Bridgette M. Budhlall, University of Massachusetts, Lowell, MA, Orlin D. Velev, North Carolina State University, Raleigh, NC, and Manuel Marquez, Phillip Morris USA, Richmond, VA.
Microwave-, photo- and thermo-responsive polymer microgels that range in size from 100-800 nm and are swollen with water were prepared by a novel microarray technique. We utilized a liquid-liquid dispersion technique in a system of three immiscible liquids to prepare PNIPAm-co-AM core-shell microcapsules loaded with AuNP. The spontaneous encapsulation of the core-shell droplet morphology to form a double oil-in-water-in-oil (o/w/o) emulsion is facilitated by the control of the interfacial energy balance between the aqueous phase (in which a water-soluble drug can be dissolved), the monomer phase and the continuous phase. The water-in-oil (w/o) droplet containing 26 wt% PNIPAm-co-Am monomer, 0.1 wt% Tween-80 surfactant, FITC fluorescent dye and colloidal gold nanoparticles spontaneously developed a core-shell morphology that was fixed by in situ photopolymerization. Our results demonstrate the development of new reversibly swelling and deswelling AuNP/PNIPAm hybrid core-shell microcapsules and microgels that can be actuated by visible light and/or microwave radiation (<1100 nm) and/or temperature. These microgels can have potential applications into microfluidic switches, photosensors, micromachines, and various nanomedicine applications in controlled delivery and release.
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