Hydrogen-Induced Polymerization Of A Maleimide Structure Control And A Controlled Radical Polymer Sequence

Hydrogen bonding is the most widely used intermolecular weak interaction.Studies have shown that hydrogen bonding plays a crucial role in controlling the polymerization process and the properties of polymers.Fluoroalchol is a kind of strong polar solvent with large volume.It can form hydrogen bondings with some monomers,which affect the activity of monomer and the behavior of homopolymerization or copolymerization.N-substituted maleimide are typical hypoxic monomers with ?,?-unsaturated double bonds,which can be homopolymerized and copolymerized with a variety of electron-rich monomers.Studies have shown that fluoroalcohols can form hydrogen bonds with N-substituted maleimides.This thesis is mainly about the impact of the hydrogen bonding toward the homopolymerization and copolymerization of N-propylmaleimide based on the work of our group's previous work,including the controlled free radical polymerization of monomers such as 4-vinylpyridine,2-vinylpyridine and N-pyrrolidone,and the preparation of copolymer with defined sequence induced by hydrogen bonding effect,the specific work include:(1)Controlled free radical polymerization of N-propylmaleimide basing hydrogen bonding between fluoroalcohol and N-propylmaleimide(MI).The homopolymerization of maleimide monomers have been reported by free radical polymerization,resulting in polymers with lower molecular weight and wide molecular weight distribution.In this work,we first combined the xanthate(EXEP)as the chain transfer agent and hexafluoroisopropanol(HFIP)as the solvent to realize the controlled polymerization of MI.The molecular weight of the polymer can reach 3×104 g/mol.As a comparison,the molecular weight of the polymer was only 1.5×104 g/mol and the molecular weight distribution was wider when using 1,4-dioxane as solvent.The thermal characteristic of the polymers with similar molecular weights obtained from different solvent was studied by DSC under a nitrogen atmosphere.It turned out that the Tg of polymer obtained from fluoroalcohol as solvent was higher than that from 1,4-dioxane.(2)Further,the differences between the copolymerization of MI and VAc respectively using HFIP and 1,4-dioxane as solvent in kinetic behavior,copolymer composition,polymer sequence and copolymer thermal characteristic were investigated.When using HFIP as solvent,the copolymerization controllability over MI and VAc was better than that using 1,4-dioxane as solvent,and the reactivity of VAc was obviously improved resulting copolymers with higher VAc contents and lower Tg.When the feed ratio of [MI]0/[VAc]0 was 200/300 using HFIP as solvent,alternative copolymer was obtained.The effect of the two solvents on the copolymerization of MI and VAc at different temperatures was investigated in this work because of the significant effect of temperature on the hydrogen bonding.The results showed that the sequences controlled copolymers of MI and VAc could be obtained by changing the feed ratio,the solvent and the polymerization temperature.At the same time,the effect of hydrogen bonding toward reactivity of monomers was further testified by computer simulation,which enriched the research of hydrogen bonding induced controlled radical polymerization.