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Translating Thermal Response of Triblock Copolymer Assemblies in Dilute Solution to Macroscopic Gelation and Phase Separation
Author(s) -
Sun Zhe,
Tian Ye,
Hom Wendy L.,
Gang Oleg,
Bhatia Surita R.,
Grubbs Robert B.
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201609360
Subject(s) - copolymer , aqueous solution , ethylene oxide , micelle , polymer , materials science , chemical engineering , polymer chemistry , phase (matter) , lower critical solution temperature , amphiphile , phase transition , chemistry , thermodynamics , organic chemistry , composite material , physics , engineering
The thermal response of semi‐dilute solutions (5 w/w%) of two amphiphilic thermoresponsive poly(ethylene oxide)‐ b ‐poly( N , N ‐diethylacrylamide)‐ b ‐poly( N , N ‐dibutylacrylamide) (PEO 45 ‐PDEAm x ‐PDBAm 12 ) triblock copolymers, which differ only in the size of the central responsive block, in water was examined. Aqueous PEO 45 ‐PDEAm 41 ‐PDBAm 12 solutions, which undergo a thermally induced sphere‐to‐worm transition in dilute solution, were found to reversibly form soft ( G ′≈10 Pa) free‐standing physical gels after 10 min at 55 °C. PEO 45 ‐PDEAm 89 ‐PDBAm 12 copolymer solutions, which undergo a thermally induced transition from spheres to large compound micelles (LCM) in dilute solution, underwent phase separation after heating at 55 °C for 10 min owing to sedimentation of LCMs. The reversibility of LCM formation was investigated as a non‐specific method for removal of a water‐soluble dye from aqueous solution. The composition and size of the central responsive block in these polymers dictate the microscopic and macroscopic response of the polymer solutions as well as the rates of transition between assemblies.