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

Abstract

AbstractRadical copolymerizations of allyl a‐(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°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 (Kc), cyclization (kcyc), 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: Kc = 0,20 ± 0,01 and 0,05 ± 0,005 L/mol in CH3COOH‐d4 at 35 ± 0,1°C (1H NMR method) for D…AMI and AMI… A complexes, respectively; kcyc · 105 = 1.71 and 0,66 L/(mol · s), r1 = 0,13 ± 0,01 and 0,037 ± 0,002, r2 = 0,048 ± 0,002 and 0,052 ± 0,002 (by Kelen‐Tüdőş method), k12/k21 = 0,20 and 0,62, k1c/k12 = 0,6 and 29,8, k2c/k21 = 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°C, 30 min) and/or by UV‐irradiation (25°C, 15 min), which was confirmed by DTA and TGA analyses.