Chen Pei, Xie Fengwei, Tang Fengzai, McNally Tony
College of Food Science, South China Agricultural University, Guangzhou, Guangdong 510642, China.
International Institute for Nanocomposites Manufacturing (IINM), WMG, University of Warwick, Coventry CV4 7AL, United Kingdom.
ACS Appl Polym Mater. 2020 Jul 10;2(7):2957-2966. doi: 10.1021/acsapm.0c00433. Epub 2020 Jun 17.
This work describes the effects of different plasticizers, namely, glycerol, triacetin, and 1-ethyl-3-methylimidazolium acetate ([C mim][OAc]), on the structure and properties of thermomechanically processed, bulk chitosan and chitosan/alginate materials. Mechanical data shows that, for the chitosan matrix, glycerol and [C mim][OAc] were highly effective at reducing intra- and intermolecular forces between biopolymer chains, leading to increased ductility, while the plasticization effect of triacetin was minor. Nonetheless, this triester effectively suppressed biopolymer recrystallization, whereas [C mim][OAc] promoted it. In contrast, for the chitosan/alginate matrix, inclusion of triacetin resulted in increased recrystallization, higher thermal stability, and excellent mechanical properties. The triacetin assisted the interactions between biopolymer chains in this polyelectrolyte complexed system. In contrast, the chitosan/alginate material plasticized by [C mim][OAc] displayed the most apparent phase separation, poorest mechanical properties, and highest surface hydrophilicity, behavior associated with the disruption of polyelectrolyte complexation and hydrogen bonding between biopolymer chains. Interestingly, the formation of a "new structure" under the electron beam during microscopy imaging was observed, likely from coordination between alginate and [C mim][OAc]. Thus, this work has revealed the strong and unexpected effects of three different plasticizers on the hydrogen bonding and electrostatic interactions within chitosan/alginate polyelectrolyte complexed materials, which have potential for biomedical applications where balanced hydrophilicity and mechanical properties are required.
这项工作描述了不同增塑剂，即甘油、三醋精和1-乙基-3-甲基咪唑醋酸盐（[C mim][OAc]）对热机械加工的块状壳聚糖和壳聚糖/藻酸盐材料的结构和性能的影响。力学数据表明，对于壳聚糖基质，甘油和[C mim][OAc]在降低生物聚合物链之间的分子内和分子间作用力方面非常有效，导致延展性增加，而三醋精的增塑效果较小。尽管如此，这种三酯有效地抑制了生物聚合物的重结晶，而[C mim][OAc]则促进了重结晶。相比之下，对于壳聚糖/藻酸盐基质，加入三醋精会导致重结晶增加、热稳定性提高和优异的力学性能。三醋精有助于这种聚电解质复合体系中生物聚合物链之间的相互作用。相比之下，用[C mim][OAc]增塑的壳聚糖/藻酸盐材料表现出最明显的相分离、最差的力学性能和最高的表面亲水性，这种行为与聚电解质络合和生物聚合物链之间的氢键破坏有关。有趣的是，在显微镜成像过程中观察到电子束下形成了“新结构”，可能是藻酸盐和[C mim][OAc]之间的配位作用。因此，这项工作揭示了三种不同增塑剂对壳聚糖/藻酸盐聚电解质复合材料中氢键和静电相互作用的强烈且意想不到的影响，这些材料在需要平衡亲水性和力学性能的生物医学应用中具有潜力。
