Design,Synthesis And Self-assembly Behaviors Of Environmentally Responsive Photoelectric Functional Polymers Based On Single Electron Transfer-living Radical Polymerization

Single electron transfer-living free radical polymerization(SET-LRP)is a new type of polymerization method developed on the basis of the atom transfer radical polymerization(ATRP).In SET-LRP,Cu(0)result in the cleavage of carbon-halogen bond of the initiator in a multiphase solution through the heterogeneous outer-sphere electron transfer for the generation of free radicals to activate dormant species and then the formation of passivation-activation balance to control the concentration of free radicals to achieve controllable "free radical polymerization".It has been known as a better excellent method to control the molecular weight of the polymer,the molecular weight distribution,chemical composition as well as synthesis of the complex topology-varied polymers and functional polymers with high chain-end functional group content.In this thesis paper,we mainly prepared a series of polymer photoelectric materials by using SET-LRP polymerization technique and ATRP.The effects of different experimental conditions on the polymerization kinetics and photoelectric properties of the obtained molecules were studied in detail.First,we used the polymerization kinetics of methyl acrylate(MA)in dimethyl sulfoxide at room temperature as the research object.By adding different molar concentrations of anhydrous FeCl3 to the reaction,we studied the effects of different molar stoichiometry of anhydrous FeCl3 on the polymerization kinetics of MA in detail.The experimental results indicate that the anhydrous ferric chloride has important influence on the kinetic polymerization of MA.After addition of different amounts of anhydrous ferric chloride,the reactions still showed a living radical polymerization in nature,the initiator efficiency was relatively high and the chain-end functional groups also had more perfect retention and were more than 85%.Additionally,after the addition of iron salts,the polydispersity index of polymer became increased(1.19-1.24),but still similar with those without addition of the ferric salts,the addition of Fe(III)has little effect on the molecular weight distribution of the polymer.Meanwhile,with the amount of Fe(III)salt increased,the apparent rate constant linear continued to decline which finally led to the induction period prolonged.It is shown that the ferric ions are involved in the polymerization kinetics of SET-LRP,and its function is very different from that of divalent copper under the same experimental conditions.The results show that the addition of FeCl3 with deactivation can significantly change the polymerization kinetics of SET-LRP.Poly(N-isopropylacrylamide)(PNIPAM)is an amphiphilic thermosensitive polymer with the hydrophilic amide group and the hydrophobic isopropyl group in the main chain.A reversible phase change occurs due to the intermolecular interaction with the change of the outside temperature.Therefore,we use tetraphenylethene derivatives as initiators,which have the advantages of easy-to-synthesize,highly efficient chemical modification feasibility and high quantum yield.A high molecular weight polymer PNIPAM-Br with AIE characteristic was prepared by polymerization of N-isopropylacryla-mide through SET-LRP.Then the monomer of styrene was used as comonomer to convert the active PNIPAM initiators to an amphiphilic block polymer PNIPAM-PSt,and the photophysical properties of initiators and amphiphilic block polymer at different temperatures and concentrations were studied in detail.It was found that the fluorescence intensity of AIE-active initiators decreased with the increase of temperature at the same concentration of solution,while the fluorescence intensity of the block polymer increased firstly,and then decreased after the temperature exceeded 37 oC.Under the same conditions,by changing the concentrations of AIE-active initiatorst and block polymer in the mixed solvents of tetrahydrofuran and water,we found that the fluorescence intensity of AIE effect initiator decreased with the decrease of concentration,while the change tendency of fluorescence intensity for block polymer was similar as those obtained from the temperature changes.Finally,we further studied the self-assembly behaviors of amphiphilic block polymers at different concentrations.It was illustrated that it was a feasible to investage the comdensed state change of block polymer by grafting the AIE active moieties to the terminal of amphiphilic polymer.