Application of syndiotacticity-rich PVA hydrogels prepared at a low temperature to thermo- and pH-responsive release devices
Application of syndiotacticity-rich PVA hydrogels prepared at a low temperature to thermo- and pH-responsive release devices
复制标题
低温制备的富含间同立构规整度的PVA水凝胶在热响应和pH响应释放装置中的应用
DOI：
10.1002/1097-4628(20001003)78:1
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发表时间：
2000
影响因子：
3
通讯作者：
K. Yamaura
中科院分区：
文献类型：
--
作者：
S. Horiike;Kyouji Yumoto;K. Kanbara;S. Matsuzawa;K. Yamaura
使用pH 4.0、7.4和9.0的缓冲溶液(BS)在0℃下制备了三种物理交联的富含间同立构规整度的聚(乙烯醇)(s-PVA)水凝胶。三种凝胶在高于0℃的温度下浸入相同的BS中制备时，首先发生膨胀，然后在12小时后开始收缩。在 27、37 和 47°C 下研究了使用 pH 7.4 的 BS 制备的圆柱形凝胶中亮蓝 (3 mg/l mL) 的释放情况。亮蓝已几乎完全释放，花费了 4-12 小时。在27、37和47°C的温度下，从凝胶中的释放速率随着温度的升高而变大。亮蓝释放的主要因素不是凝胶的收缩，而是溶胀，因为在27、37和47℃下，溶胀度（DS）随着温度的升高而变大。由于在pH 4.0 的早期阶段水凝胶的DS 增加，因此从凝胶（pH 4.0）的释放速率大于凝胶（pH 7.4）的释放速率。由于释放过程中的膨胀，从前 60% 的释放分数评估，这些释放在 pH 7.4 下的表观扩散指数低于 0.45。由于立即膨胀，pH 4.0 时的指数为 0.45。在几种温度变化下观察到无规PVA（a-PVA）水凝胶收缩行为的开关。亮蓝在 5°C 下的释放速率低于 27°C 下的释放速率，并且在 5°C 下经过一个开关循环后没有观察到变化。
Three kinds of physically cross-linked syndiotacticity-rich poly(vinyl alcohol) (s-PVA) hydrogels were prepared at 0°C with use of the buffer solutions (BS) of pHs 4.0, 7.4, and 9.0. Three gels swelled at first and then began to shrink after 12 h when they were dipped in the same BS for preparation at higher temperature than 0°C. The release of Brilliant Blue (3 mg/l mL) from the cylindrical gels prepared using BS of pH 7.4 was studied at 27, 37, and 47°C. Brilliant Blue has been released spending 4-12 h almost completely. The rate of release from the gel at temperatures of 27, 37, and 47°C became large with increasing temperature. The main factor on release of Brilliant Blue is not the contraction of gel, but swelling, because the degree of swelling (DS) became large with increasing temperatures for 27, 37, and 47°C. The rate of release from the gel (pH 4.0) was larger than that (pH 7.4) due to the increased DS of the hydrogel in early step at pH of 4.0. The apparent diffusion exponents of these releases at pH 7.4 evaluated from first 60% of the fractional release were lower than 0.45 due to the swelling during release. The exponent at pH 4.0 was 0.45 due to immediate swelling. The on-off of shrinking behavior of atactic PVA (a-PVA) hydrogel was observed under several temperature changes. The rate of release of Brilliant Blue at 5°C was lower than that at 27°C and no change was observed at 5°C after one on-off cycle.