Influence of the size and the attached organic tail of modified detonation nanodiamond on the physical properties of liquid crystals

Abstract

For the functionalisation of the detonation nanodiamond (DND), we attached via grafting carboxylate groups, leading to only one of such groups per 5000–6000 carbon units. Activation of the COOH-surface functionalised groups allowed the attachment of various organic tails. Dielectric and electro-optical properties of nematic liquid crystalline mixtures (LCMs) doped with modified DND (MDND) have been investigated. It is established that the effect of MDND on the dielectric properties of the LCMs depends on the size of the nanoparticles and the type of rod-like elongated organic molecules attached to the MDND. It was found that nanoparticles of small size (4–5 nm) do not significantly affect the parameters of LCMs. At the same time, the conglomerates based on MDND of about 50 nm or about 100 nm in diameter can increase or decrease the dielectric anisotropy and the response time of LCMs to about 1.5–2.5 times, depending on the polarity of the tails.

Keywords:

• modified detonation nanodiamond
• nematic liquid crystal
• electro-optical response
• dielectric anisotropy

Funding

W.H. acknowledges the financial support from German Science Foundation [Ha 782/98-1].