Temperature and pH Dual-Responsive Polymer Capsules Prepared by Interfacial Photo-Cross-Linking with Polymers Comprising 6-(Acryloyloxymethyl)uracil

Stimuli-responsive polymer capsules engineered to release encapsulated functional molecules and materials, depending on environmental conditions, are attractive for various applications. In this study, pH and temperature dual-responsive polymer capsules were prepared by interfacial photo-cross-linking with polymer particles comprising 6-(acryloyloxymethyl)uracil (AOMU) units, where we have clarified that the polymers comprising AOMU show triple functions, including photoreactivity and temperature- and pH-responsive properties. Furthermore, the particle morphology yielded after the interfacial photo-cross-linking and washing process depended on the molecular weight of the photoreactive polymers; i.e., the hollow and yolk-like particles were obtained with the moderate-molecular-weight and high-molecular-weight polymers, respectively. Polymer capsules containing a model fluorescent dye were successfully obtained via an encapsulation process with the hollow particles. Finally, we confirmed that the polymer capsules show pH and temperature dual-responsive properties; i.e., the incorporated dyes in the capsules were released under high pH and temperature conditions. We believe that the polymers comprising AOMU have great potential for developing multi-stimuli-responsive polymer materials.