For porous materials prepared via the ice template method, the growth law of ice crystals exerts a significant influence on the formation of their pore structure. In this study, the growth rate and rapid growth process of ice crystals in the raw material solution of chitosan cryogels were simulated. Firstly, the freezing point of the chitosan solution was determined using differential scanning calorimetry (DSC), and a solidification-melting phase equilibrium model was constructed. Secondly, the growth rate of ice crystals (ICGR) in the chitosan solution was measured via molecular dynamics simulations. Based on the simulation data, an improved empirical model was established, which can describe the effects of temperature and multi-component concentration on the ICGR. Finally, using the self-developed model, simulations and predictions were conducted on the dynamic change rules of ice crystal size during the rapid growth stage, the expansion dynamics of the solid-liquid interface near the wall, and the position of ice crystal grain boundaries during the competition of multiple crystal nuclei. Relevant studies indicate that the determination of the ice crystal interface based on the cumulative function of relative density deviation is objective and accurate. Fitting the ICGR in multi-component solutions based on the degree of solvent supersaturation is reasonable and feasible. The initial crystallization temperature, solution concentration, and differences in initial crystallization time have significant effects on the growth dynamics and ice crystal control zone size during the rapid growth stage. The ICGR model proposed in this study can provide necessary theoretical support for simulating the rapid growth stage of ice crystals and also lay a solid foundation for further exploring the crystal growth process in the chitosan solution and the pore structure formation rules of cryogels. • Proposed a more objective and precise method for determining the liquid-solid interface in molecular simulations. • Developed a mathematical model to account for the effects of multi-component solute concentrations and temperature. • Predicted the rapid growth process of ice crystals in the chitosan solution.
Chen et al. (Fri,) studied this question.