Light- and Temperature-Programmed Block Copolymer Capsules with Tunable Shell Nanostructures

Abstract

Abstract Polymer capsules capable of adopting distinct shell nanostructures in response to external stimuli are attractive microcompartments for encapsulation, separation, and triggered release. Realizing such capsules requires orthogonal control, in which distinct stimuli independently define the structural outcome. Here, we report a light- and temperature-programmed assembly strategy for hollow polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) capsules with tunable shell nanostructures. The key to this dual responsiveness is a photocleavable thermoresponsive additive, in which an amide-based thermoresponsive backbone sets the transition temperature and a photocleavable comonomer encodes the light response. During emulsion-confined assembly, photocleavage shifts the lower critical solution temperature of the additive and redistributes it between the aqueous and organic phases, selecting either concentric lamellar or cylindrical shells at a given temperature. Replacing the poly(N-isopropylacrylamide) backbone with poly(N-isopropylmethacrylamide) raises the operating temperature from 27 to 50 °C, whereas replacing the o-nitrobenzyl group with a coumarin unit shifts photoactivation from 365 to 410 nm and reverses the direction of the light-driven morphology selection. This modular design offers a versatile strategy for programming BCP capsule shell morphologies under user-defined thermal and optical conditions.