Enhanced Reflectance Wavelength Shift of PS-b-P2VP Films Using Reactive Monomer and Photo-Initiator

The reactive monomers (RM) draw much attention due to many possible applications on the liquid crystal alignment in LCD. A photo-initiator (2,2-Dimethoxy-2-phenylacetophenone (DMPA)) decomposes to free radicals when exposed to UV light. Poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP) lamellar film with alternating hydrophobic block-hydrophilic polyelectrolyte block polymers (52kg/mol-b-57kg/mol) were prepared for the photonic gel. The photophysical and photochemical effects of RM and DMPA to the PS-b-P2VP photonic gel film was studied. The reactive monomer added to the Photonic gel films increased the light scattering especially at blue region compared to the PS-b-P2VP photonic gel films. Irradiation of photonic gel containing RM and DMPA showed clear color. Swelling of films with ethanol (490 nm approximate to 500 nm) exhibited shorter wave length reflection compared with those swollen with DI water (581 nm approximate to 649 nm). This study showed that the water induced more hydrophobic and hydrophilic contrast compared to the Ethyl alcohol. The irradiation of photonic gel films with UV effectively controlled the reflecting color from red to blue (654 nm approximate to 508 nm), DMPA (705 nm approximate to 513 nm) and RM (637 nm approximate to 405 nm). RM and DMPA additive increased the clarity of the film and give feasibility for color control of photonic gel.