Shape and Color Switchable Block Copolymer Particles by Temperature and pH Dual Responses

Abstract

Herein, we report a simple and robust strategy for preparing dual-responsive shape-switchable block copolymer (BCP) particles, which respond to subtle temperature and pH changes near physiological conditions (i.e., human body temperature and neutral pH). The shape transition of polystyrene-b-poly(4-vinylpyridine) BCP particles between lens and football shapes occurs in very narrow temperature and pH ranges: no temperature-based transition for pH 6.0, 40-50 degrees C transition for pH 6.5, and 25-35 degrees C for pH 7.0. To achieve these shape transitions, temperature/pH-responsive polymer surfactants of p oly (N-(2-(diethylamino)ethyl)acrylamide-r-N-isopropylacrylamide) are designed to induce dramatic changes in relative solubility and their location in response to temperature and pH changes near physiological conditions. In addition, the BCP particles exhibit reversible shape transforming behavior according to orthogonal temperature and pH changes. Colorimetric measurements of temperature and pH changes are enabled by shape-transforming properties combined with selective positioning of dyes, suggesting promising potential for these particles in clinical and biomedical applications.