Institute of Polymers, Bulgarian Academy of Sciences, Akad. G. Bonchev st. 103A, 1113 Sofia, Bulgaria.
Molecules. 2021 Oct 21;26(21):6370. doi: 10.3390/molecules26216370.
Biopolymer materials have been considered a "green" alternative to petroleum-based polymeric materials. Biopolymers cannot completely replace synthetic polymers, but their application should be extended as much as possible, exploiting the benefits of their low toxicity and biodegradability. This contribution describes a novel strategy for the synthesis of super-macroporous 2-hydroxyethylcellulose (HEC) cryogels. The method involves cryogenic treatment of an aqueous solution of HEC and citric acid (CA), freeze drying, and thermally induced crosslinking of HEC macrochains by CA in a solid state. The effect of reaction temperature (70-180 °C) and CA concentration (5-20 mass % to HEC) on the reaction efficacy and physico-mechanical properties of materials was investigated. Highly elastic cryogels were fabricated, with crosslinking carried out at ≥100 °C. The storage modulus of the newly obtained HEC cryogels was ca. 20 times higher than the modulus of pure HEC cryogels prepared by photochemical crosslinking. HEC cryogels possess an open porous structure, as confirmed by scanning electron microscopy (SEM), and uptake a relatively large amount of water. The swelling degree varied between 17 and 40, depending on the experimental conditions. The degradability of HEC cryogels was demonstrated by acid hydrolysis experiments.
生物聚合物材料被认为是石油基聚合材料的一种“绿色”替代品。生物聚合物不能完全替代合成聚合物，但应尽可能扩大其应用范围，利用其低毒性和可生物降解性的优势。本贡献描述了一种合成超微孔 2-羟乙基纤维素（HEC）冷冻凝胶的新策略。该方法涉及 HEC 和柠檬酸（CA）水溶液的低温处理、冷冻干燥以及 CA 在固态下对 HEC 大分子链的热引发交联。研究了反应温度（70-180°C）和 CA 浓度（HEC 的 5-20 质量%）对反应效率和材料的物理力学性能的影响。制备了高弹性的冷冻凝胶，交联温度≥100°C。新获得的 HEC 冷冻凝胶的储能模量比通过光化学交联制备的纯 HEC 冷冻凝胶的模量高约 20 倍。扫描电子显微镜（SEM）证实 HEC 冷冻凝胶具有开放多孔结构，并能吸收相对大量的水。溶胀度根据实验条件在 17 到 40 之间变化。通过酸水解实验证明了 HEC 冷冻凝胶的可降解性。
