Nucleophilic substitution onto poly (methyl methacrylate): 3. Compositional homogeneity of the substituted polymethacrylates

• Published in: Polymer (Guilford) 1977-01, Vol.18 (9), p.937-944
• Main Authors: Bourguignon, J.J., Bellissent, H., Galin, J.C.
• Format: Article
• Language: English
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/0032-3861(77)90139-2

The chemical homogeneity of a series of copolymers obtained by nucleophilic substitution of organolithium reagents RCH 2Li [R = S(C 6H 5), SOCH 3, SO 2CH 3 and SO 2N(CH 3) 2] on a high molecular weight poly(methyl methacrylate) (PMMA, DP n = 700 ) has been studied by different methods, over a wide range of substitution degrees ( 0.14 ⩽ DS m ⩽ 0.76 ). ‘Cross’ fractionation is much more efficient than ‘one direction’ fractionation, and it allows the determination of \ ̄ gs 2 variance values as low as 2 × 10 −4 with sufficient accuracy. The light scattering method is far less sensitive in this range of low compositional polydispersity, even for a suitable system. The fairly high chemical homogeneity observed for all the copolymers, prepared either in homogeneous or heterogeneous solution, may be correlated with both the high molecular weight of the PMMA precursor and the autoretarded kinetics of the substitution process.