# Presentation: 422007

## Interfacial  Characteristics of Semi fluorinated Polymers Dvora Perahia (Clemson University)  DMR 0203660

- Thin layers of semifluorinated and fluorinated polymers has a potential to improve variety of applications including  low non-adhesive coatings, electrochemical membranes, low dielectric layers for molecular electronics, wave guides and  many others.
- Introducing a fluorine atom into a polymeric chain increases the chemical and thermal stability, increases the internal segregation, and affects the dielectric and refractive indices of the polymers. Further more, the intermolecular segregation enhancement leads to ordering that may express itself in the formation of liquid crystalline phases or enhanced crystallinity. In thin films interfile energies coupled with the flexibility of the chains, become significant in defining the properties of the thin polymeric films.

- Figure 1 introduces the chemical formula of a member of the PFCB family. Figure 2 shows polarized optical microscopy images of 8CB, a model liquid crystalline molecule in its nematic (top) and smectic (bottom)  phases. Figure 3 introduces an X-ray pattern of the smectic phase, on top of the PFCB as a proof that the smectic phase was not destroyed.

- Polymer Preprints (American Chemical Society,
- Division of Polymer Chemistry) ***2005***,  46(2),  616-617,
- 46(2),  593-594. Macromolecules, submitted ***2005****.*

- PFCB based polymers (Fig 1) were used to probe the effects of added fluorine on the structure, dynamics and properties of thin semifluorinated layers, and their potential as orientaion layers (Fig 2 and 3).

- Figure 1

- Figure2

- Figure 3

- On glass

- On PFCB

- On Glass

- On PFCB

## Education

**Education**
- Four graduate students have been pursuing their Ph.D. Work on this topic. Dr. Rakchart Triphol (graduated 2003), is a professor in Naresuan University in Thailand. Mr. Gang Cheng (will graduate in December 2005),  and join HIFER in Oak Ridge, Mr. Bryan Spaul, (will graduate in December 2005) and take a position as a synthetic chemist in Industry, and Mr. Lilin, who is a 3rd year graduate student.
- All students have been trained to use neutron based techniques for material research. The participated in a Summer School for X-ray and Neutron Studies at Argonne National Laboratory, a joined NSF/DOE project. With the state of the art neutron source being developed

**Interfacial  Characteristics of Semi fluorinated Polymers ****Dvora Perahia (Clemson University)  ****DMR**

- at Oak Ridge TN, this training is critical to the education of a new generation of material researchers whom will be able take advantage of the unique technique the facility will offer.

**Technology Transfer Potential**

- The current work has demonstrated that PFCB based polymers exhibit potential as an alignment layer in liquid crystal based devices, where the degree of fluorination and the flexibility of the chains provide a control  to the direction of alignment and switching time. It will advance significantly the current industrial process that utilizes mechanical rubbing of polymeric layers, or photo treatments that result in non reproducible surfaces.

- Journal of the American Chemical Society  **2004**,  126(40),  12772-12773.