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X-PEEM Study on Surface Orientation of Stylized and Rubbed Polyimides
Cossy-Favre1, Díaz, Liu
1Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, BHP Steel Institute, University of Wollongong, Wollongong NSW 2522, Australia, and Almaden Research Center, IBM Research Division, San Jose, California 95120.
Macromolecules
|July 29, 1998
Summary
X-ray photoelectron emission microscopy revealed that polyimide films require significantly less stress for surface orientation than previously thought. Stylizing polyimide films showed lower orientation stress (45 MPa) compared to bulk yield stress.
Area of Science:
- Materials Science
- Surface Science
- Polymer Science
Background:
- Polyimide thin films are crucial in various electronic and optical applications.
- Understanding and controlling surface molecular orientation is key to optimizing film performance.
- Conventional rubbing methods can induce inhomogeneities in polymer orientation.
Purpose of the Study:
- To investigate the surface orientation of polyimide thin films using X-ray photoelectron emission microscopy (X-PEEM).
- To model the rubbing process using a stylizing technique and determine the critical stress for molecular orientation.
- To compare the orientation behavior of stylized films with conventionally rubbed films.
Main Methods:
- Utilized X-ray photoelectron emission microscopy (X-PEEM) for high-resolution surface imaging.
- Employed near-edge X-ray absorption fine structure (NEXAFS) spectroscopy for molecular orientation analysis.
- Developed a stylizing method to precisely control and measure local stress on polyimide films.
Main Results:
- Determined the minimum normal stress required to orient BPDA-PDA polyimide films to be 45 MPa.
- This orientation stress is substantially lower than the bulk yield stress (200-300 MPa).
- Observed lateral inhomogeneities in polymer surface orientation for conventionally rubbed polyimide films.
Conclusions:
- X-PEEM is an effective technique for studying surface orientation in polymer thin films.
- The stylizing method provides a controlled approach to understanding molecular orientation mechanisms.
- Polyimide surface orientation can be achieved with significantly lower stress than bulk deformation, highlighting surface-specific phenomena.