The Preparation Of The Conjugated Polymer-poly(Phenylacetylene)with High Molecular Weight And The Research Of Its Degradation Ability

As one of substituted polyacetylenes,polyphenylacetylene?PPA?has specific optical,electrical and magnetic properties,and has been widely applied in the fields of plastic electronics,organic ferromagnet,photovoltaic cell,electroluminescent materials,electrochemical sensors,molecular devices and others.Currently,it has been reported that the molecular weight of PPA plays an important role in its electrical conductivity.The electrical conductivity of PPA increases significantly with the increase of the molecular weight of PPA.Although there are lots of methods about synthesizing PPA and its derivatives,the synthesis of PPA with high molecular weight and narrow molecular weight distribution is rarely reported in the literatures.Therefore,preparing PPA with high molecular weight and narrow molecular weight distribution will have a significant impact on the applications of PPA in the fields of photoelectric,medicine,chemical industry.This paper is aimed to synthesize PPA with high molecular weight and narrow molecular weight distribution using organosilane compound as an initiator and transition metal complex as a catalyst.The major work of this thesis is as follows:1.High molecular weight PPA was synthesized by the polymerization of phenylacetylene?PA?initiated by organosilane compounds and catalyzed under the catalysis of a platinum metal complex.The effects of various polymerization conditions,such as the type of initiator and catalyst,the concentration of the catalyst,initiators,and monomer,the polymerization temperature,the polymerization time and the reaction atmosphere,on the molecular weight of PPA were investigated.The results showed that the synthesized PPA had a number-average molecular weight of4.14×10⁵ and a weight-average molecular weight of 6.97×10⁵,with the polydisepersity index?PDI?of 1.68.2.The obtained PPA conjugated polymers were characterized by ¹H-NMR,FT-IR,UV-Vis,XRD and TGA.The results demonstrated that the obtained PPA mainly possesses a cis-structure?cis=95.69%?,indicating excellent stereoregularity of the polymers.The XRD analysis showed that PPA has poor crystallinity,and is primarily amorphous structure.3.The effects of the concentration of catalyst and initiator,the polymerization temperature on the polymerization rate and the monomer conversion were investigated.The results showed that there was a good linear relationship between ln?[M]₀/[M]_t?and reaction time?t?,which meaned that the polymerization rate was at first order kinetics with respect to monomer concentration.The apparent activation energy?E_a?of the PA polymerization reaction was determined to be 23.75 KJ/mol,with a pre-exponential factor?A?of 212.07 min^-1.4.The degradation behavior of PPA in tetrahydrofuran,chloroform and toluene were investigated.The influences of the reaction atmosphere on the degradation of PPA were studied.The experimental results showed that PPA degraded fastest in chloroform,but slowest in toluene.In addition,the degradation behavior of PPA in a solvent was more significant in the air than in nitrogen atmosphere.