Effect of monomethyl itaconate on thermal stabilization and rheological properties of narrow polydispersity polyacrylonitrile synthesized in continuous flow

For simultaneously enhancing the stabilization and spinnability of polyacrylonitrile (PAN), monomethyl itaconate (MI) with ester group and carboxyl was chosen as the bifunctional comonomer. Poly(acrylonitrile-monomethyl itaconate) [P(AN-MI)] copolymers with narrow polydispersity were successfully synthesized in continuous flow. Their compositions, molecular characteristics and structures were analyzed. Moreover, the effect of MI on the cyclization reactions and stabilization process of PAN was studied and kinetics of cyclization reactions were further investigated. Compared to PAN homopolymer, P(AN-MI) copolymers possess lower activation energies and greater extents of cyclization reactions. Moreover, it is found that 2 wt% is the most optimal MI concentration in the feed for preparing PAN with high yield, acceptable molecular weight, narrow polydispersity and great thermal stabilization. Rheological analysis was performed to explore the effect of MI incorporation on the rheological properties of PAN solution for better regulating spinning process parameters.