单宁作为共引发剂和交联剂制备高伸长率水凝胶

以过硫酸铵为引发剂（APS）、杨梅综合单宁（TA）作为共引发剂和交联剂，通过自由基聚合制备了高伸长率水凝胶（TIC-gel）。通过红外光谱（FT-IR）、核磁共振（¹H-NMR）和浸泡尿素的方法研究了TA在TIC-gel中形成化学交联的机理。通过拉伸、压缩测试和流变学测试系统地分析了TIC-gel的力学性能和影响因素。结果表明：相比于传统化学交联水凝胶（PAM-MBA-gel），利用TA制备的凝胶具有高伸长率（2 250%）和高韧性（3.51 MJ/m³）。利用这一新的形成交联的方法所得的凝胶即使在高浓度时也能形成均匀的结构，可以很好地分散应力，为TIC-gel的高伸长率作出贡献。

Natural Products Condensed Tannins as both co-Initiator and Crosslinker to Prepare Highly Stretchable Polyacrylamide Hydrogel

Inspired by the function of condensed tannins(TA) in protecting tissue from the attack of free radicals,a simple and novel method was designed to prepare chemically crosslinked and highly tough hydrogels with homogeneous network with the presence of condensed tannins.During the process of polymerization,condensed tannins could capture free radicals from the initiator and become the starting point for the growth of polymer.By this way,condensed tannin could act as both co-initiator and crosslinking center to prepare highly stretchable hydrogels(TIC-gel) via radical polymerization.The mechanism that using TA to form crosslinking structure was put forward and confirmed by ¹H-NMR,FT-IR and immersing the TIC-gel in urea solution.The mechanical properties of TIC-gels were studied by a series of tensile measurements and rheological tests.As a result,these hydrogels could be stretched up to 2 250% with a maximal fracture energy 3.51 MJ/m³.This novel hydrogel has homogeneous network structure which is quite different from the heterogeneous network structure of conventional chemically crosslinked hydrogels(PAM-MBA-gel).Such good homogeneous network could effectively transfer the load among the network to endow the hydrogel with high elongation.