Photoinduced Changes of Surface Topography in Amorphous, Liquid-Crystalline, and Crystalline Films of Bent-Core Azobenzene-Containing Substance
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- 作者：Alexey Bobrovsky ; Konstantin Mochalov ; Vladimir Oleinikov ; Daria Solovyeva ; Valery Shibaev ; Yulia Bogdanova ; Vĕra Hamplová ; Miroslav Kašpar ; Alexej Bubnov
- 刊名：Journal of Physical Chemistry B
- 出版年：2016
- 出版时间：June 9, 2016
- 年：2016
- 卷：120
- 期：22
- 页码：5073-5082
- 全文大小：654K
- 年卷期：0
- ISSN：1520-5207
文摘
Recently, photofluidization and mass-transfer effects have gained substantial interest because of their unique abilities of photocontrolled manipulation with material structure and physicochemical properties. In this work, the surface topographies of amorphous, nematic, and crystalline films of an azobenzene-containing bent-core (banana-shaped) compound were studied using a special experimental setup combining polarizing optical microscopy and atomic force microscopy. Spin-coating or rapid cooling of the samples enabled the formation of glassy amorphous or nematic films of the substance. The effects of UV and visible-light irradiation on the surface roughness of the films were investigated. It was found that UV irradiation leads to the fast isothermal transition of nematic and crystalline phases into the isotropic phase. This effect is associated with E–Z photoisomerization of the compound accompanied by a decrease of the anisometry of the bent-core molecules. Focused polarized visible-light irradiation (457.9 nm) results in mass-transfer phenomena and induces the formation of so-called “craters” in amorphous and crystalline films of the substance. The observed photofluidization and mass-transfer processes allow glass-forming bent-core azobenzene-containing substances to be considered for the creation of promising materials with photocontrollable surface topographies. Such compounds are of principal importance for the solution of a broad range of problems related to the investigation of surface phenomena in colloid and physical chemistry, such as surface modification for chemical and catalytic reactions, predetermined morphology of surfaces and interfaces in soft matter, and chemical and biochemical sensing.