Jieming Li

Synthesis of ω‐ and α,ω‐sulfonatotelechelics based on homopolymers and block copolymers of n‐butyl methacrylate and t‐butyl methacrylate

The synthesis of ω- and α,ω-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 °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(n-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 1H 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.