Inoue Tohru, Yamashita Kohei
Department of Chemistry, Faculty of Science, Fukuoka University, Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan.
J Colloid Interface Sci. 2006 Aug 15;300(2):774-81. doi: 10.1016/j.jcis.2006.04.025. Epub 2006 May 11.
The aggregation behavior of polypropylene oxide (PPO) with positive charges at both ends was investigated in aqueous solution by means of the measurements of solution turbidity, dynamic light-scattering, differential scanning calorimetry, and dye solubilization. The positive charges were produced by protonation of terminal NH(2) groups attached to the polymer composed of 33 PO units. It was found that the aggregation behavior is quite sensitive to temperature. At low temperature, the polymer dissolves in water as a unimer. When temperature is increased, the unimer solution undergoes a phase separation to give a turbid solution. Further increase in temperature produces a transparent micellar solution. The aggregation of the polymer molecules must be induced by the dehydration of PPO chain caused by temperature increase. According to the analysis of heat absorptions associated with the melting of the solid mixture and the phase separation of the unimer solution, it is suggested that approximately 10% dehydration of PPO chain causes the phase separation. The temperature-composition phase diagram of aqueous mixture of this polymer was constructed on the basis of turbidity and DSC experiments, which reveals the aggregation behavior of this polymer in aqueous medium as a function of concentration and temperature.
通过测量溶液浊度、动态光散射、差示扫描量热法和染料增溶作用，研究了两端带正电荷的聚环氧丙烷（PPO）在水溶液中的聚集行为。正电荷是由连接在由33个环氧丙烷单元组成的聚合物上的末端NH₂基团质子化产生的。发现聚集行为对温度相当敏感。在低温下，聚合物以单分子形式溶解于水中。当温度升高时，单分子溶液发生相分离，形成浑浊溶液。进一步升高温度会产生透明的胶束溶液。聚合物分子的聚集必定是由温度升高导致的PPO链脱水所引起的。根据对与固体混合物熔化和单分子溶液相分离相关的热吸收分析，表明PPO链约10%的脱水会导致相分离。基于浊度和差示扫描量热法实验构建了该聚合物水混合物的温度-组成相图，其揭示了该聚合物在水介质中的聚集行为随浓度和温度的变化情况。
