Study On Synthesis Of New Structure Bottlebrush Polymer By Ring-opening Metahesis Polymerization

Bottlebrush polymer is a kind of branched polymer or graft polymer.The retention time of this polymer in vivo is longer than that of linear polymer.So the bottlebrush polymer has a good application in drug loading.This paper is based on methoxypolyethylene glycols(mPEG)which has good biocompatibility material.A polymerizable macromonomer with good hydrophilicity and a polymerizable macromonomer loaded with magnetic materials were designed.Three different types of nano bottlebrush polymers were synthesized by Ring-Opening Metathesis Polymerization(ROMP)using these two macromonomers.First,5-norbornene-2,3-dicarboxylic anhydride was reacted with 6-amino-1-hexanol to make the product contain hydroxyl group.Bromine can be introduced into mPEG by esterification of mPEG and 2-bromoisobutyryl bromide with molecular weight of 5000,and then azide can be used to replace bromine to make the reaction product contain azide group.Azide and alkynyl groups were cyclized by click reaction to form a macromolecular monomer whose main component was mPEG.The structures of the products were confirmed by FT-IR and 1H-NMR.2000 molecular weight mPEG was used to react with 2-bromoisobutyl bromide,and the reaction product was used as initiator and tert butyl acrylate to carry out Atom Transfer Radical Polymerization(ATRP).Three different molecular weight two block polymers(mPEG-PtBA-Br)were prepared,and the polydispersity index of three polymers was tested by gel permeation chromatography,all of which were less than 1.1.The diblock polymer containing azide group(mPEG-PtBA-N3)was prepared by replacing bromine in the three polymers with azide.Two kinds of mPEG-PtBA-N3 with smaller molecular weight were used to generate two kinds of loadable magnetic materials macromonomers(mPEG-PtBA-Norb)with different molecular weight.The structures of all the reaction products were verified by FT-IR and 1H-NMR.Finally,three different bottlebrush polymers were synthesized by ROMP using two different macromonomers separately and alternately.Three kinds of bottlebrush polymers were characterized by 1H-NMR,gel permeation chromatography,transmission electron microscopy and dynamic light scattering.The diameter of the three types of bottle brush polymers is less than 50 nm,and the morphology is close to worm shape.It is expected that the three types of bottlebrush polymers will play a practical role in drug delivery and efficient catalysis on a more subtle scale.