“…Various zwitterionic betaine gels, such as phosphobetaine [1e3], sulfobetaine [4e6], carboxybetaine [7,8], semiinterpenetrating network (IPN) gel composed of amphiphilic gel and zwitterionic betaine polymers [9,10], and chemicalephysical cross-linked double network (DN) gel, which was obtained by introducing ductile physical networks into the network of chemically cross-linked polysulfobetaine gels [11], have shown excellent chemical stability [12], good biocompatibility [13], ultralow fouling [14,15], and excellent mechanical properties [14,16]. Studies on the properties of polymers or gels based on betaine have received significant attention in the scientific community.…”