Complex-radical cyclocopolymerization of allyl a-(N-maleimido)acetate with styrene and maleic anhydride

Radical copolymerizations of allyl alpha-(N-maleimido)acetate (AMI) with styrene (D, electron-donor) or maleic anhydride (A, electron-acceptor) were carried out in benzene and/or methyl ethyl ketone (MEK) at 50-70 degrees C in the presence of 2,2'-azoisobutyronitrile (AIBN) as initiator. The structure and properties of copolymers synthesized were derived from IR, chemical, DTA and TGA analyses. Side-chain unsaturation of macromolecules was also proved by the crosslinking effect observed. Kinetic parameters of copolymerization such as complex-formation (K-c), cyclization (k(cyc)), and copolymerization constants and ratios of chain growth rates for the participation of monomer charge transfer complexes (CTC) and free monomers for both systems were obtained: K-c = 0,20 +/- 0,01 and 0,05 +/- 0,005 L/mol in CH3COOH-d(4) at 35 +/- 0,1 degrees C (H-1 NMR method) for D...AMI and AMI... A complexes, respectively; k(cyc) . 10(5) = 1.71 and 0,66 L/(mol . s), r(1) = 0,13 +/- 0,01 and 0,037 +/- 0,002, r(2) = 0,048 +/- 0.002 and 0,052 +/- 0,002 (by Kelen-Tudos method), k(12)/ k(21) = 0,20 and 0,62, k(1c)/k(12) = 0,6 and 29,8, k(2c)/k(21) = 4,8 and 9,1 for the D-AMI and AMI- A systems, respectively. The results show that alternating cyclocopolymerization reactions are realized which are carried out via a ''mixed'' mechanism in the D-AMI system and via a ''complex'' mechanism in the AMI-A system, with formation of cyclolinear macromolecules containing side-chain unsaturated fragments of ''allyl'' (D-AMI copolymer) and ''imide' (AMI-A copolymer) types. The synthesized copolymers easily undergo crosslinking by thermotreatment (105 degrees C, 30 min) and/or by UV-irradiation (25 degrees C, 15 min), which was confirmed by DTA and TGA analyses.