Institute of Chemistry, University of Campinas, P.O. Box 6154, 13083-970 Campinas, SP, Brazil.
Carbohydr Polym. 2013 Apr 15;94(1):317-22. doi: 10.1016/j.carbpol.2012.12.061. Epub 2013 Jan 3.
Regioselective sucrose 1'-O-methacrylate obtained by transesterification catalyzed by Proteinase-N was copolymerized with hydrophilic N-isopropylacrylamide and hydrophobic methyl methacrylate in different molar ratios by free radical polymerization. The copolymers were characterized by (13)C nuclear magnetic resonance spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetry. Solubility and phase behavior of aqueous solutions were also investigated. The glass transition of the copolymers presents a positive deviation from the values of the homopolymers due to the high density of inter and intramolecular hydrogen bonding. Their solubility is strongly dependent on the composition. Copolymers poor in methyl methacrylate are water soluble, while copolymers richer in methyl methacrylate behaves as hydrogel. These hydrogels are not chemically crosslinked and their form can be design prior swelling by the conventional processing methods, such as solvent casting and extrusion for instance. Copolymers of N-isopropylacrylamide are water soluble and their aqueous solutions present a lower critical solution temperature behavior forming thermoreversible hydrogels.
通过蛋白酶 N 催化的酯交换反应获得的区域选择性蔗糖 1'-O-甲基丙烯酰酯与亲水性 N-异丙基丙烯酰胺和疏水性甲基丙烯酸甲酯以不同摩尔比通过自由基聚合共聚。共聚物通过(13)C 核磁共振光谱、凝胶渗透色谱、差示扫描量热法和热重分析进行了表征。还研究了水溶液的溶解度和相行为。由于分子间和分子内氢键的高密度,共聚物的玻璃化转变呈现出与均聚物值的正偏差。它们的溶解度强烈依赖于组成。甲基丙烯酸甲酯含量低的共聚物可溶于水,而甲基丙烯酸甲酯含量高的共聚物则表现为水凝胶。这些水凝胶不是化学交联的,其形状可以通过常规的加工方法(例如溶剂浇铸和挤出)预先溶胀来设计。N-异丙基丙烯酰胺的共聚物可溶于水,其水溶液具有较低的临界溶液温度行为,形成热可逆水凝胶。