Effect of different ionic liquids acting as plasticizers on the multi-scale structures and physical properties of hydroxypropyl methylcellulose/monosodium phosphate photophobic film

Abstract

Different ionic liquid (IL)s were added to hydroxypropyl methylcellulose /monosodium phosphate (HPMC/MSP) photophobic film to improve its ductility, and their effects on its multi-scale structures and physical properties were studied. After adding these ILs, smoothness of the fractal structure, tensile strength, modulus of the film did not change obviously, while the crystallinity, the number of holes, and elongation increased, the hole size and T_g decreased. Compared to films with other ILs, the film with 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF₄) showed the largest elongation and crystallinity, the smallest hole size, the least holes, and highest whiteness. The film with 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) showed the largest water content and the lowest T_g. The increased elongation proved that all these ILs could improve the ductility of the film, among which, [EMIM]BF₄ had the strongest plasticizing effect.

Keywords: Ductility; Ionic liquid; Photophobic film.