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Synthesis of Thermoresponsive Copolymers with Tunable UCST‐Type Phase Transition Using Aqueous Photo‐RAFT Polymerization
Author(s) -
Lertturongchai Pattida,
Ibrahim Mohamed I. A.,
Durand Alain,
Sunintaboon Panya,
Ferji Khalid
Publication year - 2020
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.202000058
Subject(s) - upper critical solution temperature , copolymer , materials science , polymerization , polymer chemistry , cloud point , thermoresponsive polymers in chromatography , lower critical solution temperature , polymer , aqueous solution , chemical engineering , phase (matter) , chemistry , organic chemistry , composite material , reversed phase chromatography , engineering
Currently, the phase transition of aqueous binary systems containing thermoresponsive (co)polymers, and exhibiting upper critical solution temperature (UCST), is exclusively investigated in dilute solutions, which can limit the knowledge of their UCST‐type phase transition. Herein, a photo‐RAFT polymerization approach, using acrylamide (AAm) and acrylonitrile (AN) as monomer models, is used to prepare well‐controlled poly(AAm‐ co ‐AN) copolymers “in situ” in highly concentrated dispersions (60 wt%). The impact of the copolymer concentration and the chemical composition (as a variation of AN fraction in the copolymers) on the cloud point temperature ( T CP ) are investigated using turbidity measurements. Importantly, the results show that upon increasing the polymer concentration, a sharp increase of T CP up to a maximum point is observed, representing the UCST, before the decrease of T CP at higher polymer concentrations. Finally, a model equation is developed to fit the UCST values of poly(AAm‐ co ‐AN), which can be useful to design new poly(AAm‐ co ‐AN) copolymers with a desired UCST for a specific application.