Electronic Nanodevices from LiquidCrystals

Abstract

Phytantriol is a well-known amphiphilic lipid which self-assembles into a range of mesophases, including the bicontinuous cubic phase, and have been used in cosmetic products and drug delivery [1, 2]. The phases which are stable in excess water can be exploited as a template for generating hard nano-materials. In this research, phytantriol mesophases were formed using a solvent penetration experiment, which is a dry lipid in contact with water. The formation of mesophases was confirmed by cross-polarised light microscopy (CPLM)and small-angle X-ray scattering (SAXS) techniques. SAXS measurements al-lowed the optically inactive phases gyroid and diamond inverse bicontinuous cubic phases QGII and QDII to be distinguished. The dynamic hydration of phytantriol mesophases as a function of time was addressed by CPLM and SAXS techniques. CPLM was exploited to track the position of boundaries between optically active and inactive phases as a function of time and temperature. Specifically, boundaries representing lyotropic transitions to and from the lamellar phase Lα(transitions: LII to Lα, and Lα to QGII) were analysed and their displacements evolvedast0.5, reflecting diffusive transport of water. This enables us to quantify the propagation of each boundary by a diffusivity constant D using a simple diffusive model [3]. The experiments were performed between 18 to 55◦C. Surprisingly, the diffusivity drops at temperatures 35◦C and above, and these findings are dis-cussed. Using SAXS, the dynamic hydration was studied as a function of time at room temperature and the lattice parameters of the QGII and QDII mesophases were obtained as a function of time. A simple method to produce oriented phases of phytantriol is demonstrated. This was achieved by two procedures: (a) a phytantriol droplet was placed be-tween glass slides and hydrated at temperatures 25, 30 and 35◦C, (b) phytantriol, that was filled in a tube, was hydrated for a long duration at room temperature. In the procedure (a), the CPLM technique was used to confirm the alignment 2of the optically active phase, Lα, which appeared as a dark CPLM image from a top microscope, while a bright image appeared when looking at the sample from an angle 45◦from the top microscope. The dark CPLM images indicate the alignment of the lamellar sheet with glass slides. In the procedure (b), oriented mesophases of the optically active and inactive mesophases (Lα, QGII and QDII) were confirmed by SAXS, where diffraction spots were observed instead of diffraction rings, indicating oriented mesophases. The oriented phases depended on the time of hydration and the timescale of hydration of each phase to obtain an oriented phase varied: three days for the Lαphase, a month for the QGII phase and three months for the QDII phase. A novel approach for fabricating of electronic nanodevices was investigated. The QDII phase from phytantriol was used as a template to fabricate nanomaterials via the electrodeposition process. In the electrodeposition process, a working electrode is used to deposit a target material on its surface. Here, instead of one working electrode, two working electrodes separated by a sub-millimeter sized gap were used, and the material was deposited across the gap. This approach produces nanomaterials with its electrodes allowing characterisation of the nano-materials electrically, which provides technological advantages for future devices. We started testing the approach with platinum (Pt), as it has been successfully deposited through the phytantriol template [4]. The production of material across the gap was achieved with one sample among 15 samples. The formation of the Pt-nanostructure across the gap was confirmed by measuring the resistance by a multimeter, which found to be 180 Ω. In con