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首页> 外文期刊>Journal of Applied Polymer Science >Application of syndiotacticity-rich PVA hydrogels prepared at a low temperature to thermo- and pH-responsive release devices
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Application of syndiotacticity-rich PVA hydrogels prepared at a low temperature to thermo- and pH-responsive release devices

机译：低温制备的富含同立构规整度的PVA水凝胶在热响应和pH响应释放装置中的应用

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Three kinds of physically cross-linked syndiotacticity-rich poly(vinyl alcohol) (s-PVA) hydrogels were prepared at 0 degrees 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 degrees C. The release of Brilliant Blue (3 mg/l mt) from the cylindrical gels prepared using BS of pH 7.4 was studied at 27, 37, and 47 degrees 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 degrees 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 degrees 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 degrees C was lower than that at 27 degrees C and no change was observed at 5 degrees C after one on-off cycle. (C) 2000 John Wiley & Sons, Inc. [References: 18]
机译：使用pH值为4.0、7.4和9.0的缓冲溶液（BS）在0摄氏度下制备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。将三种凝胶先溶胀，然后将它们浸入同一BS中以在高于0摄氏度的高温下制备，然后在12小时后开始收缩。使用BS制备的圆柱状凝胶释放出亮蓝（3 mg / l mt）在27、37和47摄氏度下研究了7.4的pH值。艳蓝几乎在4至12小时内被释放出来。随着温度的升高，在27、37和47摄氏度的温度下从凝胶中释放的速率变大。亮蓝释放的主要因素不是凝胶的收缩，而是溶胀，因为溶胀度（DS）随着温度在27、37和47摄氏度的升高而变大。从凝胶中释放的速率（pH 4.0）大于（pH 7.4），这是因为水凝胶在pH为4.0的早期步骤中的DS增加。从释放的最初60％开始，在pH 7.4下评估的这些释放的表观扩散指数低于0.45，这是由于释放过程中的溶胀。由于立即溶胀，pH 4.0的指数为0.45。在几个温度变化下观察到无规PVA（a-PVA）水凝胶的收缩行为的开-关。在一个开-关循环后，在5摄氏度下的艳蓝释放速率低于27摄氏度下的释放速率，并且在5摄氏度下没有观察到变化。 （C）2000 John Wiley＆Sons，Inc. [参考：18]

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