Surface morphology and ordering in side-chain liquid crystal diblock and homopolymer ultrathin films

Microphase-separated morphologies of side-chain liquid crystal (LC) diblock copolymers have been examined as substrate-supported thin films. The film thicknesses ranged from 0.5 to 10 times the block copolymer period (L). These novel materials are of interest because they exhibit self-oriented electro-optical properties in the bulk state, and may exhibit interesting field dependent nanometer-scale ordering as thin films. A primary challenge in taking advantage of these properties involves the fundamental understanding and control of the nano-domain morphology, which is strongly affected by the substrate, block copolymer properties, and LC alignment within the domains. In these studies, an amorphous side-chain LC diblock polymer system has been synthesized containing a side-chain mesogen with a chiral alkyl end. Experiments were conducted using Atomic Force Microscopy, Transmission Electron Microscopy, and X-ray Specular Reflectometry, to determine the complex surface morphology. Contact angle measurements and angle-resolved X-ray Photoelectron Spectrometry were also conducted to determine LC orientation at different interfaces. From this information, final models of complex morphologies were derived for different block copolymer compositions, including lamellar, cylindrical, and new smectic-bilayered morphologies. To better understand the ordering of the LC mesogen at different interfaces, LC homopolymer films were studied. LC anchoring was planar at the substrate, but homeotropic at the air interface due to exposure of the non-polar mesogen tail. Block copolymer thin films were then examined for compositions ranging from 40% to 85% weight fraction of the LC block.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Wu, Jung-Sheng, 1970-

Advisor dc:contributor.advisor

• Paula T. Hammond.

• 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/1721.1/8502

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8502