Temperature and pH Dual-Responsive Shape-Transforming Block Copolymer Particles with Tunable Optical Property

We report a simple and robust strategy to prepare temperature/pH dual-responsive shape-switchable block copolymer (BCP) particles composed of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) and temperature/pH-responsive poly(N-(2-(diethylamino)ethyl)acrylamide-r-N-isopropylacrylamide) (poly(DEAEAM-r-NIPAM)) surfactants. The polymer surfactants were carefully designed to produce a dramatic change in relative solubility in response to subtle temperature and pH change near physiological condition (i.e. human body temperature and neutral pH). The shape transition of BCP particles from lens to football shape was occurred within very narrow temperature and pH range: no transition for pH 6.0, 40-50 °C for pH 6.5, and 25-35 °C for pH 7.0. Furthermore, the BCP particles showed reversible shape-transforming behavior in response to orthogonal temperature/pH changes. In addition, the incorporation of fluorescent dye-functionalized PS and P4VP into BCP particles allowed colorimetric monitoring of temperature and pH changes, which suggests a promising possibility of these particles in clinical and biomedical application.