Fluorescence study on the swelling behavior of comb-type grafted poly(N-isopropylacrylamide) hydrogels
Fluorescence study on the swelling behavior of comb-type grafted poly(N-isopropylacrylamide) hydrogels
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DOI：
10.1021/ma020683y
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发表时间：
2002-10-08
期刊：
影响因子：
5.5
通讯作者：
Okano, T
中科院分区：
文献类型：
--
作者：
Annaka, M;Tanaka, C;Okano, T
研究了梳型接枝聚n -异丙基丙烯酰胺凝胶在体积转变温度上的温度跳变收缩机理。用丹酚探针标记接枝链或凝胶网络，并用荧光光谱法研究了丹酚标记凝胶在微环境中的时间变化。梳子型接枝聚n -异丙基丙烯酰胺凝胶相对于普通型NIPA凝胶表现出快速的收缩，并且通过观察丹酚基团最大发射波长λ (cm)的时间变化发现其微环境的变化比普通型聚n -异丙基丙烯酰胺凝胶的疏水速度快10倍以上。接枝链的自由移动特性表明，随着温度的升高，接枝链迅速脱水，形成紧密堆积的球状物，随后脱水的接枝链发生疏水分子间聚集。脱水接枝链形成疏水核，增强了网络的疏水聚集。
The shrinking mechanism of comb-type grafted poly(N-isopropylacrylamide) gel due to temperature jump across its volume transition temperature has been investigated. Grafted chains or gel networks were labeled by a dansyl probe, and the temporal change in micro environment of the dansyl-labeled gel was investigated by means of fluorescence spectroscopy. The comb-type grafted poly(N-isopropylacrylamide) gel exhibited a rapid shrinking compared to normal-type NIPA gel, and the change in its microenvironment was found to become hydrophobic more than 10 times faster than normal-type poly(N-isopropylacrylamide) gel by observation of temporal change in the maximum emission wavelength, lambda(cm), of the dansyl group. The freely mobile characteristics of grafted chains are expected to show the rapid dehydration to make tightly packed globules with temperature, followed by the subsequent hydrophobic intermolecular aggregation of dehydrated graft chains. The dehydrated grafted chains created the hydrophobic cores, which enhance the hydrophobic aggregation of the networks.