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 tetrahydrofuran at ?30°C using (1-methoxy-2-methyl-1-propenyloxy)trimethylsilane (MTS) as an initiator and tetrabutylammonium fluoride monohydrate (TBAF · H₂O) as a catalyst. First, the PMMA macroinitiator was prepared in situ in quantitative conversion and its lifetime was at least 15 min. In the second step, an equimolar amount of ethyl acrylate was polymerized with a conversion of 67–88% and PMMA-block-PEA with number-average molecular weight 5000 < M?_n < 11 500 and polydispersity 1,4 < M?_w/M?_n < 2,1 was obtained. The number of chains almost does not change during the polymerization and the initiating efficiency of MTS was in both steps ca. 0,65–0,80. The diblock structure of the copolymer was confirmed by the ¹³C NMR spectrometric direct proof of the bond-linking of both blocks and by comparing the DSC behaviour of the copolymer with that of the corresponding blend of the homopolymers. No contamination of the block copolymer with the homopolymers was detected by the analytical methods used for the structural characterizations.