Polymer mixture thermodynamics and applications for functional, microstructured films
Date
2017
Authors
Journal Title
Journal ISSN
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Publisher
University of Delaware
Abstract
Polymer blend films are used in applications including organic optoelectronics
and pressure sensitive adhesives. The film microstructure (domain size and
composition) is a critical component that determines the material properties (e.g.
friction coefficient). The morphology in these films is dictated by the
thermodynamics and kinetics of phase separation in addition to the processing
conditions, such as solvent evaporation, during film generation. ☐ In this dissertation, the relationships between phase separation and casting
conditions on microstructure and the effect of the resulting morphology on the friction
coefficient were studied to produce targeted structures in multicomponent, hierarchical
polymer blend films. First, a robust method was developed and implemented to
measure polymer-solvent interaction parameters, which were used to predict the phase
diagram in polymer blend solutions. The influence of the phase separation on the
casting behavior was captured using in situ techniques. Second, the casting behavior
and morphology of polymer blends was tuned through the addition of nanoparticles.
The solvent quality, a parameter that has not previously been explored in polymer
blend nanocomposites, was shown to impact the effect of the nanoparticles on the
microstructure. Third, the relationships between the structure, composition, and
friction coefficient were established to provide insight into rational design of
tribologically-relevant materials like pressure sensitive adhesives. Finally, the
techniques and methodologies developed in this dissertation were applied to
renewable polymers to study the solvent-polymer interactions, surface energies, and
friction coefficients towards incorporating these sustainable materials into green,
structured coatings. ☐ Overall, this dissertation provides enhanced understanding and robust methods
to characterize and control interactions in polymer blend films. These insights afford
control over the final material properties through modifying the film morphology. The
methods outlined in this work can be applied to polymer blend systems of interest for
rational design of functional, hierarchical materials.