| Hydrogel is a kind of high water absorption and retention material, is widely used in chemical, pharmaceutical and other industries. The preparation method of the hydrogel, reaction medium have direct effects on the performance and application of the product. Diels-Alder ?D-A? reaction has advantages of mild reaction condition, no small molecules generated, is expected to be applied to the in situ crosslinking hydrogels.This research prepared the water-soluble acrylamide copolymer containing diene groups and maleic anhydride esterification products containing dienes affinity groups, to prepare hydrogel in aqueous phase through D-A reaction.That is in situ crosslinking hydrogel. The performance of the hydrogel and de-crosslinking of the gel were studied.?1? Water-soluble diene polymer P?AM-FMA? was prepared through precipitation polymerization using acrylamide ?AM?, furfuryl methacrylate ?FMA? as the monomers.Water-soluble diene polymer P?NVP-FMA? was prepared using N-vinyl pyrrolidone and FMA as the monomers. The molecular weight and structure of product were characterized. The best mole ratio of AM:FMA was found to be 100:0.47-100:2.4 and NVP:FMA to be 100:4.0-100:10.?2? Water-soluble dienophile MA-DEA was synthesized through esterification reaction of maleic anhydride ?MA? and diethylene glycol ?DEA?, using anhydrous sodium acetate as catalyst. The effect of the reactant ratio and the dosage of catalyst on the esterification rate were studied. The best mole ratio of MA and DEA was found as 2.1:1, the best catalyst dosage was 1.0% based on the total mass of reactants.?3? The hydrogel was prepared thruogh in situ D-A reaction between diene polymer P?AM-FMA? and dienophile MA-DEA in water. The influence of temperature, ratio of reactants on gelation time, reaction rate were investigated through online viscometry. The kinetics of the gelation process was investigated and the the crosslinking activation energy was found to be 18.04-19.93 KJ·mol-1. Investigation was also performed to reveal the swelling property, salt resistance, compressive strength of the hydrogels obtained.?4? By crosslinking and decrosslinking behaviours it was found that orgainic compound such as N,N-Dimethylformamide ?DMF? in water phase influenced D-A reaction by increasing the activation energy while organic solvent ?DMF? could accelerate the retro-D-A reaction, leading to decrosslinking.The present work develops a novel in-situ crosslinking hydrogel based on catalyst-free Diels-Alder reaction. Such a hydrogel provides great potential for applications particularly in leaking stoppage and internal hemostasis. |
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