以聚氨酯预聚物为交联剂的两性水凝胶

为了改善水凝胶的强度,通过端丙烯酸酯基阴离子型聚氨酯(PU)与甲基丙烯酰氧乙基苄基二甲基氯化铵(MAEBDAC)的共聚交联,合成了系列两性水凝胶(简称L1—L5)。采用差式扫描量热法(DSC)分析了阴阳离子摩尔比为0.3/1(样品L1)、1/1(样品L3)和1.3/1(样品L5)的干凝胶,结果表明,两组分间相容性良好。处于等电点的样品L3中没有微孔结构,且其可冻结水含量仅为总溶胀水量的11.7％,而在样品L1和L5中均具有微孔结构且可冻结水含量增至50％。研究pH响应性表明,水凝胶的响应行为取决于凝胶中过量电荷的性质,外加电介质对样品L3的吸水能力影响较小。凝胶强度随聚氨酯链段的引入而提高。

Ampholytic hydrogels with polyurethane prepolymer as the crosslinking agent

The hydrogel strength of ampholytic hydrogels was improved by copolymerizing anionic acrylate polyurethane prepolymer (PU) with methacryloxyethyl benzyl dimethyl ammonium chloride (MAEBDAC) to prepare a series of ampholytic hydrogels defined as sample L1-L5. The differential scanning caiorimetry (DSC) curves of dried hydrogels sample L1, L3 and L5 with anion/cation molar ratios of 0. 3/3, 1/1 and 1. 3/1 had only one glass transition temperature, indicating only one phase. No pores were observed in the cross-section of dried hydrogel sample L3 with a freezable water content of 11.7% of the total water content. However, large numbers of pores were present in sample L1 and L5 with freezable water contents of about 50%. Moreover, the swelling properties depended on the nature of the net charge density within the hydrogels. Typical antipolyelectrolyte behavior in NaCl aqueous solution was noticed in sample L3. The hydrogel strength is improved with more PU chains in the hydrogel.