含丙胺酸之pH-敏感型水膠的吸水特性研究Investigation of Swelling Properties of a pH-Sensitive Hydrogel Containing Alanine Groups

摘 要

本文先以丙胺酸反應縮水甘油甲基丙烯酸酯而得到側鏈含有丙胺酸的親水性乙烯系單體(簡稱GAL)，接著混合GAL與聚乙二醇二丙烯酸酯，經聚合反應而得到簡稱為PGAH的水膠，再探討不同時間、溫度、不同類型的鹽類與不同pH值下的PGAH之吸水特性。而實驗結果顯示PGAH在50分鐘可吸水達本身重量的67倍；在5到55^oC之間，PGAH的吸水倍率受溫度的影響甚小。在鹽溶液中，陽離子為Li⁺、Na⁺、K⁺ 時，吸水倍率雖然是Li⁺ > Na⁺ > K⁺，但相差不大：而Na⁺、Mg²⁺、Al³⁺ 的溶液中，吸水倍率依序為Na⁺ > Mg²⁺ > Al³⁺。至於在pH 10～9的水溶液中，PGAH的吸水倍率維持在最高值，而隨著pH值的下降，其吸水倍率亦逐漸降到pH 2的最低值。因此，PGAH屬於pH-敏感型的水膠。

關鍵詞：水膠、丙胺酸、吸水倍率、pH-敏感型

Abstract

A hydrophilic vinyl monomer, glycidyl methacrylate (GMA)–alanine (ALA), was formed by the reaction between GMA and ALA. Then a hydrogel, PGAH, was prepared via a polymerization of glycidyl methacrylate–alanine with poly(ethylene glycol) diacrylate. The water absorbency for PGAH in deionized water tended toward equilibrium at 50 min and the swelling ratio was 67 g H₂O/(g PGAH). Within 5-55^oC, the water temperature affected the swelling ratio slightly. In saline solutions, the swelling ratios followed the order of Li⁺ > Na⁺ > K⁺ but their differences were not large. However, the swelling ratio of PGAH in Na⁺, Mg²⁺ and Al³⁺ solutions were ordered: Na⁺ > Mg²⁺ > Al³⁺. The swelling ratio of PGAH mantained a maximum value in pH 10-9, decreased with decreasing the solution pH and reached a minimum value at pH 2. That is, PGAH is a pH-sensitive hydrogel.    

Keywords: Hydrogel, Alanine, Swelling Ratio, pH-Sensitive