CARS imaging of nematic liquid crystal confined to mesoporous silica-based particles

Abstract

First application of CARS spectroscopy for visualization of probe liquid crystal (LC) molecules nanoconfined to mesoporous silica host is reported. Mesoporous molecular sieves (Al-MCM-41, KIT-6, and SBA-15) loaded with nematic 5CB as probe molecules were studied using a home-built CARS microscope. The images were registered in a forward mode in 1260–1700 cm⁻¹ spectral range. It was found that Al-MCM-41 showed the maximum density of the adsorbed species and the best filling uniformity among the studied hosts. The observed differences are explained by different active sites distribution and LC interaction with the host pore surface.

KEYWORDS:

• CARS
• 5CB
• confined liquid crystals
• Raman
• silica-based molecular sieves

Additional information

Funding

This work was supported in part by the National Academy of Sciences of Ukraine under the Ukrainian Governmental Program KPKVK 6541230 “In Support of Priority Research Development”, and under the Polish-Ukrainian Scientific Cooperation Program (Project “Structural and optical properties of disordered molecular systems for optoelectronics”), and by the Ministry of Education and Science of Ukraine in the frame of Ukrainian-Lithuanian Scientific Cooperation Program (project No. S-LU-18-6).