- Thermostable birefringent copolyimide films based on azobenzene-containing pyrimidine diamines
-
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
-
-
Read Online
- Method for preparing polyimide polymer with azo-pyrimidine structure unit
-
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.
- -
-
Paragraph 0104
(2016/10/09)
-
- Photoliquefiable ionic crystals: A phase crossover approach for photon energy storage materials with functional multiplicity
-
Ionic crystals (ICs) of the azobenzene derivatives show photoinduced IC-ionic liquid (IL) phase transition (photoliquefaction) upon UV-irradiation, and the resulting cis-azobenzene ILs are reversibly photocrystallized by illumination with visible light. The photoliquefaction of ICs is accompanied by a significant increase in ionic conductivity at ambient temperature. The photoliquefaction also brings the azobenzene ICs further significance as photon energy storage materials. The cis-IL shows thermally induced crystallization to the trans-IC phase. This transition is accompanied by exothermic peaks with a total ΔH of 97.1 kJmol-1, which is almost double the conformational energy stored in cisazobenzene chromophores. Thus, the integration of photoresponsive ILs and self-assembly pushes the limit of solar thermal batteries.
- Ishiba, Keita,Morikawa, Masa-Aki,Chikara, Chie,Yamada, Teppei,Iwase, Katsunori,Kawakita, Mika,Kimizuka, Nobuo
-
supporting information
p. 1532 - 1536
(2015/02/05)
-
- Effect of Structure of Photoresponsive Molecules on Photochemical Phase Transition of Liquid Crystals I. Synthesis and Thermotropic Properties of Photochromic Azobenzene Derivatives
-
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.
-
p. 357 - 371
(2007/10/02)
-