Synthesis of Dual-Stimuli-Responsive Microcontainers with Two Payloads in Different Storage Spaces for Preprogrammable Release

Abstract

Stimuli-responsive microcontainers have become a major topic of interest, from fundamental aspects to applications in materials science. However, microcontainers that enable the loading of multiple species and programmable release are mostly unexplored. Herein, we describe the design and synthesis of a dual-responsive organic/inorganic hybrid microcontainer with two payloads in separate storage spaces that is formed by the rapid UV-initiated polymerization of Pickering emulsions. The stellate mesopore silica nanoparticles with poly(N-isopropylacrylamide) grafted inside the mesopores were loaded with one compound (Nile red) and used as Pickering emulsifiers to stabilize oil-in-water droplets. Upon UV irradiation, pH-responsive monomers were polymerized in the presence of 5(6)-carboxyfluorescein diacetate (CFDA) to form hybrid colloidal microcontainers. The release of Nile red and CFDA could be selectively activated by changing the temperature or pH value.

Keywords: Pickering emulsion polymerization; mesoporous materials; microcontainers; nanoparticles; organic-inorganic hybrid composites.