聚(N,N-二乙基丙烯酰胺-co-丙烯酸)共聚物的合成及表征

Synthesis and characterization of copolymer of poly(N,N-diethylacrylamide-co-acrylic acid)

分别以N,N-二乙基丙烯酰胺(DEA)和丙烯酸(AA)为温敏性和pH敏感性单体,AIBN为引发剂,四氢呋喃为溶剂,采用自由基聚合方法,制备单体组成比不同的系列无规共聚物P(DEA-co-AA).通过表征无规共聚物N元素质量分数,结合反应体系中单体的喂料比,得到了共聚时2种单体的竞聚率.对P(DEA-co-AA)进行苊烯标记,采用荧光光度仪,研究共聚物中不同单体比例对温敏性和pH敏感性的影响.结果表明:共聚时,AA反应活性比DEA反应活性大(r2/r1=1.371 5);随无规共聚物中AA比例增大,共聚物的最低临界溶解温度(LCST)升高,但相转变温度区间变宽,温敏性减弱,而pH敏感性增强;反之,单体DEA比例越大,LCST降低,但相转变温度区间变窄,温敏性增强,而pH敏感性减弱.

A series of random copolymers of P（DEA-co-AA） with various composition ratios of the mono- mers were prepared by means of free radical copolymerization when N, N-diethylacrylamide （DEA）, and acrylic acid （AA） were taken as temperature-sensitivity and pH-sensitivity monomers, azobisisobutyroni- trile （AIBN） as＇initiator, and tetrahydrofuran （THF） as solvent. The reactivity ratios of two monomers during copolymerization were obtained by means of characterization of N-element content in random copol- ymer and feed ratio of monomers in reaction system. Acenaphthylene tagging was carried out for the co- polymer of P（DEA-co-AA） and the influence of monomer feed ratio in copolymers on temperature-sensi- tivity and pH-sensitivity was investigated. The result showed that during the copolymerization, the reac- tion activity of AA would be higher than that of DEA（r2/r： ~ 1.3715） and with the increase of AA content ratio in random copolymer, the lowest critical solution temperature （LCST） would increase, hut the phase transition temperature range would become wider, temperature-sensitivity would be weakened, and pH- sensitivity strengthened. Whereas, with the increase of DEA, the LCST would decrease, but the phase transition temperature range would narrow, temperature-sensitivity strengthened, and pH-sensitivity weakened.