887764-00-3Relevant academic research and scientific papers
Self-assembly of an azobenzene-containing polymer prepared by a multi-component reaction: Supramolecular nanospheres with photo-induced deformation properties
Wang, Shuai,Zhang, Ning,Ge, Xiaopeng,Wan, Yingbo,Li, Xiaohong,Yan, Li,Xia, Yijun,Song, Bo
, p. 4833 - 4839 (2014)
In this article, we have synthesized a polymer containing regulated azobenzene groups by one-pot multi-component polymerization (MCP) based on Passerini reaction, and investigated its self-assembly behavior and photo-induced deformation properties. We found that this molecule can form spherical structures with sizes ranging from hundreds of nanometers to several micrometers when dissolved in THF. NMR and FTIR studies indicate that there are associated hydrogen bonds among the molecules in the aggregates, which are responsible for the formation of the nanospheres. By controlling the stirring rate as the THF suspension is dropped into water, the nanospheres can be sorted according to their size. In this way, we have obtained nanospheres with relatively uniform diameter. When irradiated by UV light in the aqueous medium, the nanospheres tend to aggregate into large clusters, while in dry state they are ready to merge into island-like structures, showing a good photo-induced deformation property.
Thermal and photoinduced liquid crystalline phase transitions with a rod-disc alternative change in the molecular shape
Tanaka, Daisuke,Ishiguro, Hisato,Shimizu, Yo,Uchida, Kingo
, p. 25065 - 25071 (2012)
A triphenylene derivative which has six 4-tetradecyloxyazobenzene units connected with propylene-ester linkages (1) was synthesised to study the liquid crystalline phase transitions in both thermotropic and photo-induced manners. It was found that 1 exhibits smectic A (SmA) and rectangular columnar (Col r) mesophases in an enantiotropic way. This means that 1 can behave as both rod- and disc-like molecules depending on the thermal condition. To the best of our knowledge, this is the first case in thermotropic liquid crystals where one compound exhibits both calamitic and discotic mesomorphism with the change of molecular shape in anisotropy. Under the photo-irradiation at 365 nm of wavelength which induces a photoisomerisation of azobenzene units from trans to cis forms, the phase transitions take place in the same manner as in the thermotropic ones with a certain decrease of phase transition temperatures. It is also a new finding that at 202.5°C at which 1 exhibits a Colr mesophase without photo-irradiation, the successive phase changes are induced by increasing the light intensity to the isotropic liquid (Iso) phase by way of a SmA phase. This means that the isothermal phase transitions among Iso, SmA and Colr phases can be controlled by light intensity. This is also the first example that the isothermal liquid crystalline phase transitions are controlled by photo-irradiation among three phases (Colr, SmA and Iso), which are also accompanied with the shape change of molecules between rod and disc.
