Wettability of HPMC/PEG/CS Thermosensitive Porous Hydrogels

Abstract

Thermosensitive hydrogels have been receiving attention in the development of fire extinguishing agents due to their stimuli responsivity. Conventional hydrogels are limited by their slow response rate, and their wettability has not been studied systematically. In the present study, a concentrate of a thermosensitive porous system has been successfully synthesized by adding Na2CO3/CH3COOH as a foaming agent into the mixture of hydroxypropyl methylcellulose (HPMC)/polyethylene glycol (PEG)/chitosan (CS). The systems with different concentrations were obtained by diluting the concentrate with water. Thermosensitivity, surface tension and contact angle were characterized. In addition, spreadability, wettability and adhesivity were investigated systematically. Results showed that the systems with a concentration greater than 15 wt% exhibited outstanding performance of thermosensitivity and coagulability. A total of 20 wt% of the system has the best spreadability and wettability on the wood surface, most likely due to favorable contributions brought by both adequate viscosity and hydrophilicity. The adhesive force and surface-free energy of the pre-gel droplet that reached deposition on the wood surface decreased by 46.78% and 20.71%, respectively. The gel has a great capacity of water retention over a long period of time, which makes this porous gel the best system when it comes to its wettability and adhesiveness towards the chosen wood surface. The equilibrium surface tension decreased by 45.50% compared with water. HPMC/PEG/CS thermosensitive porous hydrogel with excellent wettability presented wide-ranging possibilities for the further development of fire suppression agents of fast phase-transition thermosensitive hydrogel.

Deswelling Mechanisms of PNIPAM Grafted in Nanochannels: A Molecular Dynamics Simulation Study

“…These materials can absorb moisture from the air, equivalent to many times their own weight and can generate pure liquid water when exposed to sunlight, leveraging their thermosensitive characteristics. Concentrated solutions of porous hydroxypropyl cellulose (HPC)-based thermosensitive hydrogels were prepared by physical cross-linking by Ma et al These findings provided a theoretical basis for the preparation of new fire extinguishing agents based on the rapid release features of a thermosensitive porous water gel.…”