The effects of 60 organic solvent on poly(lactic acid) (PLA) were systematically investigated using the Hansen solubility parameter (HSP). The hydrogen bonding solubility parameter accurately reflects the solubility of PLA films using HSP but it depends on hydrogen bonding, as well as dispersion and polar parameters. The PLA films immersed in organic solvent became cloudy and showed no changes in chemical structure. However, solvent‐induced crystallization of the PLA films was observed. Crystalline structures do not dependent on the organic solvent but on the degree of swelling. The organic solvent‐induced crystallization formed a crystallized mixture of a‐ and β‐forms. The density of the crystalline PLA films was lower than that of amorphous PLA films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The photo reactivity and photo alignment sensitivity of a fluorine-containing aromatic polyimide, 4,4-(hexafluoroisopropylidene) diphthalic anhydride 2,3,5,6-tetramethyl-1,4-pheny lene diamine (6FDA-TeMPD), were systematically investigated. This polyimide has high heat resistance, high solubility in polar solvents, high optical transparency, and low refractive index. Different molecular ordering structures of 6FDA-TeMPD polyimide were obtained by controlling the type of casting solvent as well as the dry conditions. The photo reactivity of the polyimide obtained under highly volatile preparation conditions is higher than that obtained under lowly volatile conditions. The photo reactivity showed higher dependency on the type of casting solvent than on the heat treatment temperature. The fluorescence spectra show that the polymer condensation increased under 254 nm linearly polarized ultraviolet irradiation. On the other hand, the photo alignment sensitivity did not depend on the polymer cohesiveness, but rather on the residual solvent trace in the polyimide film. Moreover, the photo alignment sensitivity can be increased by reducing the amount of residual solvent in the polymer film.