Aqueous solution and photophysical properties of cationic poly(trimethyl methacrylamidophenyl ammonium methylsulfate) and zwitterionic poly(N,N-dimethylmethacrylamidophenyl ammonium propane sultone)

Water-soluble polymers, cationic poly(trimethyl methacrylamidophenyl ammonium methylsulfate) [poly(TMMAPhAMS)] and zwitterionic poly(N,N-dimethylmethacrylamidophenyl ammonium propane sultone) [poly(DMMAPhAPS)], derived from N,N-dimethylaminophenyl methacrylamide (DMAPMA) were studied in terms of their solubility, viscosity, ultraviolet absorption, fluorescence properties, quasielastic light scattering and surface activity. The critical solution temperature of poly(DMMAPhAPS) and poly(TMMAPhAMS) observed was below 0°C showing that both have good solubility. These water-soluble polymers exhibited both ultraviolet absorption and fluorescence emission properties. The ultraviolet absorption of poly(DMMAPhAPS) (245 nm) showed a 2 nm red shift as compared to that of poly(TMMAPhAMS) (243 nm), suggesting that the microenvironment around the phenyl moiety of poly(DMMAPhAPS) is more hydrophobic in poly(TMMAPhAMS). With increasing salt concentration, the average hydrodynamic diameter of cationic poly(TMMAPhAMS) decreases from 640 to 200 nm, while that of poly(DMMAPhAPS) increases from about 300 to 750 nm. The surface tension of zwitterionic poly(DMMAPhAPS) decreases continuously in an almost linear dependence on logarithm concentration at higher polymer concentrations (>2.5×10−3 M), with no break indicative of micelle formation.