Metal-Free Synthesis of Responsive Polymers: Cloud Point Tuning by Controlled "Click" Reaction

Nitroxide-mediated radical polymerization has been used for the preparation of pentafluorostyrene (PFS) homopolymers and random copolymers of PFS and oligo(ethyleneglycol) methacrylate (OEGMA(8.5)). The poly(pentafluorostyrene) homopolymers were reacted with thiophenol at different ratios at room temperature in the presence of triethylamine. The "clicked" polymers were characterized by H-1 and F-19 NMR spectroscopy and size exclusion chromatography. Moreover, the copolymerization kinetics of the PFS and OEGMA(8.5) copolymers was followed, and the phase transition behavior of random copolymers with different compositions was discussed. Furthermore, copolymers of PFS and 2-(dimethylamino) ethyl methacrylate (DMAEMA) were prepared at various mole ratios, and the copolymer with a 10:90 ratio, respectively, was soluble in water at room temperature. Turbidimetry measurements were performed for PFS and OEGMA(8.5) or DMAEMA copolymers to determine their cloud points. Finally, the PFS and OEGMA(8.5) copolymer with a mole ratio of 60:40 was reacted further with thiophenol to increase the hydrophobic part in the copolymer. The cloud points of the obtained copolymers could be tuned from 87 to 33 degrees C by using not only the controlled radical polymerization but also the "click" reaction in a controlled fashion. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1278-1286, 2010