Sequence-Controlled Polymerization Of Cyclic Ester Monomers Initiated By Aminotriphenolate Zirconium Complexes

The physical and chemical properties of copolymers can be affected by the sequence structure of monomers.Selective ring-opening copolymerization of cyclic ester monomers catalyzed by complexes is an important method for regulating the sequence structure of polymers.At present,the research on polymer sequence control still poses great challenges and is also one of the hotspots in polymer synthesis.Based on the above background,the main content of this article is to use metal zirconium complexes as initiators,combined with the inherent properties of different cyclic esters to design and synthesize polyhydroxycarboxylic acids with different sequence structures.Part 1: Introduce the research progress of selective polymerization of cyclic ester monomers.Part 2: The coordination space confinement effect of the amino triphenol zirconium complex with a large hindrance group was utilized to suppress the homopolymerization reaction of Benzyl O-carboxyanhydride(Phe OCA)monomers with large side groups.At the same time,the inhibition of cyclic ester monomer homopolymerization by carbon dioxide released by Phe OCA ring opening was utilized to achieve the alternating copolymerization reaction of Phe OCA and cyclic ester monomers with significant structural differences.This study introduces non chiral ester monomer glycolide(GA)into alternating polymerization to prepare polymers with ABB sequences α-Hydroxy acid.After the GA monomer was changed to methyl glycolide(Me G),the polymer with ABC sequence was successfully synthesized by regioselectivity ring-opening polymerization of the Me G.Part 3: In this chapter,zirconium complex of adamantine alkyl aminotriphenol was utilized to initiate the formation of lactide(LA)and β-Butyrolactone(β-BL)conducted polymerization reaction research.In preliminary work,we found that the homopolymerization of LA would inhibit the polymerization of β-BL when the tert butylaminotriol zirconium complex was used as the initiator.When the initiator changes to the zirconium complex of adamantine alkyl aminotriphenol,the reduction of the confined space leads to a reversal of the polymerization rate of the two monomers,achieving the copolymerization of the two monomers,LA units have isolated chemical environments in polymers.During the polymerization process,changing the chirality of LA monomers would not affect the sequence structure of the polymer.This indicates that the controlled polymerization system of the sequence does not rely on the stereoselectivity of the catalytic system.Finally,a summary of all the work during the master’s degree period was provided,and future development directions were proposed for the research topic of the paper.