Preparation Of Hyperbranched Multi-Arm Divinylbenzene-Methacrylic Acid Copolymer And Its Self-Assembly In Selective Solvent

In recent years,the hyperbranched polymer has been a hot topic in study of polymer science..Especially in the synthesis and self-assembly of hyperbranched polymer,people had made great progress.But there are still some problems.For example,the kind of hyperbranched polymer used for self-assembly is limited, the synthetic methods should be improved and so on.Therefore,how to further expand and enrich the type of hyperbranched polymer,giving more fentures to monomers,reveal the structure of the polymer and self-assembled morphology,is vrey important. In this thesis,an core-shell-structured amphiphilic hyperbranched multi-arm copolymer were prepared by using reverse iodine transfer polymerization(RITP) and atom transfer radical polymerization(ATRP) as well as its self-assembly behaviors in selective solvents.The works can be summarized as follows:(1)Hyperbranched polydivinylbenzene(PDVB-I) having iodine end groups was synthesized from divinylbenzene(DVB) by reverse iodine transfer polymerization(RITP) in the presence of iodine with azobisisobutyronitrile(AIBN) as initiator.The molecular weight distribution of the product were characterized by gel permeation chromatography(SEC) analysis,the structure of the polymer were characterized by NMR resonance instrument(1HNMR) and infrared spectroscopy.The effects of reaction temperature, the ratio of raw materials and the kinetic behavior of the polymer were investigated on the polymerization reaction.The polymerization time became longer with the increase of the iodine content.We can control the polymerization rate by changing the the iodine content.The molecular weight of the polymer was added with the increase of the polymerization time and reached11234g/mol by the end of the final polymerization.The molecular weight distribution was narrowed with the increase of the conversion rate and the value generally fluctuated between 1.1 to 1.6.By the end of the final polymerization,the degree of branching of PDVB-I is 0.48,which fully demonstrated the characteristics of a living polymerization.(2) Initiated ATRP,using PDVB-I as macroinitiator, methyl methacrylate(MMA)as a monomer,copper bromide(Cu Br2) and cuprous bromide(Cu Br) as catalyst,pentamethyl diethylenetriamine(PMDETA) as ligand,toluene as a solvent,have been successfully used to prepare hyperbranched multi-arm divinylbenzene-methyl methacrylate copolymer(PDVB-co-PMMA),then converting it to amphiphilic hyperbranched multi-arm copolymer(PDVB-co-PMAA) by hydrolyzing.The molecular weight distribution of the product were characterized by gel permeation chromatography(SEC) analysis to explore the effect of the ratio of MAA to PDVB-I and the molecular weigh of PDVB-I on the polymerization.when the ratio of MMA and PDVB-I from 50:1 to 100:1,the gel point of the polymerization appeared later,the rate of MMA became slower,the the molecular weigh of product became larger and increased from 14800g/mol to 20500g/mol.When the feed ratio is the same,the conversation of MMA and the the molecular weigh of product increased with the the the molecular weigh of PDVB-I and increased from 14800g/mol to15900g/mol.The structure of the polymer were characterized by NMR resonance instrument(1HNMR) and infrared spectroscopy.The results showed that we had synthesized the PDVB-co-PMAA.Hydrophobic core and hydrophilic polymer arms provide important basis for the self-assembly behavior in different solvents.(3)A series of amphiphilic hyperbranched multi-arm copolymer with a hydrophobic DB-variable hyperranched PDVB-I core at different polymerization temperature was synthesized by ATRP. Different block ratio of the polymer was synthesized by controlling the monomer feed ratio.and then researching the influence of the different block ratio and the degree of branching on the self-assembly behavior of polymers in the DMF and water. The results show that the particle size of the micelles is reduced with the increase of the agitation time,and the size distribution fluctuation between 0.123 and 0.145.Different block ratio of PDVB-co-PMAA with the same degree of branching have different morphology of the self-assembly objects.The size of the micelle decreased with the increase of the proportion of the hydrophilic PMAA short arms, eventually leading to transfer from the spherical micelles having a obvious core-shell structure to unobvious core-shell structure.Themorphology of the self-assembly objects transfer from vesicles to rodlike micelle,to the spherical micelles with the decline in the degree of branching PDVB-I core.On one hand,micelles formed by self-assembly has important research value in theory,on the other hand,it has an extensive application prospect on nano-materials, separation membranes, biomaterials, surface active agents.The relationship between molecular structure and morphology of the self-assembly of this study is not only an important research value in theory,but also in the nano-materials,separation membranes,biomaterials,surface active agents,which have an extensive application prospect.