THERMAL-ANALYSIS OF THE VOLUME PHASE-TRANSITION WITH N-ISOPROPYLACRYLAMIDE GELS
THERMAL-ANALYSIS OF THE VOLUME PHASE-TRANSITION WITH N-ISOPROPYLACRYLAMIDE GELS
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DOI：
10.1021/ma00203a049
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发表时间：
1990-01-08
期刊：
影响因子：
5.5
通讯作者：
SAITO, S
中科院分区：
文献类型：
--
作者：
OTAKE, K;INOMATA, H;SAITO, S
研究了N-异丙基丙烯酰胺（NIPA）凝胶在水溶液中的热收缩型体积相变。实验主要包括用差示扫描量热仪（DSC）对NIPA凝胶和线性NIPA聚合物（PNIPA）与聚乙烯基甲基醚（PVME）的水溶液进行热分析，其凝胶为热收缩型。从DSC分析得到的NIPA凝胶的转变温度与通常从标准溶胀实验得到的那些进行了比较。该比较阐明了DSC用于测定转变温度的效率。对于线性聚合物溶液，从DSC得到的转变温度是令人满意的一致，其浊点。的转变温度和热的崩溃的NIPA凝胶表现出类似的值的PNIPA解决方案，这允许的推断，体积相变主要是由相同的因素控制的线性聚合物的线圈-球转变。凝胶的崩解转变热是吸热的，其绝对值大于非极性有机溶液体系的临界值。用线性聚合物溶液获得了类似的结果。用疏水相互作用的概念解释了实验结果。低分子量物质的加入改变了转变温度。这可以通过粘度B系数来解释。
Experimental work was done to study the thermoshrinking-type volume phase transition of N-isopropylacrylamide (NIPA) gel in aqueous solutions. The experiments principally consisted of the application of thermal analysis with a differential scanning calorimeter (DSC) to NIPA gels and to aqueous solutions of linear NIPA polymer (PNIPA) and poly (vinyl methyl ether)(PVME), whose gel is character-istic of the thermoshrinking type. The transition temperatures of NIPA gel obtained from DSC analysis were compared with those usually obtained from standard swelling experiments. This comparison clarified the efficiency of DSC for the determination of the transition temperature. For the linear polymer solutions, the transition temperatures obtained from DSC were satisfactorily consistent with their cloud points. Both the transition temperature and heat of the collapse of the NIPA gel showed similar values to those of the PNIPA solutions, which permitted the inference that the volume phase transition is controlled primarily by the same factors as the coil-globule transition of the linear polymer. The transition heat of collapse of the gel was endothermic and its absolute value was larger than those reported for nonpolar organic solution systems. Similar results were obtained with the linear polymer solutions. The experimen-tal results were interpreted byusing the concept of hydrophobic interaction. The addition of low molecu-lar weightsubstances changed the transition temperature. This can be explained through the viscosity B coefficient.