延时溶胀聚丙烯酰胺微球及其溶胀行为

The Delayed-swelling PAM Microsphere and Its Swelling Kinetics

利用丙烯酸二甲氨基乙酯和1,4-二溴丁烷的季铵化反应,合成了一种具有β位季铵结构的可水解交联剂（LC）。将LC单独使用,或和N,N-亚甲基双丙烯酰胺（Bis）联合使用,同时与丙烯酰胺（AM）和2-丙烯酰胺-2-甲基丙磺酸（AMPS）经反相细乳液聚合制得具有延时溶胀特性的交联聚丙烯酰胺（PAM）微球。DLS测试结果表明：微球粒径为300～500 nm,粒径分布窄。通过透光率变化表征了微球的溶胀动力学,结果表明：在中性和75℃下,LC水解速率比中性的丙烯酸酯交联剂快4倍左右,并且其水解速率随p H的降低而变慢,弱酸性条件可抑制LC水解,p H=8.9时,溶胀时间为2 d,p H=5.0时,溶胀时间延长至40 d。通过调节LC质量分数（2%～5%）、Bis质量分数（0～0.05%）、水质p H值（5.0～8.9）和温度（75～100℃）使微球溶胀时间在2～40 d范围内可调。

A new hydrolysable crosslinking agent LC with β-quaternary ammonium structure was synthesized by quaternization reaction of dimethylaminoethyl acrylate and 1,4-dibromobutane. By inverse miniemulsion polymerization,a series of cross- linked polyacrylamide（ PAM） microspheres with delayed-swelling characteristics were prepared,containing LC alone or LC and N,N-methylene bisacrylamide（ Bis）. The particle size of the microspheres was 300 ～ 500 nm,and the distribution was narrow. The delayed-swelling characteristics of crosslinked PAM microspheres can be dissected by light transmittance. The results showed that LC hydrolyzed four times faster than the current non-ionic acrylate cross-linker under neutral condition and 75 °C. The swelling time（ tS） was 2 d at p H = 8. 9,while tSwas increased to 40 d at p H = 5. 0. Its hydrolysis rate was decreased with the decrease of p H,and the weak acid condition can inhibit the hydrolysis of LC. The swelling time can be adjusted by the usages of LC（ 2% ～ 5%） and Bis（ 0 ～ 0. 05%）,the temperature（ 75 ～ 100 ℃） and p H（ 5. 0 ～ 8. 9）,and changed from 2 d to 40 d.