Novel cardo poly(arylene ether nitrile sulfone) copolymers bearing xanthene moiety in the main chain

Abstract

A series of cardo poly(arylene ether nitrile sulfone) (PENS) copolymers containing xanthene moiety were prepared by the nucleophilic substitution reaction of 9,9-bis(4-hydroxyphenyl)xanthene with 2,6-difluorobenzonitrile (DFBN) and 4,4′-dichlorodiphenylsulfone (DCDPS) by varying stoichiometric ratio of DFBN to DCDPS (90/10–40/60) using N, N-dimethylacetamide (DMAc) as solvent in the presence of anhydrous potassium carbonate. The copolymers having number-average molecular weights of 17,100–18,300 g mol−1 with the polydispersity index from 1.79 to 2.11 were amorphous and were easily soluble in polar solvents such as N-methyl-2-pyrrolidone and DMAc, and even in tetrahydrofuran and chloroform at room temperature. The resulting PENS copolymers showed glass transition temperature ( Tg) between 253.3°C and 260.4°C, and the Tg values were found to increase with increasing sulfone content in the copolymers. Thermogravimetric studies showed that all the polymers were stable up to 450°C, with 10% weight loss temperatures ranging from 500°C to 524°C and char yields of 56–63% at 700°C under nitrogen atmosphere. All new polymers could be cast into strong and flexible films with tensile strengths of 56.7–78.8 MPa, elongations at break of 7.8–9.1%, and tensile moduli of 2.1–3.2 GPa.