Flammable textile materials, including cotton fabrics, are responsible for 20% of fire-related disasters. Studies focused on enhancing the flame-retardant properties of cotton fabrics have garnered considerable attention (Makhlouf, Abdelkhalik, & Ameen, 2021; Zhicai Yu et al., 2021). Therefore, the identification of highly cost-effective and environmental-friendly methods for reducing the flammability of cotton fabric materials is crucial for public safety (Q.-L. Li et al., 2018). Several applications necessitate the integration of advanced smart functionalities into textile fabrics for achieving unique characteristics, such as enhanced thermal stability, flame retardancy and antibacterial protection. The development of multifunctional textiles that possess both flame-retardant and antibacterial properties will help enhance safety by creating barriers against fire and health hazards, improving the protection of individuals and property (Dongqiao et al., 2017; Zhou, Chen, Lu, Tian, & Shao, 2022). The adoption of novel alternative chemicals is gaining increasing interest for developing environmentally friendly textiles, which are commonly referred to as ‘green textiles’ or ‘eco-friendly textiles’.
The flame retardancy of cotton fabrics have been improved using diverse types of materials. For instance, (a) Attia et al. (2020) utilised various nanoparticle materials to enhance the thermal stability, flame retardancy and antibacterial properties of textiles. However, the incorporation of nanoparticles into fibres negatively affected the tensile strength of the treated textile fabrics. (Attia, Soliman, & El-Sakka, 2020). (b) Zhang et al. (2021) demonstrated that halogenated compounds, including pentabromodiphenyl ether, decabromodiphenyl ether and polychlorinated biphenyls, possess effective flame-retardant properties. However, the use of these compounds has been restricted in several countries because of their hazardous effects on humans and animals, leading to extensive scrutiny and regulatory measures (Zhang et al., 2021). (c) Goutham et al. (2022) proposed metal hydroxides, such as Al(OH)₃ and Mg(OH)₂, as alternatives to halogenated flame retardants because of their ability to absorb considerable amounts of heat at high temperatures. However, to achieve effective flame retardancy, high concentrations of metal hydroxides are required, which negatively impacts the mechanical properties of the resulting materials (Goutham et al., 2022). (d) Rosace et al. (2017) developed several organophosphorus-based flame retardants, including phosphates, phosphoramides, phosphonates and phosphonium salts; however, only a few of these materials were successful (Rosace, Colleoni, Guido, & Malucelli, 2017). Previous studies have commonly focused on inorganic antibacterial agents, such as Ag and Cu nanoparticles, which possess broad-spectrum and high-efficiency antibacterial properties. However, the potential damage caused by the release of nanoscale metals into the environment is a considerable issue (Gao, Su, Wang, Fu, & Wang, 2021).
In the past decade, ionic salts have emerged as a fast-developing area of chemical research focused on new materials (Abeysooriya, Lee, Hwan Kim, O'Dell, & Pringle, 2023). Multidisciplinary studies on ionic salts are emerging in fields such as chemistry, material science, chemical engineering and environmental science (Lei, Chen, Koo, & MacFarlane, 2017; Nusaibah Masri, Mutalib Mi, & Leveque, 2016). The superior efficiency, higher performance and lower hazard risks of ionic salts enable them to replace conventional organic solvents in numerous processes (Kaur, Kumar, & Singla, 2022). Compared with monocationic ionic salts, dicationic ionic salts have higher thermal and chemical stability, higher solubility of compounds, enhanced surface properties and lower volatility (Cao, Tan, Wang, & Yuan, 2021). Triazole-containing compounds have been widely utilised in pharmaceuticals because of their diverse biological activities, such as antibacterial, anti-tuberculosis, anti-human immunodeficiency virus and alpha-glucosidase inhibition properties (Czerniak, Gwiazdowski, Marcinkowska, & Pernak, 2019). Triazolium cations are suitable for synthesising specialised ionic salts for ‘fully organic’ applications (Ruihu Wang, 2007). Furthermore, hydrogels are promising flame-retardant materials owing to their ability to prevent water loss and form protective layers (Yu, Liu, He, Ma, & Yao, 2021). When exposed to fire, water in the hydrogels gradually evaporates, absorbing heat and delaying the combustion process (Ingtipi, Choudhury, & Moholkar, 2023; Zhicai Yu et al., 2021). Therefore, the combination of hydrogels with cotton fabrics can reduce the flammability of the resulting textile materials when exposed to fire. Additionally, the hydrogels containing various antibiotics and antibacterial agents have the ability to kill bacteria and prevent infections when used in textile materials (Yaman Turan, Korcan, & Aydin, 2024).
This study aimed to synthesise novel triazolium salts, both dicationic and monocationic salts, for preparing triazolium-based ‘green’ hydrogels. Furthermore, we evaluated the flame-retardant and antibacterial properties of the novel triazolium-containing hydrogels applied to cotton fabrics. Thermal stability is a critical factor that influences their flame-retardant treatment. Understanding the thermal degradation behaviour is important for analysing the flame-retardant properties and charcoal mechanism of the synthesised materials (Y. Li, Qiang, Chen, & Ren, 2019). The Kissinger–Akahira–Sunose (K–A–S), Flynn–Wall–Ozawa (F–W–O) and Starink kinetic methods were applied to study the activation energy of the synthesised flame retardants. Furthermore, this paper focuses on the thermal degradation kinetics of triazolium ionic salts and discusses the effects of activation energy on the triazolium hydrogel-treated cotton fabrics for achieving efficient flame retardancy.