Synthesis of omega- and alpha,omega-sulfonatotelechelics based on homopolymers and block copolymers of n-butyl methacrylate and t-butyl methacrylate

摘要

The synthesis of omega- and alpha,omega-telechelics with sulfonate end groups through the sulfoalkylation of homopolymers and block copolymers of n-butyl methacrylate and t-butyl methacrylate with 1,3-propane sultone is described. The polymerizations are initiated in tetrahydrofuran at -78 degrees C with either 1,1-diphenyl-3-methylpentyllithium or dilithium 1,1,4,4-tetraphenylbutane to obtain monofunctional or difunctional polymethacrylate anions, respectively. Narrow molecular weight distributions are obtained for the homopolymers and copolymers in the presence of LiCl in a 10/1 ratio relative to the initiator. The direct reaction of the poly(n-butyl methacrylate) anions with the sultone results in low functionalization levels: f = 0.24-0.29 for the monofunctional anions and f = 0.32-0.35 for the difunctional anions. The reaction of the poly(t-butyl methacrylate) anions or end-capping of the poly(iz-butyl methacrylate) anions with t-butyl methacrylate units before sulfoalkylation yields telechelics with f = 0.81-1.0 for the monofunctional anions and f = 1.74-1.94 for the difunctional anions. The telechelic polymers, purified by ultrafiltration, have been characterized by size exclusion chromatography, Fourier transform infrared, and H-1 NMR spectroscopy. The yield of the sulfoalkylation reactions, determined by colorimetric analysis of a complex formed with methylene blue, is in good agreement with the results obtained by nonaqueous titration of the acidified telechelics. (C) 2000 John Wiley & Sons, Inc. [References: 32]