通过RAFT聚合方法合成具有高强度和高溶胀率的纳米水凝胶

为了得到具有高强度和高溶胀率的纳米水凝胶(NCgels),N-异丙基丙烯酰胺通过可逆加成断裂链转移(RAFT)聚合的方法,插层在含有质量分数为0.25%～15%的可扩展的有机化的蒙脱土(Clay-S)层间并交联。结果表明,与传统水凝胶相比,该水凝胶的强度和溶胀性能得到了很大提高,并且对温度的变化具有较快的响应速率。以质量分数为5%的蒙脱土,链转移剂的质量分数为0.5%制备的纳米水凝胶为例,该水凝胶在20℃的溶胀率为450,而传统水凝胶在相同温度时的溶胀率仅为20;该水凝胶在1min内失去75%的水,在4min内失去约90%的水,而传统水凝胶在15min内仅失去66%左右的水。

Nanocomposite Hydrogels with High Mechanical Strength and High Swelling Ratio by RAFT Polymerization

Nanocomposite hydrogels(NC gels)was prepared based on poly(N-isopropylacrylamide)(PNIPAM)containing 0.25%～15% of the expandable synthetic hectorite Laponite XLS(Clay-S)by reversible addition fragmentation chain transfer(RAFT)polymerization.The swelling behaviors were investigated and the hydrogels by RAFT polymerization(RAFT gels)show accelerated shrinking kinetics and higher swelling ratio compared with conventional hydrogel(CGel).It could be attributed to the presence of dangling chains mainly caused by chain transfer agent(CTA),which could retard the crosslinking reaction rate greatly.Taking hydrogel prepared with 5% clay and 0.5% CTA as an example,the swelling ratio of the hydrogel was 450 at 20 ℃,whereas that of conventional hydrogel was 20 at the same temperature;the hydrogel lost 75% water within 1 min and about 90% water within 4 mins,whereas conventional hydrogel lost only about 66% water within 15 mins.