Synthesis And Characterization Of High-performance Polyacrylonitrile

PAN was synthesized using azobisisobutyronitrile as initiator by atom-transfer radical polymerization (ATRP) and aqueous suspension, the structural and thermal properties of PAN polymer was investigated by means of Nuclear Magnetic Resonance (NMR), Element Analysis (EA), Fourier Transform Infrared (FTIR), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), X-ray Diffraction (XRD) differential scanning, and Gel Permeation Chromatography (GPC). The main work was shown as follow:FeCl3 coordinated by citric acid (CA) and N-(2-hydroxyethyl) ethylene diaminetriacetic acid (HEDTA) was used for the first time and PAN were synthesized in N,N-dimethylformamide (DMF) by reverse atom-transfer radical polymerization. The PAN with narrow Molecular weight distribution was obtained in the reaction system of AN/AIBN/FeCl3/CA and AN/AIBN/FeCl3/ HEDTA, and the tacticity of PAN was measured by13C NMR and 1HNMR.In order to prepare polyacrylonitrile with high molecular weitht, poly(acrylonitrile-co-maleic acid) was prepared by aqueous suspension polymerization using maleic anhydride as comonomer. At the optimum reaction condition, which was determined by orthogonal experiment method, the Viscosity-average molecular weight of copolymer was 1.16×106. The FT-IR and NMR spectra of the copolymer showed that the structural unit of the comonomer in macromolecular chain was not maleic anhydride but maleic acid. In addition, the thermal properties of poly(AN-co-MAH) was characterized by DSC.The APCA was prepared by the reaction of acryloyl chloride with L-proline according to a method reported previously with a slight modification. The monomer 1-acryloylpyrrolidine-2-carboxylic acid (APCA) was firstly used to copolymerize with acrylonitrile by aqueous suspension polymerization. The poly(AN-co-APCA) with high molecular weight was obtained. Because of low conversion rate of APCA, the cotent of APCA in poly(AN-co-APCA) was less. Effects of APCA on structure and properties of copolymers were investigated. Values of the conversion and the viseosity average molceular weight of copolymers inerease quickly with addition of the comonomer APCA. As the increase of APCA content in the feeding, the thermal properties, degree of crystallinity and grain size of poly(AN-co-APCA) changed in different degree.