Abstract
Polyampholyte gels,which have hierarchical structures,exhibit excellent self-healing properties and have great promise for biomateri-als and bioengineering.We investigated the relationship between microscopic structures and macroscopic viscoelastic properties of polyam-pholyte gels and found three factors influencing their viscoelastic properties,including the chemical crosslinking bonds,topological entangle-ments controlled by monomer concentration,and the ionic bonds.Ionic strength plays a major role on the strength of ionic bonds.A crossover point of elastic modulus and loss modulus was observed in the dynamic frequency sweeps at low monomer concentration or low chemical crosslinking density for gels with intermediate strength of ionic bonds.The solid-liquid transition signaled by the crossover point is a typical fea-ture of dynamic associated gels,representing the dynamical association-dissociation of the ionic bonds and full relaxation of the topological en-tanglements in the gel network.While the crossover point disappears when the ionic bonds are too weak or too strong to form"permanent"bonds.Consistently,in the non-linear yielding measurement,gels with intermediate strength of the ionic bonds are ductile and yield at very large shear strain due to the self-healing properties and the dynamic association-dissociation of the ionic bonds.But the self-healing properties disap-pear when the ionic bond strength is too weak or too strong.Our work reveals the mechanism of how the dynamic association-dissociation of ionic bonds influences both the linear and non-linear viscoelastic properties of the polyampholyte gels.
基金项目
National Natural Science Foundation of China(22273114)
National Key R&D Program of China(2023YFE0124500)
National Key R&D Program of China(2023YFC2411203)
International Partnership Program of the Chinese Academy of Sciences(027GJHZ2022061FN)
维普
万方数据