Physico-chemical studies on copolymers of 2-methyleneglutaronitrile and selected derivatives
2-Methyleneglutaronltrlle (MGN) has been prepared by the catalytic dimerisation of acrylonitrile. The radical homopolymerisation of dinitrile monomer was investigated. As a method of preparing PMGN, radical initiation suffers from the drawback of competing reactions, resulting In the formation of oligomeric material of irregular structure.
The anionic polymerisation of MGN was performed using organo lithium and organo magnesium reagents, PMGN prepared by dipiperidino magnesium initiation was characterised.
The radical copolymerisation of MGN with a variety of comonomers was carried out. The tendency of MGN to form alternating copolymers with “donor” monomers was observed. The spectroscopic, thermal, and thermomechanical properties of selected copolymers was determined.
Proton nmr studies Identified the presence of weak electron donor-acceptor comonomer complexes in CCl4 solutions of MGN/isoprene and MGN/Î±-methyl styrene.
The mechanism of the alternating copolymerisations of MGN/isoprene and MGN/Î±-methyl styrene were investigated in terms of the possible involvement of such complexes using a non-linear least squares curve fitting analysis of the compositions of copolymers prepared over a wide comonomer composition range. The analysis coupled with a statistical testing method reveals that in both systems, invoking complex participation does not provide a statistically significant improvement, over the standard Mayo-Lewis terminal model, in the ability to describe the experimental data.
The possible origin(s) of the small deviations observed between the experimental copolymer compositions and those predicted by the Mayo-Lewis model are discussed. In the MGN-isoprene systems, such deviations may be explained by invoking diene propagation in more than one chemically distinguishable form.
A number of derivatives of MGN have been prepared by elementary chemical reactions. The feasibility of preparing liquid crystalline monomers based on one such derivative, 2-methyleneglutaric acid, has been demonstrated.