快速响应聚(N-异丙基丙烯酰胺)水凝胶的制备及性能

Synthesis and Properties of Poly(N-isopropylacrylamide) Hydrogels with Fast Response Rate

以N-异丙基丙烯酰胺为单体、N,N′-亚甲基双丙烯酰胺为交联剂、过硫酸铵为引发剂、N,N,N,′N′-四甲基乙二胺为加速剂,在不同浓度的羧甲基纤维素的水溶液中,在低温下聚合/交联制备了一系列快速响应的温度敏感性聚(N-异丙基丙烯酰胺)水凝胶。用SEM观察了其表面形态,测定了不同温度下达到平衡时水凝胶的溶胀比,研究了水凝胶的去溶胀动力学。结果表明,与传统水凝胶相比,该水凝胶的溶胀性能有所提高,并且对温度的变化具有较快的响应速率。以质量分数为0.75%的羧甲基纤维素水溶液中制备的水凝胶为例,该水凝胶在20℃时的溶胀比为21.4,而传统水凝胶在相同温度时的溶胀比仅为12.9;该水凝胶在1 m in内失去60%的水,在4 m in内失去约80%的水,而传统水凝胶在15 m in内仅失去66%左右的水。

Thermo-sensitive poly （N-isopropylacrylamide） （PNIPA） hydrogels with fast response rate were prepared in aqueous carboxymethylcellulose solutions with different concentrations by using N- isopropylacrylamide as monomer,N,N＇-methylenebisacrylamide as crosslinker,ammonium persulfate as initiator and N,N,N＇,N＇-tetramethylethylenediamine as accelerator. The surface morphology of PNIPA hydrogels were observed using a scanning electron microscope. The swelling ratios of the hydrogels at different temperatures were measured. Furthermore, the deswelling kinetics of the hydrogels was also studied through measuring their water retention. The result indicates that in comparision with a conventional PNIPA hydrogel prepared in water, the hydrogels prepared in aqueous carboxymethylcellulose solutions had higher swelling ratios at temperatures below the lower critical solution temperature and exhibited much faster response rate to temperature changes. Taking the hydrogel prepared in aqueous carboxymethylcellulose solution with weight percentage of 0.75% as an example, the swelling ratio of the hydrogel was 21.4 at 20 ℃, whereas the swelling ratio of the conventional hydrogel was 12.9 at the same temperature;the hydrogel lost 60% water within 1 min,andabout 80% water in 4 min,whereas the conventional hydrogel lost only about 66% water in 15 min.