Alkylamine-Grafted Chitosan Bio-based Phase Change Material: Addressing Leakage and Insufficient Thermal Stability Issues

Defects such as leakage and insufficient thermal stability in phase change materials (PCMs) have limited their further application in thermal energy storage. Although physical encapsulation may alleviate the problems, it is not a fundamental solution compared to chemical grafting methods. As a natural biopolymer, chitosan (CS) has emerged as a promising carrier for functional material modification due to its abundant reactive groups and inherent biocompatibility. This study synthesized bio-based solid-solid PCMs OP and HP by grafting phase change units octadecylamine (ODA) and hexadecylamine (HDA) onto CS. FTIR and XRD tests confirmed successful grafting from microstructural perspectives. The grafting ratios (GR) of OP and HP range from 33.08±5.44% to 148.96±5.70%, with the grafting efficiency (GE) reaching up to 89.6±4.17%. When the CS molecular weight is 300,000, the crosslinker dosage is 10 ml, ODA dosage of 9.15 g, and HDA dosage of 8.20 g, the exothermic latent heat of OP30-1 and HP30-1 are 128.46±4.1 J/g and 104.33±3.6 J/g, respectively, with thermal conductivities of 0.3007±0.0101 W·(m·K) -1 and 0.1434±0.0055 W·(m·K) -1 . After 500 thermal cycles at 0 ℃-60 ℃, the materials retain over 90% of their heat storage capacity with low mass loss (≤1.585 wt%). Due to restricted molecular motion within the crosslinked network, the thermal decomposition temperatures of OP and HP increased by 38.3-83.1 ℃ compared to pure ODA and HDA, demonstrating satisfactory thermal stability. OP and HP series materials demonstrate application potential in overcoming multiple bottlenecks of PCMs and developing high-performance environmentally friendly materials, providing sustainable solution for energy storage.