P(AN/IA) copolymers were obtained in a mixture solution of tetramethylene sulfone (TMS)/water and other four different polymerization mediums and polymer conversion rate

weight average molecular weight (Mw) and molecular weight distribution (D)

surface micro-topography

monomer reactivity ratios

chain structure

thermal property and spinning performance were investigated.The results showed that with an increase of H2O in the mixed solvent mixture

the polymer conversions were increased firstly and then decreased.The experimental results showed that there were good linear relationships between the weight average molecular weight (Mw) and the ratio of H2O/TMS as well as the other four different polymerization mediums.But Mw and D(less than 2) of P(AN/IA) polymer obtained in H2O/TMS mixture reached the maximum and the minimum

respectively

compared with the other polymerization systems.AN copolymerized with IA in H2O/TMS mixture tended to ideal polymerization

according to statistical predication

the distributing probability of 2IA segment was only 2.83%.Looser structure

smaller particle size

more soluble

lower heat release rate

wider heat release range

smaller reaction energy barrier were required by thermal stabilized ladder-like structure during cyclization reaction of PAN copolymer which could be obtained in H2O/TMS mixture.The apparent viscosity of spinning dope was lower and TMS was an excellent solvent for PAN.