聚甲基丙烯酸/丙烯酰胺pH敏感凝胶的合成与溶胀行为研究

Synthesis of Novel pH-Sensitive Poly(methacrylic acid-co-acrylamide) Hydrogels and their Swelling Behavior

以单体丙烯酰胺(AM)、甲基丙烯酸(MAA),交联剂N-N′亚甲基双丙酰胺(BIS)为原料,通过自由基共聚合成了聚甲基丙烯酸/丙烯酰胺[P(MAA-co-AM)]水凝胶。研究了干凝胶在不同pH溶液中的溶胀动力学,结果表明不同AM、MAA单体配比的凝胶溶胀性具有很大差异,其溶胀率都随着溶液的pH增加而增大,在pH=12和pH=2溶液反复变换时显示可逆溶胀-退溶胀和快速响应特性,溶胀-退溶胀过程中搅拌作用对凝胶响应速率有显著影响。吸水平衡P(MAA-co-AM)水凝胶在酸性及碱性条件下均出现收缩,在pH=2下10min之内凝胶收缩90%以上,随着pH增大逐渐减慢。通过不同浓度的NaCl与CaCl2溶液研究了溶液离子强度以及反离子的电荷数对凝胶溶胀性影响,在NaCl溶液和水中,呈现反复溶胀-退溶胀响应特性。

A kind of novel hydrogels, poly（methacrylic acid-co-acrylamide）[poly（MAA-co-AM）], were prepared by radical aqueous copolymerization of acrylamide and methacrylic acid in the presence of crosslinker N-N＇-methylenebisacrylamide （BIS）. The swelling dynamics of the prepared dry hydrogels were investaged. The results show that the swelling behaviors of the prepared hydrogels are different with the different contents of methacrylic acid （MAA） in the hydrogels, and the swelling ratio of the hydrogels prepared increases with the increase of pH value of the solution. When the prepared hydrogels were shifted between solutions with pH=2 and pH=12, the hydrogels exhibit rapid reversible swelling-deswelling property, and their responsive rates are affected significantly by stirring. The hydrogels with absorbed water in equilibrium can be deswelled in both acid and alkaline solutions, they shrink more than 90% in solution of pH=2 within 10 min, and the shrinking rates decrease with the increase of pH value of the solution. The swelling properties of prepared hydrogels in NaCl and CaCl2 solutions were investigated; the results show that the influences of the ionic strength and the charge of counter ion in the solution are obvious, and that the hydrogels display the reversible swelling-deswelling property in water and NaCl solution.