Self-healing And Shape-memory Hydrogels Based On Supramolecular Interaction

Supramolecular materials are constructed by non-covalent bond interaction among the molecular chains.Compared with traditional chemical covalent materials,supramolecular materials show much interesting and valuable properties resulting from their dynamic nature,such as self-healing,stimuli-responsiveness and adaptability.Hydrogels have an extensive potential prospect in biomedical,industry,agriculture some fields,due to the three-dimensional network structure with high water content.The performance conventional covalent hydrogels have great limitation,like weak mechanical property,unrepairable,unresponsiveness and so on.In contrast,supramolecular hydrogels based on dynamic non-covalent network has a great promote not only in mechanical property,but also in multi-functionalization.In this thesis,the tough and multi-functional supramolecular hydrogels based on host-guest interaction,metal coordination,hydrogen bond and hydrophobic interaction are realized.The main research and results are summarized as follows:1.We design a new way to prepare supramolecular hydrogels by using PCD as the polyfunctional crosslinking agent to replace the traditional monofunctional CD molecules grafted on the polymer chains to improve the self-healing property.The hydrogel is synthesized via in-situ copolymerization of the adamantane-containing monomer N-adamantylacrylamide(Ad-AAm)and monomer acrylic acid(AAc)in the PCD aqueous solution.These hydrogels exhibit high self-healing percentage and excellent shape memory behavior based on the rapid recoverable inclusion complexation of PCD and Ad groups2.We integrate the LMP chains into a physical PAAm network crosslinked between PCD and Ad units to construct a hybrid hydrogel(LMP-PCD/Ad hybrid hydrogel),and then apply a soaking strategy to convert the hybrid hydrogel into highly tough DN hydrogels via the formation of the LMP network.As a result,the obtained LMP-PCD/Ad DN hydrogels display excellent mechanical strength and toughness,comparable to the week and brittle conventional chemical hydrogels.DN hydrogels also demonstrate a rapid self-recovery property,remarkable dual responsive shape-memory property,and notable self-healing property.3.Physical PA6ACA hydrogels are obtained via in-situ free radical polymerization of monomers.We endow the hydrogels with both adhesion and self-healing property.In a low pH conditions,-COO~-is converted to-COOH,which reduces the solubility of the PA6ACA chains,and the hydrophobic aggregation of the alkane chains occurs,and the gels shrink.The obtained hydrophobic aggregates gel has good toughness.Combining the PA6ACA hydrogels and PNIPAM hydrogels of clay crosslinking,the double-layers hydrogels can be used as a dual responsive gel actuator.