POLY(METHYL METHACRYLATE)-BLOCK-POLY(ETHYL ACRYLATE) BY GROUP-TRANSFER POLYMERIZATION - SYNTHESIS AND STRUCTURAL CHARACTERIZATION

Poly(methyl methacrylate)-block-poly(ethyl acrylate) (PMMA-block-PEA) was synthesized by sequential group transfer polymerization (GTP) in t etrahydrofuran at -30-degrees-C using (1-methoxy-2-methyl-1-propenylox y)trimethylsilane (MTS) as an initiator and tetrabutylammonium fluorid e monohydrate (TBAF . H2O) as a catalyst. First, the PMMA macroinitiat or was prepared in situ in quantitative conversion and its lifetime wa s at least 15 min. In the second step, an equimolar amount of ethyl ac rylate was polymerized with a conversion of 67 - 88% and PMMA-block-PE A with number-average molecular weight 5 000 < M(n)BAR < 11 500 and po lydispersity 1,4 < M(w)BAR/M(n)BAR < 2,1 was obtained. The number of c hains almost does not change during the polymerization and the initiat ing efficiency of MTS was in both steps ca. 0,65 - 0,80. The diblock s tructure of the copolymer was confirmed by the C-13 NMR spectrometric direct proof of the bond-linking of both blocks and by comparing the D SC behaviour of the copolymer with that of the corresponding blend of the homopolymers. No contamination of the block copolymer with the hom opolymers was detected by the analytical methods used for the structur al characterizations.