Photo-responsive polymeric structures based on spiropyran

Abstract

Spiropyrans are one of the most popular classes of photocromic compounds as they are particularly interesting targets for the development of new multifunctional materials that take advantage of their photo-reversible interconversion between two thermodynamically stable states: a spiropyran (SP) form, and a merocyanine (MC) form, which have dramatically different charge, polarity and molecular conformations. In this work, polymer brushes based on spiropyran were synthesised on the interior of micro-capillaries to study the influence of these brushes on solvent flow through a confined space and to determine their sensing capabilities. We demonstrate that using “grafting from” approach we obtain a 3D arrangement of polymer brushes covalently attach to the inner wall of the micro-capillary where the spiropyran moiety has the freedom to open and close in response to light (ultraviolet, white light). This type of manipulation of capillary surface properties using light as the controlled external stimulus holds promise as a means for developing new modes of controlling liquid transport in micro-fluidic devices as well as novel micro-fluidic integrated optical sensors.