Kinetics of Collapse Transition and Cluster Formation in a Thermoresponsive Micellar Solution of P(S-b-NIPAM-b-S) Induced by a Temperature Jump

Joseph Adelsberger, Ezzeldin Metwalli,Alexander Diethert, Isabelle Grillo, Achille M. Bivigou-Koumba, André Laschewsky, Peter Müller-Buschbaum, Christine M. Papadakis
Macromolecular Rapid Communications Volume 33, Issue 3, pages 254–259, February 13, 2012

Abstract

Structural changes at the intra‐ as well as intermicellar level were induced by the LCST‐type collapse transition of poly(N‐isopropyl acrylamide) in ABA triblock copolymer micelles in water. The distinct process kinetics was followed in situ and in real‐time using time‐resolved small‐angle neutron scattering (SANS), while a micellar solution of a triblock copolymer, consisting of two short deuterated polystyrene endblocks and a long thermoresponsive poly(N‐isopropyl acrylamide) middle block, was heated rapidly above its cloud point. A very fast collapse together with a multistep aggregation behavior is observed. The findings of the transition occurring at several size and time levels may have implications for the design and application of such thermoresponsive self‐assembled systems.

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