High molecular weight polyetherketones based on 4-(4-hydroxyphenyl)-1-phthalazinone (DHPZ)/4,4'-thiobisphenol TBP/4,4'-diflourodiphenylketone(DFK) were prepared by aromatic nucleophilic substitution reaction involving the toluene, N-methyl-2-pyrrolidone (NMP) and anhydrous potassium carbonate. The copolymer having 50% TBP molar content was characterized by FT-IR and H-1-NMR. The results indicated that the copolyetherketones contained sulfide and phthalazinone moieties. C-13-NMR spectra were used to indentify the structure of copolyetherketones. According to C-13-NMR spectra,it was found that the structural repeat units were randomly distributed in the molecular chain of the copolyetherketones. The Glass transition temperatures (T-g) were determined by differential scanning calorimetry (DSC) after being kept 5 min to remove the thermal history and cooling to room temperature at approximately 100 K/min, the results showed that no melting point temperature was detected and all the polyetherketones have only one T-g in the range of 137degreesC to 263degreesC and the T(g)s decrease linearly with the increase of sulfide moiety in the copolymers, which further indicated all of the polyetherketones are random or homogeneous. The wide angle X-ray scattering was used to detected the crystallization of copolyetherketones. No crystal was formed for all the samples containing less than 70% TBP structure in the copolyetherketones and the polyetherketone polymerized by DFK and TBP was semicrystallization having melting point temperature of about 262degreesC The results of the copolymers stress-strain behavior indicated that,with the increase of sulfide moiety in the copolymers from 10% to 30%, the strain at break increased obviously. The solubility tests showed that the copolymers having more phthalazinone moiety have better solubility in some polar solvents.
