Stimuli-Sensitive Core/Shell Microgels

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

This research is aimed at the development of a new class of stimuli-sensitive polymers based on low polydispersity, poly-N-isopropylacrylamide homo- and co-polymer core-shell hydrogel particles (microgels). These nanostructures will allow for a high degree of control over the microgel porosity, deswelling magnitude, sharpness of the volume phase transition (VPT), position of the VPT, responsivity to stimuli other than temperature, number of transitions to a specific stimulus, and kinetics of deswelling. Accordingly, the proposed research is aimed at a systematic investigation of these parameters and their relationship with microgel structure. A suite of techniques including dynamic light scattering, fluorescence resonance nonradiative energy transfer, differential scanning calorimetry, and electron microscopy will be used to investigate the morphology (core compression, core-shell interpenetration, and phase separation) of various core-shell morphologies. The relationship between these structural characteristics and the thermodynamics and kinetics of the volume phase transition will then be investigated in order to establish a rational basis for the construction of complex microgel materials. These studies will then lead to the synthesis of complex multifunctional microgels for two specific applications: (1) fluorescent core-shell particles with ionochromic behavior for applications in metal ion sensing, and (2) hollow shells (via controlled core degradation) for encapsulation and controlled release applications. Taken together, this effort will provide fundamental groundwork for the fabrication of nanostructured hydrogel materials. The significance of this work relates both to its fundamental scientific and societal impact. Scientifically, it will expand our knowledge concerning the chemistry and physics of nanostructured colloidal hydrogels. With respect to broader societal impact, these materials should have tremendous utility in numerous applications such as drug delivery, chemical sensing, chemical/biological separations, photonic materials, artificial muscles, micro-fluidics valves, and cell culture/tissue growth substrates, where advances in chemical sensing and drug delivery will be the focus of this work.