Synthesis Of Bio-Based Polyesters And Poly(Ester Amide)s And Their Applications In Controlled Pesticide Release

Motivated by the general concern of circular economy and environmental protection,the research of renewable polymers has developed rapidly in recent years.Furan-based polymer have been the hotspots in this field and various aliphatic or aromatic polyesters and poly(ester amide)s were synthesized.In this dissertation,A series of aliphatic polyesters and poly(ester amide)s were prepared by condensation polymerization,ring-opening polymerization and acyclic diene metathesis polymerization.The structure-property relationship of bio-based polymers is systematically studied.And the nano-capsules were successfully prepared which achieved the sustained-release of the Thiophanate-Methyl.(1)A cyclic monomer containing furan units was synthesized.Furan-based polyesters are obtained in high molecular weights by entropy-driven ring-opening polymerization and the relationship between the position of ester bond on the thermal properties and crystallization behavior of the polyester was investigated.2,5-furandicarboxylic acid and 1,12-dodecanediol were arranged into the cyclic monomer at low concentration.And furan-based polyester was prepared by entropy-driven ring-opening polymerization.The products are white which indicates that the synthetic process effectively avoids the colouring problem commonly existing in polycondensation.The transesterification reaction does not affect the chain structure but causes a broader molecular weight distribution.Compared with the polycondensation of 2,5-furandimethanol and 1,12-dodecanedioic acid,the products have better thermal stability and higher melting points by ring-opening polymerization.(2)A diene monomer containing furan units was prepareded by an efficient esterification reaction.A furan-based aliphatic polyester was synthesized by acyclic diene metathesis polymerization and the effects of the density of furan and ester bond on the thermal properties,crystallization and degradation behavior of polyesters was investigated.A diene monomer was synthesized by the esterification reaction of 2,5-furandimethanol with 10-undecenoyl chloride and which was homopolymerized and copolymerized with 1,9-decadiene.Furan-based polyesters are obtained by hydrogenation reduction.The results show that increasing the density of the furan units is beneficial to improving the thermal stability and melting point of the polyester.Increasing the content of ester bond facilitates polymer degradation and improving the feed ratio of 1,9-decadiene results in a decrease in the molecular weights and poor solubility.(3)A new method for preparing periodic sequence aliphatic poly(ester amide)s was established.The effects of the structure of poly(ester amide)s on its thermal properties,crystallinity,surface wettability,and degradation profiles were studied.Inspired by segmer assembly polymerization,glycolic acid and lactic acid units were arranged into cyclic monomers using ring expansion reactions.Poly(ester amide)s with the alternating sequence structures of glycolic acid and 7-aminoheptanoic acid,lactic acid and 7-aminoheptanoic acid and their random copolymer were prepared by entropy-driven ring-opening polymerization.The products are amorphous state due to the side groups of the lactic acid units disrupt the regular packing of the poly(lactic acid-alt-7-aminoheptanoic acid)chain.While poly(glycolic acid-alt-7-aminoheptanoic acid)have good crystallinity.In addition,all the poly(ester amide)s are hydrophobic and have good hydrolysis performance under basic conditions.(4)The bio-based aliphatic polyester and poly(ester amide)s nano-microcapsules encapsulation with Thiophanate-Methyl were prepared.The effects of polymer structure and microcapsule size on the sustained-release behavior were investiged.The bio-based polyester and PEAs nano-microcapsules encapsulation with Thiophanate-Methyl were prepared by emulsion solvent volatilization.The sustained-release of nanoparticles under neutral conditions was studied within 200 h.The results show that the release of Thiophanate-Methyl could remain for more than 200 h.Within a certain range,the increase in nanoparticle size and introduction of hydrophilic groups in polymer chains are conducive to the release of Thiophanate-Methyl.