Synthesis And Application Of Precision Fluorenecontaining Polymers Based On Diverse Reactions Of Maleimide Group

The monodisperse polymers with precision construtions are an ideal sample for accurately studying on the relationship between structure and properties of polymers.It is a great theoretical and practical value that synthesize the monodisperse polymer with the definite construction and contained functional group,through the diverse reactions based on maleimide group.The main contents of this paper are as follows:(1)Based on the diversity of maleimide reaction,the monodisperse and the definite topology polymers are constructed.(2)The synthesis process of function contained polymer was established by in-situ quantitative monitoring,fluorescence work curves are established by using monodisperse linear-polymer,and then step polymerization and synthesis process of polymer cyclizition are monitoring by the work curve.The specific work is as follows:(1)Maleimide is a functional group which can undergo diverse reactions,such as DielsAlder cycloaddition reaction,retro Diels-Alder reaction,Michael addition reaction,Huisgen cycloaddition reaction,etc.Meanwhile,many "click" reactions on maleimide are usually more moderate and efficient,and the maleimide group is relatively stable,these advantages are highly desirable for polymer synthesis and topology construction.In this work,five monodisperse polymers with degree of polymerization(DP)of 2,4,8,12,16 were synthesized by the iterative exponential growth strategy based on orthogonal deprotections and thiol-malaimide Michael addition.Some precision cyclic polymers(DP = 2,4,8)were constructed from the respective linear precursor by intramolecular end-to-end thiol-Michael addition.(2)Secondly,step-growth polymerization of the maleimide-fluorene-thiol monomer progressively consumed the maleimide group during polymer chain propagation and led to a gradual increase of fluorescence.This provides a quantitative and robust approach to monitor polymerization process in situ.Moreover,cyclic oligomers were produced via intramolecular thiol-maleimide Michael addition in highly diluted solution of linear precursors,and the cyclization process resulted in gradual enhancements of fluorescence intensity due to the elimination of maleimide groups.The cyclic oligomer content at determined time can thus be quantitatively calculated based on fluorescence emission,enabling a real-time approach for monitoring/surveilling the cyclization process.We further applied this fluorogenic probe method to quantitatively monitor the formation of polymers with more complicated topologies,such as “cyclic-brush-like” macromolecules.This work demonstrates a facile,robust,and versatile platform for monitoring polymerization process in situ,which may inspire and facilitate diverse molecular design and preparation in the field of precision polymer synthesis.