Doctoral Dissertations

Date of Award

8-2002

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Chemistry

Major Professor

Mark D. Dadmun

Committee Members

Jeffery Kovac, Roberto Benson, Robert Hinde

Abstract

Blending a liquid crystalline polymer (LCP) with an amorphous polymer to create a molecular composite offers a method to use the desirable properties of a LCP at a more modest cost. However, very few such blends are miscible. This study seeks to correlate the extent of intermolecular hydrogen bonding between the two polymers in a blend with the phase behavior of the blend. Using Fourier Transform Infrared technique to quantify the amount of intermolecular hydrogen bonding between the two polymers and Differential Scanning Calorimetry and optical microscopy to determine the blend phase behavior, this study provides results which demonstrate that the broadest miscibility window in the blends studied corresponds to the system that optimizes the extent of intermolecular hydrogen bonding. The first part of this study demonstrates that it is possible to create a true molecular composite by inducing miscibility in a blend containing a LCP and an amorphous polymer by slightly modifying the structure of the amorphous polymer to promote hydrogen bonding between the two polymers. The system that maximizes the extent of intermolecular hydrogen bonding is one where the hydrogen bonding moieties on one of the polymers are spaced out along the chain. The results show that by optimizing the extent of hydrogen bonding between the two blend components, the broadest miscibility window in the phase diagram can be found. To sum up, these results provide guidelines by which miscibility may be induced in polymer blends by such minor structural modification of the polymers.

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