| In this thesis, a series of linear π-conjugated main-chain polymers with similarstructures, including polyfluorene, polysilafluorene, polycarbazole, and hyperbranchedpolyfluorenes, were successfully prepared by Suzuki polycondensation (SPC) reaction. Thechiral supramolecular assembly of achiral π-conjugated main-chain polymers was achievedin mixed tersolvents system (CHCl3/(R)-(+)-limonene,1R or (S)-(-)-limonene,1S)/poorsolvent) employimg chiral limonene (1R or1S) as chiral solvent. The effects of polymerstructures, types of poor solvents, the volume ratio of chiral solvent and poor solvent, theenantiopurity of limonene and the concentration of polymer repeating unit on chiralsupramolecular assembly behavior of achiral π-conjugated main-chain polymers wereinvestigated. The author thinks that this thesis is devoted to the following two points:(1) Inthe linear π-conjugated main-chain polymer system, we discovered that polymer structurehad a obvious influence on chiral assembly of above polymers in the mixed tersolvents.Under the same experimental conditions, chiroptical inversion was observed betweenpolyfluorene and polysilafluorene, however, chiral assembly of polycarbazole could not beproceeded.(2) In the hyperbranched polyfluorene system, the chiral assembly behavior ofpolymer was mainly affected by the content of branching unit in polymer structure. Thechiral signal of polymer aggregates disappeared when the content of branching unitsexceeded7.5%.The main research contents of this thesis are summarized as follows:(1) A series of linear π-conjugated main-chain polymers with similar structures,including homopolymers poly(9,9-di-n-octylfluorenyl-2,7-diyl)(PF8),poly(9,9-di-n-octylsilafluorenyl-2,7-diyl)(PSi8),poly(9-(1-octylnonyl)-9H-carbazole-2,7-diyl)(PCz8), alternating copolymers P(F8-alt-Si8),P(F8-alt-Cz8), and P(Si8-alt-Cz8) and random copolymer P(F80.80-ran-Si80.20) wereprepared by Suzuki polycondensation (SPC) reaction. The polymer structure wascharacterized by gel permeation chromatography (GPC), nuclear magnetic resonance(NMR) and elemental analysis (EA). The effects of the polymer structure, the types of poor solvent, the volume ratio of poor solvent and chiral solvent, the enantiopurity of limoneneand the concentration of polymer repeating units on chiral supramolecular assemblybehavior of above polymers in mixed tersolvents system (CHCl3/(1R or1S)/poor solvent)employimg chiral limonene (1R or1S) as chiral solvent were investigated. The mainresearch results are summarized as follows. I) Under the same experimental conditions,PF8, PSi8, P(F8-alt-Si8) and PF80.80-ran-Si80.20) aggregates all showed relatively strongchiral signals, however, no any chiral signal was detected in cases of PCz8、P(F8-alt-Cz8)and P(Si8-alt-Cz8) aggregates.(II) Under the same experimental conditions, PF8andP(F80.80-ran-Si80.20) aggregates gave very similar circular dichroism (CD) spectra, but CDintensity of PF8aggregates was much stronger than that of P(F80.80-ran-Si80.20) aggregates.P(F8-alt-Si8) and PSi8aggregates presented very similar CD spectra. The chiral inversionwas observed between PF8, P(F80.80-ran-Si80.20) aggregates and P(F8-alt-Si8), PSi8aggregates.(III) Among seven poor solvents employed, methanol (CH3OH) was the bestpoor solvent in current system. The absolute CD and gCDvalues of PF8and PSi8wereobtained when the volume ratio of CHCl3,(1R or1S) and CH3OH was0.3/1.2/1.5. ForP(F8-alt-Si8), the maximum of absolute CD and gCDvalues were given when the volumeratio of CHCl3,(1R or1S) and CH3OH was0.3/0.8/1.9.(IV) The CD intensities and gCDvalues of PF8, PSi8and P(F8-alt-Si8) aggregates all showed the linear dependence on therelative content of limonene enantiomers, rather than following the majority-rules.(V) TheCD intensities of PF8and PSi8increased linearly with the concentrations of repeatingunits, however, the CD intensity of P(F8-alt-Si8) increased firstly and decreased atrelatively higher concentration of repeating unit.(VI) Based on the Gaussian calculationresults, the chiroptical inversion between PF8and PSi8is attributable to the oppositeMulliken charges between Si in Si8and9-C in F8and between Cipsoin Si8and Cipsoin F8.The unsuccessfully chiral limonene-induced chiral assembly of Cz8-containing polymersmay be due to the relative stronger polarity of Cz8rings, which resulted in the weakinteraction between Cz8-containing polymer chain and chiral limonene.(2) A series of hyperbranched poly(9,9-di-n-octylfluorine)s (HPF8s), with differentcontents of branching unit (hexaoctyltruxene, HT), were successfully prepared by SPCreaction. GPC, NMR and EA techniques were used to characterize the polymer structures.The effects of the polymer structure, the types of poor solvent, the volume ratio of poorsolvent and chiral solvent, the enantiopurity of limonene and the concentration of polymer repeating units on chiral supramolecular assembly behavior of above polymers in mixedtersolvents system (CHCl3/(1R or1S)/poor solvent) employimg chiral limonene (1R or1S)as chiral solvent were investigated. The main research results are summarized as follows. I)Under the same experimental conditions, the CD intensities of HPF8s weakened graduallywith the increasing content of branching unit, when the content of branching units reached7.5%, the chiral signal disappeared.(II) Among seven poor solvents employed, methanol(CH3OH) was the best poor solvent in current system. The maximum of absolute CD andgCDvalues of HPF8-1were obtained when the volume ratio of CHCl3,(1R or1S) andCH3OH was0.3/0.8/1.9.(III) The CD intensity and gCDvalue of HPF8-1aggregatesshowed the linear dependence on the relative content of limonene enantiomers, rather thanfollowing the majority-rules.(IV) The CD intensities of PF8and PSi8increased linearlywith the concentrations of repeating units.(V) By analyzing the CD, UV-vis and FLspectra of HPF8s, the gradually weakened chiral signals of hyperbranched polymers maybe due to the relatively weakened interaction between HPF8s chain and limonene with theincreasing content of branching unit. |
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