Synthesis of Thermo-Responsive Polymers With Both Tunable UCST and LCST

• Published in: Macromolecular rapid communications. 2011-04, Vol.32 (8), p.660-664
• Main Authors: Tian, Hai-Ying, Yan, Jun-Jie, Wang, Di, Gu, Chen, You, Ye-Zi, Chen, Xue-Si
• Format: Article
• Language: English
• Subjects: Block copolymers; Chain transfer; Glycols; LCST; Methacrylamide; Methacrylates - chemistry; Polymerization; Polymers; Polymers - chemical synthesis; Polymers - chemistry; RAFT; Rafts; stimuli-responsive polymers; Synthesis; Temperature; UCST
• ISSN: 1022-1336; 1521-3927; 1521-3927
• DOI: 10.1002/marc.201000713

New water‐soluble block copolymers of 2‐(2‐methoxyethoxy)ethyl methacrylate (MEO2MA), oligo(ethylene glycol) methacrylate (OEGMA), and N‐(3‐(dimethylamino) propyl) methacrylamide (DMAPMA) (poly(OEGMA‐co‐MEO2MA)‐b‐poly(DMAPMA)) were prepared via sequential reversible addition‐fragmentation chain transfer (RAFT) polymerization. Selective quaternization of poly(DMAPMA) block gives poly(OEGMA‐co‐MEO2MA)‐b‐poly((3‐[N‐(3‐methacrylamidopropyl)‐N,N‐dimethyl]ammoniopropane sulfonate)‐co‐N‐(3‐(dimethylamino) propyl) methacrylamide), such block copolymer exhibits double thermo‐responsive behavior in water, poly(MEO2MA‐co‐OEGMA) block shows a lower critical solution temperature (LCST), and poly((3‐[N‐(3‐methacrylamidopropyl)‐N,N‐dimethyl]ammoniopropane sulfonate)‐co‐N‐(3‐(dimethylamino) propyl) methacrylamide) block shows a upper critical solution temperature (UCST). Both of LCST and UCST can be controlled: LCST could be tuned by the fraction of OEGMA units in poly(OEGMA‐co‐MEO2MA), and UCST was found to be dependent on the degree of quaternization (DQ). A novel thermo‐sensitive diblock copolymer with both UCST and LCST has been prepared via RAFT polymerization. The LCST could be finely controlled by tuning the fraction of OEGMA units in the random copolymer, and the UCST could be easily tuned by the degree of quaternization (DQ) of poly(OEGMA‐co‐MEO2MA)‐b‐poly(DMAPMA).