阴离子聚丙烯酰胺微球降解规律

Degradation of Anionic Polyacrylamide Microsphere

李晓丹 李光辉 严美容 周伟康

LI Xiaodan，LI Guanghui，YAN Meirong，ZHOU Weikang

为揭示阴离子聚丙烯酰胺微球的降解规律，以2-丙烯酰胺-2甲基丙磺酸（AMPS）与丙烯酰胺（AM）为单体，采用乳液聚合法制备了阴离子聚丙烯酰胺P（AM-AMPS）微球。通过透射电镜、红外光谱仪、热重分析仪分析了所制备微球的结构与热稳定性，并测量了在水中溶胀后的微球在80℃下降解不同时间的黏度、pH值和粒径。结果表明，合成的P（AM-AMPS）微球分布均匀，粒径约为70 nm，其与线性聚丙烯酰胺在无水条件下的热稳定性相近。与线性聚丙烯酰胺水解后呈碱性且pH值缓慢上升不同，微球在溶液中降解的0~4 h内，自由基氧化降解使微球溶液黏度急剧下降，而水解反应相对缓慢，pH值维持在2.75左右；4 h后，自由基氧化降解速率减小，水解反应促使溶液pH值迅速上升。在降解反应的0~4 h内，微球外层的阴离子聚合物链段首先降解，而后微球内核部分破碎，微球粒径迅速降低。

In order to reveal the degradation of anionic polyacrylamide microsphere，anionic polyacrylamide P（AM-AMPS）microsphere was prepared by emulsion polymerization using 2-acrylamide-2-methylpropanesulfonic acid（AMPS）and acrylamide （AM）as monomers. The structure and thermal stability of the prepared microsphere were analyzed by transmission electron microscopy，infrared spectrometer and thermogravimetric analyzer. The viscosity，pH value and particle size of the microsphere which degraded different times at 80℃ after swelling in water were measured. The results showed that the synthesized P （AM-AMPS）microsphere had a uniform distribution with a particle size of about 70 nm，whose thermal stability was similar to that of linear polyacrylamide under anhydrous condition. Different from the linear polyacrylamide hydrolysis，whose hydrolysate was alkaline and the pH value slowly increased，the oxidative degradation of free radical caused the viscosity of the microsphere solution to drop sharply during 0—4 h microsphere degradation in solution，while the hydrolysis reaction was relatively slow，and the pH value maintained at about 2.75. After 4 h，the oxidation degradation rate of free radical decreased，and the hydrolysis reaction promoted the pH value of solution to rise rapidly. Within 0—4 h of the degradation reaction，the anionic polymer segment in outer layer of the microsphere degraded first，and then the microsphere core partially broken，and the particle size of the microsphere rapidly decreased.

10.19346/j.cnki.1000-4092.2019.03.006