Synthesis and complexation of well-defined labeled poly(N,N-dimethylaminoethyl methacrylate)s (PDMAEMA)

We present the synthesis and characterization of well-defined polycationic copolymers containing thiazole dyes in the side chain. Atom transfer radical polymerization (ATRP) was used for the copolymerization of 3-azidopropyl methacrylate (AzPMA) and N,N-dimethylaminoethyl methacrylate (DMAEMA) of different composition. Thiazole-based alkyne-functionalized dyes (e.g., 5-methyl-4-(prop-2-yn-1-yloxy)-2-(pyridin-2-yl)thiazole, (MPPT)) were afterwards covalently attached using copper catalyzed azide alkyne cycloadditions (CuAAC) reaching contents of up to 9 mol % dye. Subsequent quaternization of the tertiary nitrogen of DMAEMA with strong methylation agents (e.g., methyl iodide) led to permanently charged polyelectrolytes. The materials were characterized by size exclusion chromatography, as well as NMR- and UV/VIS-spectroscopy. Particular attention is paid to the spectroscopic properties of the dyes in the side chain upon environmental changes such as pH and salinity. We anticipate the application of such precisely functionalized polyelectrolytes as temperature- and pH-responsive sensors in biomedical applications, e.g., within interpolyelectrolyte complexes. Concerning the latter, first complex formation results are demonstrated.