Yang Tiangang, Lu Shao-Hao, Zhu Honglin, Patetsos Antonios, McDonald Emma, Mellor Matthew D, Luo Yangchao, Rusling James F, Wang Xueju, He Jie
Department of Surgery and Neag Cancer Center, UConn Health, Farmington, Connecticut 06030, United States.
School of Chemistry, National University of Ireland at Galway, Galway H91 TK33, Ireland.
ACS Appl Mater Interfaces. 2024 Jul 31;16(30):40018-40029. doi: 10.1021/acsami.4c08592. Epub 2024 Jul 19.
Cellulose and its composites, despite being abundant and sustainable, are typically brittle with very low flexibility/stretchability. This study reports a solution processing method to prepare porous, amorphous, and elastic cellulose hydrogels and films. Native cellulose dissolved in a water-ZnCl mixture can form ionic gels through in situ polymerization of acrylic acid (AA) to poly(acrylic acid) (PAA). The addition of up to 30 vol % AA does not change the solubility of cellulose in the water-ZnCl mixture. After polymerization, the formation of interpenetrated networks, resulting from the chemical cross-linking of PAA and the ionic/coordination binding among cellulose/PAA and ZnCl, gives rise to strong, transparent, and ionically conductive hydrogels. These hydrogels can be used for wearable sensors to detect mechanical deformation under stretching, compression, and bending. Upon removal of ZnCl and drying the gels, semitransparent amorphous cellulose composite films can be obtained with a Young's modulus of up to 4 GPa. The rehydration of these films leads to the formation of tough, highly elastic composites. With a water content of 3-10.5%, cellulose-containing films as strong as paper also show typical characteristics of elastomers with an elongation of up to 1300%. Such composite films provide an alternative solution to resolving the material sustainability of natural polymers without compromising their mechanical properties.
纤维素及其复合材料虽然储量丰富且可持续，但通常很脆，柔韧性/拉伸性极低。本研究报告了一种溶液加工方法，用于制备多孔、无定形且具有弹性的纤维素水凝胶和薄膜。溶解在水 - 氯化锌混合物中的天然纤维素可通过丙烯酸（AA）原位聚合成聚丙烯酸（PAA）形成离子凝胶。添加高达30体积%的AA不会改变纤维素在水 - 氯化锌混合物中的溶解度。聚合后，PAA的化学交联以及纤维素/PAA与氯化锌之间的离子/配位键合导致互穿网络的形成，从而产生坚固、透明且具有离子导电性的水凝胶。这些水凝胶可用于可穿戴传感器，以检测拉伸、压缩和弯曲状态下的机械变形。去除氯化锌并干燥凝胶后，可获得杨氏模量高达4 GPa的半透明无定形纤维素复合薄膜。这些薄膜再水化会形成坚韧、高弹性的复合材料。含水量为3 - 10.5%时，强度与纸张相当的含纤维素薄膜还表现出典型的弹性体特性，伸长率高达1300%。这种复合薄膜为解决天然聚合物的材料可持续性问题提供了一种替代方案，同时又不损害其机械性能。
