Morphological studies of polymeric systems with liquid crystalline order

This thesis addresses the structure, properties, and processing of various liquid crystal polymer systems. Morphologies of microphase separated side chain liquid crystal block copolymers are determined, both in the bulk and when confined to thin films. We show for the first time how these materials could potentially be used as a novel kind of surface stabilized liquid crystal display device. Magnetic field induced structures in a thermotropic main chain liquid crystal homopolymer were also examined. Defects in orienting fields are of interest because liquid crystal displays must be defect free over large areas. A study of the interaction of defects in an applied field yields information towards optimally processing these materials in order to minimize or completely eliminate these defects. The basic building block of the systems investigated is a liquid crystal mesogen. Liquid crystal mesogens are easily oriented by electric, magnetic, and flow fields and interact with polarized light such that they are desirable materials for display devices. Additionally, these systems are all polymeric, lending the complexity of the molecules' long-chain nature to the material properties, and the resulting processing challenges and mechanical advantages inherent to polymers. Polarized light microscopy (PLM), high resolution scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), small angle X-ray scattering (SAXS), and wide angle X-ray scattering (WAXS) are the tools employed. Two-dimensional Ndel inversion walls formed in a nematic monodomain during magnetic realignment of a highly elastically anisotropic thermotropic liquid crystal polyether are examined via PLM and AFM.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2003

Author dc:creator

• O'Rourke, Mary Jane Elizabeth.

Advisor dc:contributor.advisor

• Edwin L. Thomas.

• Chemical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/29292

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/29292