An Environmentally Friendly Phosphorus-Modied Cellulose/Silica Hybrid Hydrogel for Fire Prevention and Fireghting Hafezeh Nabipour University of Science and Technology of China Hu Shi University of Science and Technology of China Xin Wang ( [email protected] ) University of Science and Technology of China https://orcid.org/0000-0001-5881-4400 Xiangming Hu Shandong University of Science and Technology Lei Song University of Science and Technology of China Yuan Hu University of Science and Technology of China Research Article Keywords: Cellulose-based hydrogel, Organic-inorganic hybrid, Fire prevention, Fireghting Posted Date: February 26th, 2021 DOI: https://doi.org/10.21203/rs.3.rs-184642/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License 1 An Environmentally Friendly Phosphorus-Modified Cellulose/Silica Hybrid 2 Hydrogel for Fire Prevention and Firefighting 3 Hafezeh Nabipour a, Hu Shi a, Xin Wang a,*, Xiangming Hu b, Lei Song a, Yuan Hu a,* 4 a State Key Laboratory of Fire Science, University of Science and Technology of 5 China, 96 Jinzhai Road, Hefei, Anhui 230026, P. R. China. 6 b Key Lab of Mine Disaster Prevention and Control, College of Mining ad Safety 7 Engineering, Shandong University of Science and Technology, Qingdao, Shandong 8 266590, P. R. China. 9 *Corresponding authors. Tel/Fax: +86-551-63601664. E-mail address: 10 [email protected] (Y. Hu), [email protected] (X. Wang). 11 Abstract 12 Wildfires have been recognized as a natural incident in some forests, however, fire 13 season is now more severe and extensive, even in tropical rainforests in which fire could 14 have damaging impacts. A hydrogel is a 3-D polymeric structure encompassing cross- 15 linked and hydrophilic macromolecules. In comparison with water, hydrogels have 16 shown some superiorities in terms of water-binding, cooling, and sealing, which make 17 them be applied in forest fire prevention programs for improving fire-extinguishing 18 performance. In this study, an environmentally friendly phosphorus-modified 19 cellulose/silica hybrid hydrogel was prepared based on the modified methylcellulose 20 by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide–itaconic acid (DOPO-ITA) 21 and silica nanoparticles. The storage (G') and loss (G") moduli increased with the 22 increment of silica nanoparticles content, owing to the role of silica nanoparticles as 1 23 crosslinking agent. In the fire prevention experiments, the grass treated with the 24 methylcellulose@DOPO-ITA@silica hybrid hydrogel shows self-extinguishing 25 behavior, whereas those treated with ordinary water or methylcellulose hydrogel can 26 be easily ignited after one week. In the firefighting experiments, the 27 methylcellulose@DOPO-ITA@silica hybrid hydrogel displays much shorter 28 extinguishing time and lower consumption volume than ordinary water and the 29 methylcellulose@DOPO-ITA hydrogel. This work presents an environmentally- 30 friendly, non-toxic, and biodegradable cellulose-based hybrid hydrogel for fire 31 prevention and firefighting of wildfires. 32 Keywords: Cellulose-based hydrogel, Organic-inorganic hybrid, Fire prevention, 33 Firefighting 34 35 1. Introduction 36 Forest fires occur around the world, particularly in Australia, Canada, China, the 37 USA, and Russia every year, the far-reaching consequences of which represent a global 38 challenge that can have destructive effects on the environmental benefit of the forest 39 and pose deadly threats on the animal and human life (Adámek, Hadincová, & Wild, 40 2016; Chandra & Bhardwaj, 2015; Tymstra, Stocks, Cai, & Flannigan, 2020). The 41 severity, frequency and efficacy of wildland fires and wildland-urban interface (WUI) 42 fire phenomena have been growing in recent years (Manzello et al., 2018). The southern 43 California fire resulted in the displacement of more than 300,000 persons, the 44 destruction of over 1000 buildings, and US $1 billion compensation paid by insurances 2 45 only in 2007 (Annual Report of the Insurance Commissioner, 2007). The 2009 46 Australian Black Saturday bushfires resulted in the death of 173 people and US$4 47 billion loss (Teague, Mcleod, & Pascoe, 2010). More than 150 people were killed and 48 more than 2000 structures were destroyed by the 2009 fire in Victoria, Australia. In 49 2017, forest fires in California caused to the death of at least 42 persons and the 50 destruction of more than 7000 structures. In 2018, California faced a huge harm once 51 more due to the WUI fires, which killed more than 80 people and destroyed almost 52 19,000 buildings. More than 6 million hectares of the Australian forests were burned in 53 the late 2019 WUI fire which continued for four months causing at least 28 deaths, and 54 more than 2000 damaged structures (Jiang et al., 2021). More recently, an area near the 55 size of Syria is burnt in the 2019–2020 wildfire season (Center for Disaster 56 Philanthropy, 2020). The surface vegetation can be destroyed due to the large-scale 57 forest fires resulting in terrific damages in the local ecological environment threatening 58 the lives of wild animals. Furthermore, forest fires can significantly influence human 59 lives, specifically in WUI zones, comprising direct property losses as well as health 60 problems induced by air and water pollution. 61 Over the past few decades, rescue worker and scientific expertise get together in a 62 team effort to develop efficient technologies for bringing forest fires under control 63 (Korobeinichev et al., 2012). Water has the potential for absorbing a large quantity of 64 heat produced from thermal evaporation process, due to its large specific heat capacity 65 (Vega et al., 2010) and high latent heat of evaporation (Torquato & Stell, 1981). Water 66 is mostly used as a fire extinguisher from antiquity to the present day. On contact with 3 67 flammable materials, water naturally produces an oxygen barrier performance to 68 prevent fires and explosions. Given the changing shape of water at room temperature, 69 its direct exploitation as a material completely resistant to fire is a difficult work. 70 Besides using water directly, the intensity and spread rate of wildland fires can be 71 reduced by fire retardants so that on-ground firefighters can enter to the area creating 72 safer containment lines close the fire (Agueda, Pastor, & Planas, 2008). North America, 73 Australia and the Mediterranean basin countries have extensively utilized fire retardants 74 to battle forest fires. The fire retardants fall into two categories of short- and long-term. 75 Foam is an example of short-term retardants. It is a cheap alternative that enables 76 water to douse the flames with an increased efficiency. The effectiveness of foam is of 77 shorter duration than long-term retardants (Liodakis, Tsapara, Agiovlasitis, & Vorisis, 78 2013). For long-term retardants, the solving water plays a secondary role as a carrier 79 medium enabling the retardant product to get access to the fuel. These chemicals can 80 hinder the flame modifying the combustion processes; they can remain active even after 81 the evaporation of all the water. The key active components in the long-term retardants 82 include inorganic salts (ammonium phosphates and ammonium sulfates), while the 83 thickening and coloring agents as well as corrosion inhibitors are also contained in the 84 formulations (Kalabokidis, 2000). Among long-standing retardants which inhibit forest 85 fires, diammonium phosphates, monoammonium phosphates as well as ammonium 86 sulphates have been widely utilized across the world. However, the fire prevention and 87 firefighting techniques with higher efficiency and ecological compatibility are still 88 required. 4 89 Hydrogels constitute a group of polymers having a 3D crosslinked structure and 90 a hydrophilic nature at the macromolecular level (Azizi, Mohamad, Abdul Rahim, 91 Mohammadinejad, & Bin Ariff, 2017; Ibrahim, Nawwar, & Sultan, 2016; Kim & Shin, 92 2007; Thakur, Chaudhary, Kumar, & Thakur, 2019). They are more advantageous than 93 pure water, in terms of water binding, cooling, and sealing abilities. Compared to 94 conventional fire extinguishers (e.g., nitrogen and water), hydrogels make a reduction 95 in temperature, dose of thermal radiation, and CO production by forming an additional 96 layer upon flammable materials. It remarkably improves their performance in 97 controlling the spontaneous combustion reaction of coal. In recent years, hydrogels are 98 widely used materials for preventing forests, buildings, and cloth from fire (Fan, Zhao, 99 Hu, Wu, & Xue, 2020; Giudice, Alfieri, & Canosa, 2013; Illeperuma, Rothemund, Suo, 100 & Vlassak, 2016; Vinogradov et al., 2016). 101 Qin et al. developed multiphase gel as a synthetic foaming material to promote 102 their efficiency in extinguishing the fire (Zhang & Qin, 2014). Vinogradov et al. 103 introduced ultrafast-gelated foam whose solidification needs a time less than 30 s 104 (Vinogradov et al., 2016). They used silica gel for giving a long-term stability to the 105 foam, with which the surface of flammable substrate was covered. It became especially 106 applicable for forest fires. According to their results, the flame-retardant efficiency of 107 silica-based sol-gel foams was 50 and 15 times greater than those of ordinary water and 108 the latest aqueous foams, respectively. Sou et al. designed a sample of hybrid hydrogels 109 containing polyacrylamide and sodium alginate (Illeperuma et al., 2016). They 110 prepared hydrogel-fabric laminates by sewing the hydrogel samples to a commercial 5 111 aramid textile fiber. The laminates were highly resistant to fire. They achieved a real 112 potential for being a life saver since they decreased temperature to a range acceptable 113 for human skin. The preparation of highly water-absorbent gels by natural polyhydroxy 114 materials covers the subject of many research studies in the present, due to the 115 environment friendly and economical technology. Methylcellulose (MC) as a 116 commonly used biomedical material is chemically derived from cellulose.