Palladium Catalysis Of Co / C <sub> 2 </ Sub> H <sub> 4 </ Sub> Copolymerization Kinetic Study

Polyketone (poly-3-oxotrimethylene), alternating copolymer of ethylene and carbon monoxide is a novel semicrystalline thermoplastic high-performance polymeric materials. It offers a broad range of features: outstanding chemical resistance and low permeability; superior strength, wear and friction characteristics, high resistance to fatigue, creep, swelling and repetitive deformation; excellent balance of stiffness and toughness over a wide temperature range; high-quality moldings at short cycle times; resistance to a variety of fuels, organic solvents and aggressive aqueous media; halogen/red phosphor-free flame retardancy. The carbonyl groups contained in polymer backbone abundantly make the material photodegradable. Also, the carbonyl group can be used for derivation to a variety of interesting new materials. The base materials are readily available; furthermore, considerable CO can be regained from industrial exhaust gases of chemistry & metallurgy. In the latest years, it is an important task in CO chemistry taking advantage of industrial exhaust gases contained abundant CO to synthesize polyketone.In the paper, Pd(AcO)₂DPPP was adopted as catalytic precursor in CO/C₂H₄ alternating copolymerization. Synthetical process of copolymerization were optimized by deliberate investigation of reaction conditions, including agitation speed, catalyst concentration, reaction temperature, reaction pressure, monomers composition and acid etc. Then fitter process conditions were gained: agitation speed=750r/min, [Pd]=0.06mmol/L, T=95℃, P=4.0MPa, CO:C₂H₄=1:1, H₂SO₄:Pd=100.The structure and properties of polyketone were characterized by ¹H-NMR,¹³C-NMR and FT-IR, and it was found polyketone was linear alternating copolymer of ethylene and CO, its backbone chain was made up of constitutional unit, — CH₂CH₂CO —, in its ¹³C-NMR spectrum, some thimbleful fragments, — CH₂CH₂CH₂CH₂CO—, were found out. The structures of end-groups were proved to be — COOCH₃ and—COCH₂CH₃.On the ground of the above experimental & analytical results, series of logical assumptions of chain propagation were set, and corresponding kinetic equations wereevaluated. Then, the kinetics parameters of equations were regressed by experiment data of different pressure and monomers composition; at last, CO/C₂H₄ copolymerization kinetic model was accomplished.In the kinetic model, calculated values were consistent with experimental data, in other word, the model was fit for the kinetical description of CO/C₂H₄ copolymerization in methanol.Base on the structure analysis of polyketone and dynamics research, a mechanism of chain growing for CO/C₂H₄ copolymerization using palladium catalyst in methanol is gained, which is composed of two circulations, the main circulation is CO/C₂H₄ insert into growing chain alternately, the hypo- circulation is C₂H₄ insert into growing chain continuously.