- Thermostable birefringent copolyimide films based on azobenzene-containing pyrimidine diamines
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Azobenzene (azo)-containing polymers have attracted continuous attention due to their excellent photosensitivity. However, practical applications of their photo-induced birefringence have been hampered by low thermal stability. In this work, we report a s
- Tong, Faqin,Chen, Zhao,Lu, Xuemin,Lu, Qinghua
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p. 10375 - 10382
(2017/10/19)
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- Method for preparing polyimide polymer with azo-pyrimidine structure unit
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The invention relates to a method for preparing a diamine monomer with an azo-pyrimidine structure and a method for preparing a polyimide polymer by adopting the diamine monomer with the azo-pyrimidine structure. The preparation method comprises the following steps: carrying out a coupling reaction on 4-substituted aniline and sodium phenate to obtain 4-hydroxy-4'-substituted azobenzene; and carrying out nucleophilic substitution on the 4-hydroxy-4'-substituted azobenzene and dibromoalkane to generate bromo-azobenzene, and reacting the bromo-azobenzene with 4,6-diamido-2-mercaptopyrimidine to obtain the diamine monomer; and carrying out condensation polymerization on the diamine monomer with dianhydride to obtain polyimide. The pyrimidine structure is introduced into the diamine monomer, so that the charge transfer complex effect of aromatic rings of polyimide is reduced, and the glass transition temperature of the polyimide is reduced; and the azo group has photo-induced anisotropy, and an azo unit is introduced into the polyimide by alkyl chains having different lengths, so that the heterogeneous degree of the azo group can be effectively regulated, and the application of the polyimide in alignment films and other optical fields can be improved to a great extent.
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- Synthesis of diamine monomer with azo and polyimide prepared from diamine monomer
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The invention discloses synthesis of a diamine monomer with azo and polyimide prepared from the diamine monomer. The structural formula of the polyimide is shown in the specification. The polyimide is synthesized through polycondensation of the diamine mo
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- Anisotropic fluorescence emission of ionic complex induced by the orientation of azobenzene unit
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A series of azobenzene-containing fluorescent complexes with stilbene fluorescent unit were prepared based on the ionic self-assembly approach. The incorporation of the stilbene unit did not change the lamellar structure of the azobenzene-containing compl
- Wu, Jun,Lu, Xuemin,Yi, Zeyuan,Shan, Feng,Lu, Qinghua
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p. 3376 - 3383
(2013/07/28)
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- Synthesis, thermal stability and photoresponsive behaviors of azobenzene-tethered polyhedral oligomeric silsesquioxanes
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A series of azobenzene-tethered polyhedral oligomeric silsesquioxane (POSS) derivatives, i.e. monoazobenzene-substituted POSS (MonoAzo-POSS), bisazobenzene-substituted POSS (BisAzo-POSS) and triazobenzene-substituted POSS (TriAzo-POSS), were synthesized through the amidation acidylation of aminopropylisobutyl POSS and benzoic acid derivatives (AzoMs) with one, two and three azobenzene groups (AzoM1, AzoM2 and AzoM3). Their structures were characterized by FT-IR, 1H NMR, 13C NMR and mass spectra, and their thermal stability and photoresponsive behaviors in DMF solutions were evaluated with TGA, XRD and UV-vis spectra, respectively. The results indicated that the thermal stability and photoisomerization of azobenzenes could be effectively controlled by their molecular structure. In MonoAzo-POSS, the large steric hindrance of POSS destroys the molecular ordering and limits the molecular packing, contributing to its poor thermal stability. And the low molecular ordering of MonoAzo-POSS offers an azo group with large free space, and its trans-cis photoisomerization rate increases accordingly. But, in BisAzo-POSS and TriAzo-POSS, the incorporation of POSS units does not impact on the regularity of azobenzenes obviously, and the hindrance effect of nanosize POSS on the molecular motion plays a primary role in increasing their high thermal stability. Their photoisomerization rates decrease due to the steric hindrance of POSS and the unfolding structure of the azo moieties in BisAzo-POSS and TriAzo-POSS.
- Zhou, Jinlan,Zhao, Yongchen,Yu, Kaichao,Zhou, Xingping,Xie, Xiaolin
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p. 2781 - 2792
(2012/01/14)
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- Combined main-chain/side-chain liquid crystalline polymer with main-chain on the basis of "jacketing" effect and side-chain containing azobenzene groups
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Combining the concept of "flexible spacer" which can bring liquid crystalline (LC) properties to the side-chains and the side-group "jacketing" effect which can result in main-chain with rod-like conformation, we have synthesized a new combined main-chain
- Xie, He-Lou,Wang, Shao-Jie,Zhong, Guan-Qun,Liu, Yi-Xin,Zhang, Hai-Liang,Chen, Er-Qiang
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p. 7600 - 7609
(2012/07/28)
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- Thermal and photo alignment behavior of polymers in multiply-layered films composed of polyethylene imines having azobenzene side chain groups and polyvinyl alcohol
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Polyethylene imines having 4-methoxyazobenezene group through methylene spacer groups (PEI6M) were synthesized and their photochemical, thermooptical as well as photoorientational behavior were investigated. PEI6M films showed high dichroism and order par
- Kamruzzaman, Mohammad,Ogata, Tomonari,Kuwahara, Yutaka,Ujiie, Seiji,Kurihara, Seiji
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scheme or table
p. 32 - 41
(2012/01/06)
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- Effect of Structure of Photoresponsive Molecules on Photochemical Phase Transition of Liquid Crystals I. Synthesis and Thermotropic Properties of Photochromic Azobenzene Derivatives
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Seventeen azobenzene derivatives were synthesized and their thermotropic properties were examined.They are classified into three groups.In the first group, 4-cyanobiphenyl moieties are attached to both sides of azobenzene through various alkyl spacers: AB(nCB)2 where n = 3, 4, 5 and 6.In the second group, the 4-cyanobiphenyl moiety is attached to one side of the azobenzene, while the substituent of the other side was kept as OCH3:1ABnCB, where n = 3, 4, 5, 6 and 8.The third group is the azobenzene derivatives which possess alkoxy substituents at both para positions of azobenzene (nABm) or at various positions of the azobenzene phenyl rings (k,1ABn,m).The introduction of the 4-cyanobiphenyl group at the end(s) of the molecules is based on the attempt of highly efficient photochromic molecules to induce photochemical phase transition of liquid crystals by providing the photochromic trigger molecules with high affinity to the host liquid crystal.Both 1ABnCB and AB(nCB)2 exhibited the liquid crystalline phases, whereas among nABm and k,1ABn,m, only 1AB8 and 8AB8 showed the liquid crystalline phase.The 1ABnCB series exhibited a distinct odd-even variation in phase transition temperatures as well as enthalpy and entropy changes with the length of the flexible spacers, while the AB(nCB)2 series did not show clear odd-even variation except for the liquid crystal to isotropic phase transition temperatures.
- Ikeda, T.,Miyamoto, T.,Kurihara, S.,Tsukada, M.,Tazuke, S.
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p. 357 - 371
(2007/10/02)
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