The Design,Synthesis And Application Of Conjugated Polymer-Based Multi-Arm Star-Like Block Copolymers

Conjugated polymers(CPs) have received extensive attention due to important applications in organic optoelectronic,light-emitting diodes(LEDs),thin film transistors and biosensors.Among various types of conjugated polymers,poly(3-alkylthiophene)(P3AT),a p-type organic semiconductor,is the most widely studied organic semiconductor due to its excellent solution processability,environmental stability,high carrier mobility and good electrochemical properties.P3HT can be used to prepare polymer films and organic-inorganic hybrid materials,which have been widely applied in the field of materials.In this thesis,a series of multi-arm star-like block copolymers poly(tert-butyl acrylate)-b-poly(3-hexylthiophene)(PtBA-b-P3HT)and amphiphilic star-like block copolymers poly(acrylic acid)-b-poly(3-hexylthiophene)(PAA-b-P3HT)based on p?cyclodextrin were prepared by atom transfer radical polymerization(ATRP),grignard metathesis method(GRIM)and "click" chemistry.LB self-assembly behavior and photoluminescence performance of star-like block copolymers(PtBA-b-P3HT)were studied.The unimolecular micelles formed in solution of star-like block copolymer PAA-b-P3HT were used as nanoreactors to prepare organic-inorganic nanocomposites P3HT-CdSe.(1)Synthesis of multi-arm star-like block copolymers PtBA-b-P3HT and PAA-b-P3HTA series of multi-arm star-like block copolymers PtBA-b-P3HT with different molecular weights and well-defined architectures were synthesized by ATRP,GRIM and "click" chemistry.Hydrolysis of the tert-butyl group on the PtBA block with trifluoroacetic acid to obtain the amphiphilic star-like block copolymers PAA-b-P3HT.They were characterized via 1H-NMR,FT-IR and GPC.The results showed that poly(tert-butyl acrylate)(PtBA)with different molecular weight could be obtained by controlling the reaction time of ATRP process.Finally,a series of block copolymers with narrow weight distribution(PDI<1.2)were obtained after the hydrolysis of PtBA blocks into PAA blocks.(2)LB self-assembly of multi-arm star-like block copolymers PtBA-b-P3HTThe star-like block copolymers PtBA-b-P3HT can easily form a network morphology by self-assembly at the air/water interface.The patterns enhanced the photoluminescence(PL)efficiency due to successfully transferring highly efficient disordered conjugated polymer chains from solution into solid state.The morphological evolution under surface pressure were observed by AFM and TEM.A new model has been proposed to illustrate the mechanism for the formation of network structure.(3)Fabrication of organic-inorganic nanocomposites P3HT-CdSe using star-like block copolymers as nanoreactorsThe unimolecular micelles were prepared by using the amphiphilic star-like block copolymers(PAA-b-P3HT).Then the unimolecular micelles were also used as nanoreactors to fabrication uniform P3HT-capped cadmium selenide(CdSe)quantum dots(QDs)via the strong coordination interaction between carboxyl groups of PAA blocks of star-like PAA-b-P3HT and the metal moieties of precursors(Cd(acac)2 and NaHSe).The unimolecular micelles and organic-inorganic nanocomposites P3HT-CdSe were characterized by AFM,TEM,XRD,EDS and absorption spectroscopy.The results show that the sizes of the prepared CdSe nanoparticles are uniform with the molecular weight of the PAA blocks chain increasing,the diameters of the obtained CdSe nanoparticles increase.As the inner PAA blocks are covalently connected to the outer P3HT blocks,the conjugated polymer P3HT chains are intimately and permanently tethered on the surface of CdSe nanoparticles.