Reexamination of Slow Dynamics in Semidilute Solutions: Temperature and Salt Effects on Semidilute Poly(N-isopropylacrylamide) Aqueous Solutions

摘要: One fast and one slow relaxation mode were observed in semidilute aqueous solution of poly(N-isopropylacrylamide) (PNIPAM) by dynamic light scattering (DLS). The length scale the was found to be comparable with observation (1/q) our DLS measurements. To elucidate its origin, we varied temperature used different salts study their effects on such a because it is known that they can influence strength water−amide hydrogen bonding as well icelike structure liquid water. As increases, gradually suppressed. Using strong salting-out salt (Na2SO4) salting-in (NaSCN) same cation two model systems, suppresses dynamics, while amplifies it. Our results reveal related long-range correlated density or concentration fluctuation, namely, interaction among segments different...