Photo-controlled fabrication of self-organized structures in honeycomb-patterned thin films with light-sensitive amphiphilic copolymer

The structures of honeycomb-patterned thin polymer films fabricated by casting polystyrene solution under humid conditions were controlled by illumination of ultraviolet (UV) light by the assistance of an added light-sensitive amphiphilic copolymer (Als) in the casting solution. Als was synthesized through the radical copolymerization of ruthenium(4-vinyl-4′-methyl-2,2′-bipyridine)bis(2,2′-bipyridine)bis(hexaflurophosphate) with N-vinylcarbazole. The synthesized Als was characterized using spectroscopic methods and a thermogravimetric analyzer. An appropriate duration of light illumination in a suitable concentration of Als minimized the irregularity of the honeycomb pattern. However, irregular patterns were induced by an excessive amount of Als or by excessive illumination time.