High-Molecular-Weight Alternating Copolymers from Thermal Copolymerizations of N-Alkylcitraconimides with Styrene

Radical copolymerizations of eight N-alkylcitraconimides (1) and styrene (2) were carried out in the presence or absence of a radical initiator. Alternating copolymers with number-average molecular weights higher than 7 × 10⁵ were obtained from the thermal copolymerizations (monomer molar ratio = 1:1) in bulk at 60°C. The spontaneous copolymerization is considered to be by induced radicals produced via an intermediate Diels-Alder dimer and minary a contact-type charge transfer complex between N-alkylcitraconimide and styrene. Thermogravimetric analyses indicate the resulting copolymers have high thermal stabilities.