Photo-switching and nonlinear optical behaviors of center linked bent-core azobenzene liquid crystalline polymers

A new class of two series ( I and II ) of center linked bent-core azobenzene liquid crystalline polymers were prepared. They were prepared from two different spacer lengths (2 and 10) between polymer backbone and bent-core mesogen. The bent-core mesogen possesses photoactive linking group with varia...

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Bibliographic Details
Published in:Journal of materials science 2011-08, Vol.46 (15), p.5029-5043
Main Authors: Vijay Srinivasan, M., Kannan, P.
Format: Article
Language:English
Subjects:
Azo compounds
Azo polymers
Backbone
Calorimetry
Characterization and Evaluation of Materials
Chloroform
Classical Mechanics
Crystal structure
Crystallinity
Crystallography and Scattering Methods
Infrared spectroscopy
Isomerization
Liquid crystal polymers
Liquid crystals
Materials Science
Mesophase
Monomers
Neodymium lasers
NMR spectroscopy
Nonlinear optics
Nonlinearity
Nuclear magnetic resonance spectroscopy
Optical microscopy
Optical properties
Polymer liquid crystals
Polymer Sciences
Polymers
Prepolymers
Refractivity
Semiconductor lasers
Solid Mechanics
Spectrum analysis
Stability analysis
Switching
Thermal stability
Thermogravimetric analysis
Thin films
YAG lasers
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Summary:A new class of two series ( I and II ) of center linked bent-core azobenzene liquid crystalline polymers were prepared. They were prepared from two different spacer lengths (2 and 10) between polymer backbone and bent-core mesogen. The bent-core mesogen possesses photoactive linking group with variable terminal chains (7, 8, and 9). The synthesized precursors, monomers, and polymers were characterized by FT-IR, 1 H NMR, and 13 C NMR spectroscopy. Thermal stability of polymers was examined by thermogravimetric analysis. The mesophase transition of monomers and polymers were observed through polarized optical microscopy, and confirmed by differential scanning calorimetry. Among the two series of polymers, the second series of polymers possesses liquid crystalline properties. The photo-switching properties of bent-core azo polymers were investigated using UV–Vis spectroscopy, trans to cis isomerization occurs around 35 s in chloroform and 65 s in thin film, where as reverse processes take place almost 32 h in chloroform. The photo-switching processes of polymer IIa precedes faster and also longer time thermally stable when compared with recently reported similar polymers. Negative optical nonlinear refractive index and optical limiting properties of the polymers were measured using Nd-YAG laser.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-011-5423-x