pH快速响应PNIPAAm-co-PAAc水凝胶的制备及溶胀动力学

Preparation of Fast-Response pH-Sensitive PNIPAAm- co-PAAc Hydrogels and Their Swelling Kinetics

以硅胶微粒为致孔剂 ,制备了一系列多孔聚 (N 异丙基丙烯酰胺 /丙烯酸 ) (PNIPAAm co PAAc)无规共聚水凝胶。研究了各种单体配比的水凝胶在不同溶胀历史条件下的溶胀动力学。结果表明 ,多孔凝胶由于孔结构的存在 ,其平均溶胀速率相对于普通凝胶提高约 15 0倍 ,且溶胀历史对共聚水凝胶的平衡溶胀率无任何影响 ,但对它们的溶胀动力学影响很大。酸性溶胀历史的共聚水凝胶表现出S形溶胀曲线 ,为一、二级动力学的复合结果 ;

A series of porous PNIPAAm-co-PAAc hydrogels were synthesized by radical copolymerization of (N-isopropylacrylamide)(NIPAAm) and acrylic acid(AAc) using silica particles as a porogent. The dynamic swelling kinetics of the hydrogels pretreated in different buffer solutions have been studied. Experimental results revealed that the swelling rate of the porous hydrogels greatly increased in comparison with nonporous hydrogels due to their porous structure. And although the previous treatment did not affect the equilibrium swelling (degree) of (copolymer) hydrogels, a strong influence on their dynamic swelling kinetics was still observed (especially) for the copolymers with composition of NIPAAm between 30% and 70%(mole fraction). When subsequently soaked in a neutral (solution) with pH=7, these copolymer samples exhibited sigmoidal swelling curves by an autoacceleration mechanism. The dynamic swelling of the copolymer and homopolymer hydrogels at pH=7 after soaking in a solution of the same pH can be described by second-order kinetics.