(746a) Synthesis and Swelling Response of Block and Random Copolymer Brushes Incorporating Thermo- and pH-Responsive Constituents

Layers of end-tethered polymer chains ? so-called ?polymer brushes? ? are of interest for their ability to straddle the fluid-solid interface and impart new and useful properties to the underlying surface. Because brushes adjust their structure when environmental conditions change, a strategy to enrich the properties of the interfacial layer is to integrate multiple components into the brush and use constituent materials that exhibit, for example, pH-, temperature-, or photo-responsive behavior. In this work, polymer brushes consisting of poly(N-isopropylacrylamide) and poly(methacrylic acid) were grown by surface initiated, photoiniferter-mediated photopolymerization. To create bi-level, block copolymer brushes, tetraethylthiuram disulfide (TED), a source of deactivating radicals, must be added to establish and maintain the equilibrium between dormant and active (growing) chains during photopolymerization. Layers consisting of either block or random copolymers were synthesized and characterized in the dry and solvated states using multi-angle ellipsometry. The swelling response of the solvated homopolymer and copolymer brushes as a function of pH, temperature and ionic strength will be discussed, highlighting how the chemical information encoded into the brush chains determines swelling behavior.