Stimuli-Responsive Luminescent Liquid Crystalline Polymers: Design,Synthesis,Phase Structure,Photophysics Property And Application

This thesis focuses on the construction of stimuli-responsive luminescent liquid crystalline polymers(LLCPs)and multi-band polarized light-emitting materials.We employ the hydrogen bonding strategy to build several kinds of stimuli-responsive LLCPs with different main chain and AIE side chains.Further,we fabricate a bands-adjustable multicolor polarized luminescence material combining stimuli-responsive properties and the linearly polarized luminescence.(1)A series of LLCPs PPA(PTC₄)_x with different molar ratios of(4,4'-dibutanoxy tetraphenylethylene)-1-pyridine(PTC₄)to poly(2-vinylterephthalic acid)(PPA)is successfully synthesize via hydrogen bonding.The phase structure and luminescent behaviors of PPA(PTC₄)_x are strongly dependent on the content of PTC₄ in the side chain of the complex.With decreasing x,PPA(PTC₄)_x undergo a phase structure change from smectic(Sm)(x?0.8)to columnar nematic phase(0.6?x?0.05),and to the amorphous state(x=0.025).Moreover,PPA(PTC₄)_x exhibite typical AIE behavior with tunable colors,with the emission peak at 510 nm(x=1.0)gradually red-shift to 551nm(x=0.025).Furthermore,PPA(PTC₄)_x show reversible fluorescence switching under the phenol vapor owing to the protonation effect of PTC₄.(2)PVA(PTC₄)_xwith different molar ratios of PTC₄to poly(vinyl alcohol)(PVA)is successfully synthesize via hydrogen bonding.The stiffness,flexibility and acidity of the main chain have important influence on the formation of the LC phase,luminescent and stimuli-responsive behaviors of PVA(PTC₄)_x.PVA(PTC₄)_xform a Sm phase structure with the x?0.6.All the polymers exhibit typical AIE behavior with yellow-green emission at 510 nm.Owing to the protonation effect of pyridine group in PTC₄,PVA(PTC₄)_xshow multicolor luminescence switch under the different acid vapors.Moreover,because of the existence of the hydrogen bonds,PVA(PTC₄)_1.0 shows a reversible,spontaneous fluorescence switch under the acid vapor with p Ka(27)5.25.If the sample is fume with the acid vapor having p Ka(27)5.25,PVA(PTC₄)_1.0 not only exhibits a lager luminescence red shift but cannot recover unless the sample is treating with the triethylamine vapor.Furthermore,a simple sensor,intelligent emission system,and a rewritable paper with tunable multicolor emission and high contrast is prepare based on the fluorescence response and recovery behavior,which may be applied in optical memory system.(3)PPA(BPCN)_xwith different molar ratios of?-cyanostilbene derivatives(BPCN)to PPA is successfully synthesize via hydrogen bonding.With decreasing x,PPA(BPCN)_xform a Sm phase(x=1.0,0.7)and columnar nematic phase(x=0.4,0.1),respectively.PPA(BPCN)_xalso show AIE behavior.Moreover,PPA(BPCN)_x show a regular emission red shift,from 508 nm(x=1.0)to 521 nm(x=0.1),which attribute to the increase of the reorganization energy and the decrease of the number of hydrogen bonds in PPA(BPCN)_x with x decreasing.PPA(BPCN)_xexhibit a similar acid stimuli-responsive behavior with PPA(PTC₄)_x.Moreover,mixing the PPA(BPCN)_x with 4-cyano-4'-n-pentylbiphenyl(5CB),we obtain a device with linearly polarized emission behavior,and the mixture is orientated in the antiparallel LC cell.(4)Combine the above stimuli-responsive mechanism,a stimuli-responsive luminescent molecule,(Z)-4'-(1-cyano-2-(4'-pyridinephenyl-4-yl)vinyl)phenyl-4-hexyloxy methacrylate(M6BP)with a D-A structure and based on?-cyanostilbene is successfully synthesize.M6BP exhibit solid state emission behavior and high solid-state high quantum yield((37)_F).After introducing the appropriate crosslinking agent,we fabricate the free-standing film with linearly polarized luminescence and stimuli-responsive property via photo polymerization the uniaxial orientation of M6BP.The free-standing film show a maximum emission at 526 nm.Meanwhile,the free-standing film exhibit good dichroism with the dichroic ratio and polarization ratio is measure as2.63 and 0.45,respectively.Furthermore,the free-standing film show a reversible linear polarized fluorescence switching(526 nm to 550 nm)under the acid/base vapor,which is attribute to the protonation and deprotonation of pyridine groups on the M6BP.