活性炭复合改善聚丙烯酸凝胶耐盐性及其溶胀机理

在活性炭(Ac)存在的情况下通过自由基溶液聚合，以过硫酸铵为引发剂，N,N′-亚甲基双丙烯酰胺为交联剂，制备了活性炭复合聚丙烯酸凝胶(PAA/AC)。 考察了凝胶在蒸馏水、生理盐水和不同pH值缓冲溶液中的平衡溶胀比以及溶胀动力学，结果表明，活性炭能有效提高凝胶的平衡溶胀比，在实验设计的pH值范围内复合凝胶具有比PAA凝胶更高的平衡溶胀比，蒸馏水和生理盐水中PAA/AC凝胶的平衡溶胀比分别可达到303和60 g/g，约为PAA凝胶的2.4倍。 讨论了凝胶的溶胀机理，结果表明，活性炭成分的介入破坏了聚合物链段之间的聚集态结构，减弱了聚合物链段之间的相互作用，提高了凝胶的溶胀能力。 示差扫描量热仪测定复合前后凝胶的玻璃化转变温度，扫描电子显微镜观察了复合前后凝胶的断面网络结构，结果进一步表明活性炭复合后聚合物链段之间的作用力减弱。

Salt Resistance Improvement of Polyacrylic Acid Gel by Activated Carbon Complex and Study on Its Swelling Mechanism

Polyacrylic acid/activated carbon composite hydrogel(PAA/AC) was prepared by free radical solution polymerization of acrylic acid(AA) using ammonium persulfate as an initiator and N,N′-methylene-bis-acrylamide as a crosslinker in the presence of activated carbon. The equilibrium swelling degree and the dynamics of the gels swelling in distilled water, saline and buffer solutions with different pH were studied. The results showed that the activated carbon enhanced the swelling capacity of PAA gel effectively, the PAA/AC hydrogel exhibits higher equilibrium degree of swelling(SWeq) than PAA hydrogel over the range of pH investigated, and the SWeq of PAA/AC is about 303 and 60(g/g) in distilled water and saline, respectively, which is about 2.4 times higher than that of PAA hydrogel. The mechanism of the swelling was also discussed, and the results showed that the aggregated structure of the polymer chains might be destroyed by the intervention of the activated carbon, which caused a decrease in interactions among polymer chains and an increase in the swelling capacity of PAA/AC gel. The glass transition temperatures(Tg) and cross sectional morphologies of PAA and PAA/AC gels were measured by differential scanning calorimetry(DSC) and scanning electron microscope(SEM), respectively, and the results further proved a decrease in the interactions among polymer chains.