|128. Roos, S.; Müller, A.H.E.: Evidence for transfer in the Atom Transfer Radical Polymerization of n-butyl acrylate, Macromolecular Rapid Communications 21, 864 (2000) -- DOI: 10.1002/1521-3927(20000801)21:12<864::AID-MARC864>3.0.CO;2-E|
Poly(butyl acrylate) (PBuA) of high molecular weight was synthesized by atom transfer radical polymerization (ATRP) in ethyl acetate. Whereas for low molecular weight polymers, a linear increase of the number-average molecular weight, Mn, versus conversion and narrow molecular weight distributions indicate the suppression of side reactions, a downward curvature in the plot of Mn versus conversion was observed for high molecular weights (Mn > 50 000). This effect is explained by chain transfer reactions, leading to branched polymers. GPC measurements with a viscosity detector give evidence for the branched structure of high molecular weight polymers obtained in ATRP. In addition, transfer to solvent or monomer is likely to occur.