High- and low-temperature resistant and intrinsically flame retardant poly(bisphthalazinone thioether sulfone ketone)s: Synthesis, structures and properties

High-performance polymers that are both high temperature resistant and soluble is significant for the development of high-tech fields. 4,4′-(Thiobis(4,1-phenylene))bis(phthalazin-1(2H)-one) (T-BDHPZ) monomer is synthesized by an efficient two-step method using inexpensive phenyl sulfide and phthalic anhydride as raw materials. A series of novel poly(bisphthalazinone thioether sulfone ketone)s (PBPTSKs) were synthesized via aromatic nucleophilic substitution polycondensation. The structures of PBPTSKs were characterized by NMR and FT-IR. These polymers have glass transition temperatures (Tgs) in the range of 302–328 ℃, and are soluble in N-methyl-2-pyrrolidone (NMP), pyridine (Py) and 1,1,2,2-tetrachloroethane (TECT), and partially soluble in N,N -dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dichloromethane (DCM), trichloromethane (TCM) and pyridine. PBPTSK films were prepared by solution casting, and the average light transmittance from 400 to 800 nm of films are all over 70%. PBPTSK boards prepared by hot press molding have outstanding mechanical properties with the tensile strength and the flexural strength of 91–102 MPa and 123–135 MPa, respectively. PBPTSK boards also exhibit excellent high- and low-temperature resistance properties at 290 and −60c, respectively. Moreover, these polymers with bisphthalazinone thioether moiety have outstanding inherent flame retardancy, which pass the V-0 level of the UL-94 test. This provides opportunities to develop high-performance polymers that are both high temperature resistant and soluble, showing great prospects in frontier applications.