Synthesis Of Graft Copolymer From Aliphatic Polyester

Polyester is one of the most widely applied oxygenated polymers in daily life,and has broad application prospects in agriculture,medicine and industry,etc.Among them,due to the good biodegradability and biocompatibility of the aliphatic polyester material and widely studied,now has developed a large number of synthetic aliphatic polyester pathway,The ring-opening copolymerization of cyclic anhydrides with epoxides provides a simple and efficient method,but synthetic aliphatic polyester shows low molecular weight,monotonic properties and other undesirable factors.With the rapid development of social demand,the performance requirements for aliphatic polyester is increasing,so the functional development based on aliphatic polyester materials is an important part of its application development.Graft modification is a commonly used polymer modification method,can choose different properties of the monomer as a graft monomer,in order to improve the properties of polymer,such as lubricity,hydrophobicity and biocompatibility,so this paper uses graft copolymerization to modify the aliphatic polyester.Because polyolefin has excellent chemical and physical properties,as well as low cost,good recyclability and simple processing capacity,Therefore,copolymerization of grafted vinyl monomers is one of the effective ways to modify aliphatic polyester.This paper uses the method of post-polymer modification to select the aliphatic polyester P(SA/ECH)synthesized by succinic anhydride(SA)and epichlorohydrin(ECH)for graft polymerization modification.In the graft polymerization,it is mainly based on the breakage of the C-Cl bond in the ECH unit in P(SA/ECH)to form an active site and initiate the graft polymerization of the olefinic monomer.The work of this thesis includes three parts: first,ZnGA is used to catalyze the graft copolymerization of P(SA/ECH)with styrene(St)and N-vinylpyrrolidone(NVP).Furthernore,in order to optimize the graft polymerization process,ZnGA catalytic SA,ECH and NVP graft polymerization experiments are carried out using one-pot polymerization.Secondly,using the nitroxide-mediated radical polymerization(NMRP),by introducing TEMPO on P(SA/ECH),a macroinitiator is formed,and then grafting polystyrene(PS).Finally,the reaction conditions and results of photocatalysis initiated by grafting poly(methyl methacrylate)(PMMA)on P(SA/ECH)were investigated.1.To investigate the graft copolymerization by ZnGA catalytic P(SA/ECH)and styrene(St),N-vinylpyrrolidone(NVP)monomers.The research results show that the reaction times and feed ratios can effectively control the grafting of the side chain.Furthernore,in order to optimize the graft polymerization process,the one-pot graft copolymerization of three monomers SA,ECH and NVP catalyzed by ZnGA was investigated.Structural characterization of all grafting polymers was carried out,and the experimental results showed that the grafting polymerization of aliphatic polyester could be carried out by one-pot method.Grafting poly(N-vinylpyrrolidone)can effectively improve the hydrophilic performance of P(SA/ECH).2.the copolymerization of P(SA/ECH)grafted poly(styrene)(PS)was achieved by nitroxide-mediated radical polymerization(NMRP)method.First,the reaction between P(SA/ECH)and TEMPO was investigated to determine the reaction conditions of ZnGA catalyzing the formation of macromolecular initiator P(SA/ECH)-TEMPO.P(SA/ECH)-TEMPO can be prepared by both one-step and one-pot method.The experimental results show that the reaction is 15 h at n(SA): n(ECH): n(TEMPO)= 8:8:1,120 ?,the best effect was obtained by P(SA/ECH)-TEMPO with TEMPO grafting rate of 4.4 %.Then P(SA/ECH)-TEMPO was used to realize the graft copolymerization of poly(styrene),and the influence of different reaction times and feed ratios on the results of graft polymerization are also investigated.The results showed that P(SA/ECH)grafted poly(styrene)was successfully achieved.Structural characterization of the obtained graft polymer,and testing the thermal properties of the graft copolymer.Comparing P(SA/ECH)and found an increase in thermal stability of graft polymer P(SA/ECH)-g-PS.3.The metal-free photocatalytic system was used to initiate the copolymerization of P(SA/ECH)grafted poly(methyl methacrylate)(PMMA).In ensure metal-free preparation,synthetic aliphatic polyester P(SA/ECH)uses [DBU][Pac] as a catalyst.Then,perylene is used as metal-free photocatalyst to carry out photocatalytic grafting of poly(methyl methacrylate).The effect of the catalyst concentration on the grafting copolymerization reaction were studied,and the control of the "on" / "off" graft polymerization of light was realized.The polymerization results show the reliability of the switchable control of photocatalytic polymerization.For the further development of metal-free catalytic generation of functional aliphatic polyester provides an experimental basis.