Involvement of cyan and ester groups in surface interactions of aerosil–cyanophenyl alkyl benzoate systems with high silica density: Infrared investigations
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- 作者：Ligia Frunza ; Stefan Frunza ; Irina Zgura ; Traian Beica ; Nicoleta Gheorghe ; Paul Ganea ; Daniel Stoenescu ; Adrian Dinescu ; Andreas Schö ; nhals
- 关键词：Cyanophenyl alkyl benzoate ; Aerosil composites ; Infrared spectra ; Band shape analysis
- 刊名：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
- 出版年：2010
- 出版时间：April 2010
- 年：2010
- 卷：75
- 期：4
- 页码：1228-1235
- 全文大小：763 K
文摘
Composites prepared from aerosil A380 and liquid crystals (LCs) of 4-n-alkyl-4′-cyanophenyl benzoate type, with four to six carbon atoms in the alkyl chain were investigated by infrared spectroscopy. Their high silica content (of 2–7 g aerosil/1 g of LC) was given by thermogravimetric investigations and allows the observation of a rather thin LC layer on the silica particles. Several surface species onto the external surface of the grains were demonstrated. Arguments are given that monomer and dimer species are present in the bulk cyanophenyl benzoate materials while bulk-like species along with hydrogen-bonded ones coexist in the so-called surface layer of the composites. The main interaction of LC molecules with the aerosil surface is by hydrogen bonding taking place with the involvement of the cyan group. There is a contribution of ester carbonyl group to these surface interactions but this cannot be well quantified.