BLOCK-COPOLYMERS BY SEQUENTIAL GROUP-TRANSFER POLYMERIZATION - POLY(METHYL METHACRYLATE)-BLOCK-POLY(2-ETHYLHEXYL ACRYLATE) AND POLY(METHYL METHACRYLATE)-BLOCK-POLY(TERT-BUTYL ACRYLATE)

Poly(methyl methacrylate)-block-poly(2-ethylhexyl acrylate) (PMMA-bloc k-PEHA) and poly(methyl methacrylate)-block-poly(tert-butyl acrylate) with a methacrylate/acrylate unit ratio of 1 : 1 and 1 : 3, 16000 < M( n)BAR < 44000 and 1,9 < M(w)BAR/M(n)BAR < 2,5, were prepared by sequen tial group transfer polymerization using (1-methoxy-2-methyl-1-propeny loxy)trimethylsilane as initiator and tetrabutylammonium fluoride mono hydrate as a catalyst in tetrahydrofuran at -30-degrees-C, PMMA being the first block. The increase in M(n)BAR during the successive additio n of monomers is linearly dependent on the (co)polymer yield and size- exclusion chromatography (SEC) curves are shifted towards higher molec ular weights in comparison with PMMA macroinitiators. The block struct ure of the copolymers was also proven by extraction experiments. The p resence of homopolymers in the copolymers was not detected. When the f ormer copolymer is prepared in a reverse way (PEHA segment being the f irst), the MMA polymerization ceases at almost-equal-to 43-45% convers ion.