Solution Behavior of Poly(n-Isopropylacrylamide) in Water: Effect of Additives

Abstract

The effect of different kinds of additives (electrolytes, nonelectrolytes, hydrotropes, and surfactants) on the cloud point (CP) of low molecular weight and narrow dispersed poly(n-isopropylacrylamide) (PNIPAM) synthesized via reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization was examined. The CP showed a concentration dependent variation and it is greatly modified in the presence of additives. The size of the random polymer coil at 30°C obtained from dynamic light scattering (DLS) measurements is often influenced by the presence of additives. We have explained the effects of different additives on PNIPAM in terms of their interaction with polymer and resultant changes in the coil structure.

Keywords:

• Cloud point
• coil-to-globule transition
• dynamic light scattering
• poly(n-isopropylacrylamide)

Acknowledgments

Financial assistance from UGC Project No. F.31-145/2005 (SR) is gratefully acknowledged.