Living Addition Polymerization Of Cyclopropenes Catalyzed Palladium(?)complex

As the smallest cyclic and unsaturated compound in nature,cyclopropeneis composed of two saturated C-C bonds and one unsaturated C=C bond.Cyclopropenes have the high reactivity largely due to their enormous ring strain.It serves as important synthetic intermediate in organic chemistry as well as unique monomer unit in polymerization.The cyclopropenes can be so far polymerized by two pathways:i)addition polymerization,ii)ring-opening metathesis polymerization.In recent years,the transition metal-catalyzed ring-opening metathesis polymerization of cyclopropene has revealed the rich metathesis reactivities.However,there are still challenges on the addition polymerization of cyclopropane,such as the living addition polymerization of cyclopropene,stereoregularity and so on.Therefore,the content of this thesis focuses on the idea of developing an efficient and controlled method of addition polymerization to synthesize high molecular polymers and exploring its potential application.Based on the above background and interest,we developed living additionpolymerization of cyclopropene for the first time.The prepared bidentate phosphine ligand palladium(II)catalyst was used to synthesize polymers with controlled molecular weight(M_n)and narrow molecular weight distribution(D)under mild conditions.Kinetic experiments show that the polymerization process can be quickly initiated and the controlled chain growth was then followed.Different block copolymers were prepared through chain extension experiments.In addition,we conducted a series of comparative experiments to study the polymerization mechanism,and proposed a mechanism for synergistically controlling the living polymerization process by monomers and catalysts.