Description of Research:

Topics of Interest:

1. Thin Film Nanocomposites

2. Thin Polymer Films

3. Organic Electronics

4. Polymer Dynamics

5. Electrorheological Fluids

Thin Films

Wetting Image

Role of intermolecular forces

Polymer thin films, with thicknesses in the range of 5-100 nanometers, often exhibit properties that manifest the influence of confinement and of interfacial interactions between the material constituents and the external interfaces. 

 

Intermolecular forces may influence the morphological structure of sufficiently thin films:  films may be induced to “break-up,” or the molecules may self-organize into patterns, depending on the chemical structure and the local environment. We have also demonstrated that the morphological structure can be precisely controlled by the molecular architecture.

 

Shown to the left are the remnants of a polymer film after it has been annealed for a week at temperatures well above the Tg of the polymer film. We have demonstrated that the interfacial interactions can be tailored through the control of the molecular architecture.

 

confinement figure

Size dependent Phenomenon

Generally, size dependent phenomena in the macromolecular systems occur at very large length-scales compared to the behavior atomic systems (metals, semiconductors etc.) The length-scales of the thickness dependencies may vary from nanometers to 100s nm, depending on the property. The glass tranisition temperature exhibits a significant thickness dependence on the order of 10s of nanometers, while the physical aging rate does on the order of 100s of nanometers. It has also been demonstrated that the thickness dependence of such properties can be controlled through control of the molecular architecture.

 

Shown to the left is the thickness dependence of the glass transition temperature (top) and the phsyical aging rate (bottom) as a function of the molecular architecture.