Study On Polymerization Of Lactide/Alkene Polar Monomer Initiated By Lewis Pairs

Lactide is a natural environmentally friendly and harmless material.It has broad prospects in the field of medical materials,agricultural materials and daily necessities.At the same time,the product itself has some defects of polylactide mechanical properties.The existing methods are mostly modified by blending with polar polar monomers,carbon fibers and inorganic nanoparticles.Although its mechanical properties have been enhanced,there are problems such as uneven dispersion and easy agglomeration.Lewis pairs has attracted much attention in recent years because of its good reaction effect in the catalytic polymerization of polar monomers and cyclic ester monomers.This paper is the starting point of this paper.For the first time,the copolymerization of lactide and polar monomer was carried out in Lewis pairs.The polylactide was polylized from the synthetic point of view.From the above two aspects,the following content is studied in this paper:?1?The polymerization of Lewis pairs to the catalytic lactide monomer.The results of different polymerization of Lewis acids and bases were compared.It was found that Lewis acid and alkali could effectively initiate lactide ring opening polymerization under the condition of large steric hindrance and moderate acid base.Among them,DMAP/Zn?CH₂CH₃?₂ Lewis pairs can produce 98%poly lactide products in 10min,and the product is ring structure.The acid-base and group resistance of Lewis acid/base will affect the reaction effect.?2?Try Lewis pairs to initiate homopolymerization of polar monomers MMA,MA and AN.In this system,the Lewis acid base system with better activity should be the best system of acid-base and steric hindrance.It is found that the activity of polymerization is also increasing with the increase of monomer polarity.Among them,the yield of acrylonitrile initiated by DBU/Zn?CH₂CH₃?₂ Lewis pairs is 78%.In terms of Lewis pair,A1 Lewis acid plays an effective catalytic role in the polymerization of polar monomers.?3?Through the results of the above two parts,the copolymerization of lactide and different polar monomers is attempted and the specific structure of the product is studied.The possibility of a polar monomer polymerization initiated by the active center of the poly?polypropylene?,the polymerization of lactide initiated by the polar monomer active center and the two monomer random initiating polymerization are discussed.It was found that only the acrylonitrile,a strong polar monomer active center,initiated the structural characteristics of the two copolymers in the polymerization product of lactide.The polymer was acrylonitrile and lactide block copolymer,The specific composition is AN mass fraction 68.8%,LA mass fraction 31.2%.Thus for the first time the modification to the polymerization of polarity of polylactide.