Development of composite membrane of crystalline polymers

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One of the important feature of preparing the composite film, growth mechanism of poly(2-vinyl pyridine) crystal was eluscidated. Precipitation behavior was examined by using various combinations of n-alcohols and hydrocarbons as the mixed solvent. The clouding temperature of polymer solution was examinedas a function of concentration of 1-octanol in the 0.03% P2VP solution in the mixture of 1-octanol and decalin. In higher concentration of 1-octanol in the solvent clouding temperature became higher. Measurement using other combination of alcohol and hydrocarbon for crystallizing solvents resulted in same relationship between clouding temperature and alcohol concentration in the solvent. The results show that the polymer concentration become lower, clouding temperature decrease. This relationship between polymer concentration and clouding temperature indicated that this system showed lower critical solution temperature (LCST) behavior. And this relationship also indicated that this phase separation was not liquid-liquid phase separation but solid-liquid phase separation. This solid-liquid phase separation corresponds to the fact that the morphology of the solution-grown crystal was not spherical shape but platelet. Disturbance of the interface is left for the problem to be solved for preparation of the composite film of two crystalline polymers,