: Writing – original draft, Visualization, Resources, Methodology, Investigation, Formal analysis, Data curation. Xinyu Tian: Writing – original draft, Visualization, Resources, Methodology, Investigation, Formal analysis, Data curation. Yuanyuan Huang: Validation, Investigation, Data curation. Liping Zhang: Validation, Resources, Formal analysis. Yanpeng Ni: Writing – review & editing, Validation, Supervision, Project administration, Methodology, Funding acquisition, Formal analysis, Conceptualization. Yu-Zhong Wang: Writing – review & editing, Supervision, Project administration, Funding acquisition.
This work was financially supported by the National Natural Science Foundation of China (Nos. 51991351, 52173100), the Taishan Scholars Program (No. tsqn202312176) and the Youth Innovation Team Project of Shandong Province (No. 2022KJ304).
Supplementary material associated with this article can be found, in the online version, at doi:
B. Liu, R. Fu, Z. Duan, et al., Compos. Part B: Eng 236 (2022) 109804. doi: 10.1016/j.compositesb.2022.109804
X. Dong, X. Luo, X. Yang, et al., J. Colloid Interf. Sci. 672 (2024) 32–42. doi: 10.1016/j.jcis.2024.05.053
Y. Li, P. Ren, Z. Sun, et al., J. Colloid Interf. Sci. 669 (2024) 248–257. doi: 10.3390/vetsci11060248
J. Zhu, W. Qiu, C. Yao, et al., J. Colloid Interf. Sci. 603 (2021) 243–251. doi: 10.1016/j.jcis.2021.06.084
S. Qiu, Y. Zhou, X. Ren, et al., Chem. Eng. J. 402 (2020) 126212. doi: 10.1016/j.cej.2020.126212
H. Nabipour, S. Nie, X. Wang, L. Song, Y. Hu, Compos. Part A: Appl. Sci. Manufact. 129 (2020) 105720. doi: 10.1016/j.compositesa.2019.105720
Y. Ning, R. Liu, W. Chi, et al., Int. J. Biol. Macromol. 259 (2024) 129240. doi: 10.1016/j.ijbiomac.2024.129240
H. Liu, R. Chen, P. Wang, et al., Carbohydr. Polym. 316 (2023) 121050. doi: 10.1016/j.carbpol.2023.121050
W. Tan, L. Gao, J. Su, et al., Compos. Part A Appl. S. 177 (2024) 107897. doi: 10.1016/j.compositesa.2023.107897
C. Shi, M. Wan, J. Duan, et al., Compos. Part A Appl. S. 176 (2024) 107831. doi: 10.1016/j.compositesa.2023.107831
B.H. Wang, L.Y. Zhang, W.M. Song, Y. Liu, Int. J. Biol. Macromol. 276 (2024) 134002. doi: 10.1016/j.ijbiomac.2024.134002
X. Song, Z.P. Deng, C.B. Li, et al., Chin. Chem. Lett. 33 (2022) 4912–4917. doi: 10.1016/j.cclet.2021.12.067
P. Song, Z. Xu, M.S. Dargusch, et al., Adv. Mater. 29 (2017) 1704661. doi: 10.1002/adma.201704661
P. Song, J. Dai, G. Chen, et al., ACS Nano 12 (2018) 9266–9278. doi: 10.1021/acsnano.8b04002
P. Song, Z. Xu, Y. Lu, Q. Guo, Macromolecules 48 (2015) 3957–3964. doi: 10.1021/acs.macromol.5b00673
X. Xu, L. Li, S.M. Seraji, et al., Macromolecules 54 (2021) 9510–9521. doi: 10.1021/acs.macromol.1c01725
G. Li, Q. Yan, H. Xia, Y. Zhao, ACS Appl. Mater. Interfaces 7 (2015) 12067–12073. doi: 10.1021/acsami.5b02234
S. Batool, W. Guo, R. Gill, W. Xin, Y. Hu, Carbohydr. Polym. 291 (2022) 119488. doi: 10.1016/j.carbpol.2022.119488
Y. Xiong, Z. Fang, P. Tang, et al., Carbohydr. Polym. 348 (2025) 122879. doi: 10.1016/j.carbpol.2024.122879
S. Xiang, C. Chen, F. Liu, et al., J. Colloid Interf. Sci. 669 (2024) 775–786. doi: 10.1016/j.jcis.2024.05.060
W. Xie, Q. Bao, Y. Liu, H. Wen, Q. Wang, ACS Appl. Mater. Interf. 13 (2021) 5508–5517. doi: 10.1021/acsami.0c19093
J. Lu, Q. Liu, Y. Zhang, Y. Zhou, Y. Zhou, Chin. Chem. Lett. 35 (2024) 109406. doi: 10.1016/j.cclet.2023.109406
B. Fu, Q. Liu, M. Liu, et al., Chin. Chem. Lett. 33 (2022) 4577–4582. doi: 10.1016/j.cclet.2022.03.048
Y. Wang, J. Yuan, L. Ma, et al., Carbohydr. Polym. 298 (2022) 120141. doi: 10.1016/j.carbpol.2022.120141
W. Tang, G. Liang, L. Wang, et al., J. Clean. Prod. 394 (2023) 136371. doi: 10.1016/j.jclepro.2023.136371
X. Liu, X. Gu, J. Sun, S. Zhang, Carbohydr. Polym. 167 (2017) 356–363. doi: 10.1016/j.carbpol.2017.03.011
X. Liu, C. Xiao, Environ. Technol. Innov. 20 (2020) 101087. doi: 10.1016/j.eti.2020.101087
X.L. Li, X.H. Shi, M.J. Chen, et al., Cellulose 29 (2022) 5289–5303. doi: 10.1007/s10570-022-04566-x
Y. Luo, D. Xie, Y. Chen, et al., Polym. Degrad. Stab. 170 (2019) 109019. doi: 10.1016/j.polymdegradstab.2019.109019
Y. Xu, C. Yan, C. Du, et al., Compos. Part B: Eng. 261 (2023) 110809. doi: 10.1016/j.compositesb.2023.110809
X. Cao, Y.Y. Huang, X.Y. Tian, Y.P. Ni, Y.Z. Wang, Int. J. Biol. Macromol. 300 (2025) 140205. doi: 10.1016/j.ijbiomac.2025.140205
P. Lazar, R. Mach, M. Otyepka, J. Phys. Chem. C 123 (2019) 10695–10702. doi: 10.1021/acs.jpcc.9b02163
B. Wang, C.Y. Luo, P. Zhu, Y. Liu, Y.J. Xu, Prog. Org. Coat. 184 (2023) 107864. doi: 10.1016/j.porgcoat.2023.107864
Y.M. Li, W.J. Hu, S.L. Hu, Y.R. Li, D.Y. Wang, Chem. Eng. J. 474 (2023) 145803. doi: 10.1016/j.cej.2023.145803
K.N. Kudin, B. Ozbas, H.C. Schniepp, et al., Nano Lett. 8 (2008) 36–41. doi: 10.1021/nl071822y
Z. Zhang, Z. Zhou, J. Huang, Y. Wang, J. Mater. Chem. A 12 (2024) 6050–6066. doi: 10.1039/d3ta07522b
S. Lee, M. Zhang, G. Wang, et al., Carbohydr. Polym. 262 (2021) 117930. doi: 10.1016/j.carbpol.2021.117930
F. Liu, X. Zhang, X. Xiao, et al., Carbohydr. Polym. 312 (2023) 120755. doi: 10.1016/j.carbpol.2023.120755
Figure 1 (a) Synthesis route of PCS and fabrication process of PVA-PCSx composite films. (b) FT-IR spectra of CS, PCS, PVA, and PVA-PCS14. (c) The 1H NMR and 31P NMR spectra of PCS. (d) Digital photos and UV–vis transmittance spectra. (e) FT-IR spectra, (f) TEM diagram and (g) AFM image of PVA and PVA-PCSx composite films.
Figure 2 (a) DSC curves of PVA and PVA-PCSx composite films. Mechanical properties of PVA and PVA-PCSx composite films: (b) Stress-strain curves, (c) tensile strength and elongation at break, (d) toughness, (e) TGA, and (f) DTG curves of PVA and PVA-PCSx composite films.
Figure 3 (a) Digital photographs of PVA and PVA-PCSx composite films during UL-94 test. (b) UL-94 ratings and LOI values of PVA and PVA-PCSx composite films. (c) Heat release rate curves over time from the CCT test. (d) THR results from the CCT test. (e) Digital image of char residues derived from PVA and PVA-PCSx composites.
Figure 4 (a, b) 3D TG-IR spectra of PVA and PVA-PCS14. (c, d) FT-IR spectra of PVA and PVA-PCS14 acquired at various temperatures.
Figure 5 SEM (a-e) of the residue of PVA-PCSx composites film, element distribution (f) of the residue of PVA-PCS14 sample, (g) C 1s, (h) N 1s, and (i) P 2p spectra of residues char for PVA-PCS14 in XPS test, Raman spectra of char residues of (j) PVA, (k) PVA-PCS11, and (l) PVA-PCS14 after CCT.
Figure 7 (a) Digital images of the colony formation of S. aureus and E. coli on agar plates following incubation with various samples. (b) Antibacterial rate of PVA and PVA-PCS films against S. aureus and E. coli.
Table 1. Detailed results for PVA and PVA-PCSx composites obtained from cone calorimeter test.
| Samples | TTI (s) | pHRR (kW/m2) | THR (MJ/m2) | Av-HRR (kW/m2) | Av-EHC (MJ/kg) | Residues (wt%) |
| PVA | 19 | 486.3 | 15.2 | 53.3 | 20.3 | 1.3 |
| PVA-PCS8 | 30 | 290.1 | 8.6 | 31.6 | 13.2 | 12.8 |
| PVA-PCS11 | 28 | 278.1 | 8.1 | 29.3 | 4.6 | 13.4 |
| PVA-PCS14 | 45 | 139.4 | 6.3 | 24.7 | 11.7 | 13.6 |
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