Design of functional materials using liquid crystals as molecular templates


Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Chemical Engineering, Turkey

Approval Date: 2018

Thesis Language: English

Student: ASLI KARAUSTA

Principal Supervisor (For Co-Supervisor Theses): Emre Büküşoğlu

Co-Supervisor: Halil Kalıpçılar

Abstract:

Liquid crystal (LC) is a phase of material which is intermediate to a crystalline solid and an isotropic liquid such that the molecules flow but retain a degree of long-range orientational ordering. LCs, due to their long range orientational ordering and fluidic properties, can be used in templated synthesis of polymeric materials as well as self assembly of the microparticles incorporated into the LCs. In the first part of this thesis, we sought to provide control over alignment of the polymer chains, alignment and size of the pores within polymeric films with thickness of 20-200 m. For the synthesized polymeric materials, we used characterization methods such as thermal, optical, mechanical, nitrogen adsorption porosimetry and electron microscopy. As a result of these analysis, we found that it is possible to control both size distribution (between 5-50 nm-in-diameter) and alignment of pores, and the material exhibit alignment-dependent mechanical properties which are sufficient to be used in different applications such as separation, soft robotics, sensors and biomedical devices. In the second part of the thesis, we investigated the self-assembly of the inorganic particles of different shapes incorporated into LCs. The zeolite 4A particles used were cubic particles with truncated, sharp or round edges in a size range of 2-6 μm. The ZIF-L particles used were leave shaped particles with 400 nm thickness and 1-4 and 5-10 μm in length and width, respectively. The particles were observed to orient in a preferred direction and mediate anchoring conditions that lead to three-dimensional defect structures.