Recent advances in the synthesis of cyclic polymers with narrow molecular weight distribution have stimulated theoretical studies to predict the differences in the behavior of cyclic chains and their linear counterparts. Of particular interest from the theoretical and practical viewpoints, are the effects of topology on the coil-to-globule collapse of polymers in solution. The impact of topology on the temperature-induced phase transition of aqueous polymer solutions has been evaluated in the cases of poly(N-isopropylacrylamide) (PNIPAM) and poly(2-isopropyl-2-oxazoline) (PIPOZ). The polymers were obtained by �click� ligation of the corresponding a-azido-?-propargyl-terminated linear polymers.1 The phase transition of their aqueous solutions was monitored by turbidimetry, light scattering, microcalorimetry, and dielectric relaxation measurements.2We observed that, in addition to effects intrinsic to the cyclic topology, such as the intermolecular topological interactions and the absence of end groups, other factors must be considered, such as the cooperativity in the monomer molecular motions and the cooperativity of the hydration/dehydration processes.ReferencesX.-P. Qiu, F. Tanaka, F. M. Winnik, Macromolecules 2007,   40, 7069-7071.Y. Satokawa, T.Shikata, F. Tanaka, X.P.Qiu, F. M. Winnik, Macromolecules 2009,  42, 1400 � 1403.

Influence of topology on the temperature-induced phase transition of polymers: Linear and cyclic poly(N-isopropylacrylamides) and poly(2-isopropyl-2-oxazolines) in water

245th National Meeting (2013)

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