水在灭火过程中易汽化和流失。温敏性水凝胶在常温下呈溶胶状具有一定流动性，高温下发生相变形成凝胶，提高水的黏附性以改善其灭火性能。多孔结构的比表面积大，可促进水凝胶内的分子运动，进一步提升相变响应速率和载水性。本文制备羟丙基甲基纤维素/聚乙二醇/壳聚糖（HPMC/PEG/CS）温敏性多孔水凝胶，研究其相变规律、成胶特性及抑制木材燃烧过程。

以醋酸/碳酸钠（CH₃COOH/Na₂CO₃）作为致孔剂，采用物理交联法制备了HPC多孔水凝胶，分析水凝胶的相变规律，研究其结构特性。HPMC、PEG、CS和致孔剂均可提升水凝胶的温敏凝结能力并减小相变响应时间。当HPMC黏度规格为30 mPa·s且含量为3 wt%、CS含量为0.4 wt%、PEG含量为1.5 wt%、CH₃COOH/Na₂CO₃含量为0.375 wt%/0.3 wt%时，水凝胶具有良好的流动性和温敏性，相变后凝胶骨架稳定且呈多孔结构。表观粘度较小，相变响应时间由256 s减小至28 s，比表面积增加了15.4425 m²·g⁻¹。

采用FT-IR、DSC和旋转流变仪分析水凝胶分子间交联方式、相变过程和流变规律。水凝胶中HPMC、CS和PEG分子通过氢键和链靠拢缠结作用形成了稳定的三维网络。在相变过程中，疏水性甲氧基形成疏水域并产生去水化作用，促进分子链卷曲收缩形成凝胶。多孔结构包拢大量稳定的结合水提高了水凝胶的载水性、稳定性和粘弹性，水凝胶在屈服应力作用下为剪切稀化的屈服假塑性流体，与HPC水凝胶相比，HPC多孔水凝胶在130~160 ℃内吸热焓值增加了241.38 J·g^-1，相变后凝胶的释水时间延迟了252 s。

研究了HPC多孔水凝胶抑制木材燃烧特性。通过热稳定性、接触角和表面张力分析水凝胶在木材表面的润湿与黏附性，采用激光导热装置和TG-DSC联用技术分析水凝胶对木材热传导特性、热解过程和放热特征的影响。20 wt%浓度的水凝胶具有良好的铺展润湿性，在木材表面可快速铺展并形成溶胶膜，相变后形成块状凝胶层，具有良好热稳定性、黏附性和润湿性，可隔绝氧气并抑制复燃。同时，水凝胶可降低木材的热传导能力、燃烧特性参数和热解放热，提高木材的热惰性，延缓木材燃烧热解过程和放热强度。

Water is susceptibility to vaporization and rapid loss in high-temperature fire conditions. The thermosensitive hydrogels are pre-gels at ambient temperature with fluidity and form adhesive gels after phase transition, which can improve the viscosity of water and fire extinguishing performance. The porous structure with a large specific surface area can promote the movement of molecules, and further improve the response rate of phase transition and water-carrying capacity of hydrogels. In this study, a thermosensitivity porous hydrogel composed of hydroxypropyl methylcellulose/polyethylene glycol/chitosan (HPMC/PEG/CS) was prepared and characterized with respect to the laws of phase transition, gelation properties and inhibition properties on wood combustion.

The HPC porous hydrogel was successfully synthesized by physical crosslinking incorporating Na₂CO₃/CH₃COOH as porogen. The influence of each component on the law of hydrogel phase transformation was analyzed. The structural properties were characterized. The addition of HPMC, PEG, CS, and porogen improved the thermosensitivity and decrease the phase transition response time of HPC porous hydrogels. The optimal composition ratio consisted of HPMC with a specification of 30 mPa·s and an additional amount of 3 wt%, CS with an additional amount of 0.4 wt%, PEG with an additional amount of 1.5 wt%, and CH₃COOH/Na₂CO₃ with an additional amount of 0.375 wt%/0.3 wt%. Hydrogel demonstrated good fluidity and thermosensitivity. The porous framework of the gel exhibits excellent stability after phase transition. The phase transition response time of hydrogel decreased from 256 s to 28 s. The specific surface area increased by 15.4425 m²·g⁻¹.

The FT-IR, DSC, and rotary rheometer were employed to explore the intermolecular crosslinking mode, the process of phase transition, and the rheological law of HPC porous hydrogels. HPMC, CS, and PEG formed a stable three-dimensional network through hydrogen bonding and molecular chain entanglement to form hydrogels. In the process of phase transition, hydrophobic domains were formed by methoxy movement. hydrophobic methoxy group forms hydrophobic water and generates dehydration, which promoted molecular chain curling to form gels. The porous structure enclosed a large amount of bound water to enhance the water-retaining capacity, stability, and viscoelasticity of HPC porous hydrogels. The hydrogel system exhibited shear-thinning-yield pseudoplastic fluid behavior with yield stress. In comparison to HPC hydrogels, the endothermic enthalpy was increased by 241.38 J·g^-1 at 130~160 ℃ and the water release time of the gel was delayed by 252 s after the phase transition.

The inhibition of wood combustion of HPC porous hydrogel was investigate. The thermostability, contact angle and surface tension were analyzed to evaluate the wettability and adhesivity of the HPC porous hydrogel. The impact on wood heat conduction, pyrolysis process, and exothermic characteristics was examined using laser heat conduction and TG-DSC. 20 wt% HPC porous hydrogel exhibited optimal spreadability and wettability in the pre-gel state, which could can spread quickly and form sol film on the surface of wood. The massive gel layers following the phase transition displayed optimal thermal stability, adhesivity and wettability to isolate oxygen and inhibit reignition. In addition, the diluent could reduce the heat conduction capacity, combustion characteristic parameters and pyrolytic heat release of wood to enhance the thermal inertness of wood, and delay the pyrolysis process and heat release intensity of wood.