Synthesis and characterization of surface-cyanofunctionalized poly(N-isopropylacrylamide) latexes

A series of P[N-isopropylacrylamide (NIPAM)] latexes with different content s of cyano groups were successfully prepared by either seeded or shot-growt h polymerizations of an aqueous solution containing acrylonitrile (AN) onto a seed P[NIPAM] latex, respectively, and further characterized by FT-IR,H- 1-NMR, elemental analysis, as well as by quasielastic light scattering (QEL S) and scanning electron microscopy (SEM). All prepared surface-cyanofuncti onalized P[NIPAM] latexes exhibited the same range of lower critical soluti on temperature (LCST) as a pure P[NIPAM] latex. The shot polymerization pro cess proved more efficient at yielding cyano derivatized latexes than the s eeded polymerization technique. The amount of incorporated cyano groups ont o the particles was determined with a good correlation both by H-1-NMR and elemental analysis. The higher the amount of initially introduced AN monome r in the reaction mixture, the more cyano groups were incorporated onto the particles. The surface of the particles with high content of cyano groups appeared quite rough by SEM in comparison with that of the pure P[NIPAM] pa rticles.