Study On Molecular Design And Property Of Novel Crosslinkable Poly (Aryl Ether Ketone)s

Accompany with the development of high-technology, high-performanceengeering thermoplastics have been paid much attention while the demandingto materials become more and more critical. Poly( ether ether ketone) (PEEK),which is the typical representative in Poly(aryl ether ketone)s (PAEKs) family,have been applied in electronics, transports, aerospace fields et al for itsoutstanding properties such as high thermal stability, radiation resistance, highmodulus. The physical properties of the polymers depend very much on thechemical structure. Therefore new monomers containing substituent groupwere designed and synthesized to introduce into chain of PAEKs. The difficulty encountered during the development of new PAEKS must be ascribed to the common shortcoming of thermoplastics. On the contrary, the thermosets can be processed at lower temperature and be applied at higher temperature while they cannot be found to a mold. So we hope to develop a kind of material which can be processed as thermoplastics and being used as thermosets. Cross-linking is a suitable and powerful method to transform thermoplastics to thermosets. Here cross-linkable propenyl group was introduced to the side chain of PEEK. A novel soluble poly(ether ether ketone) with propenyl groups aslateral substituents was synthesized through nucleophilic substitution route. Monomer 3,3'-dially-4,4'-dihydroxybiphenyl (DABP) was synthesized byMeerwein aryl-substitution reaction and based on Clasein arrangement. Polymerswere also prepared through the nucleophilic substitution displacement reactionwith activated difluoro monomer 4-4'difluorobenzophenone and monomer3,3'-dially-4,4'-dihydroxybiphenyl (DABP) with K2CO3 as base, N,N-Dimethyl 70吉林大学硕士学位论文formamide(DMF) was used as a solvent at 160℃ for 5h. The reaction mixturewas poured into large distilled water and continuous turning and polymermaterials were obtained. After the crude product was crushed, filtered, washed,and dried, a new pendant group, propenyl was developed to functionalize PEEKby a novel process-polycondensation-in situ isomerization. It was characterizedand studied its properties by FTIR, H-NMR ,UV-Vis , WAXD, GPC and DSC. 1 Existing of substituent pendant groups destroyed the crystal property of thesepolymers with high molecular weight. These polymers containing pendantpropenyl were soluble well in organic solvents such as DMF, DMAC, THF, andthe membrane material had high intension and tenacity properties. The thermal properties of soluble polymer containing pendant propenyl weremagnitude change. The suitable cross-linking condition was determinded by DSC.There was no linearly change on the glass transition temperature (Tg) of polymerheat treated at 250oC or 280oC . The glass transition temperature (Tg) of polymerincreased linearly after the polymer was cured by heat treat at 320oC. It was showthat 320oC is the suitable crosslinking temperature under nitrogen atmosphere orO2 atmosphere. When the polymer irradiated by UV, its Tg not increased linearlywith irradiation times increasing. But Gel phenomina was show when polymerwas heat treated or irraditioned by UV. The results indicated that the crosslinkingstructure had formed when polymer materials were heat treated or irradioned byUV. At the same time, the polymer's thermal stability was elevated aftercross-linking.