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Fabrication of Large-area Free-standing Ultrathin Polymer Films
Published on: June 3, 2015
Large scale crystallinity in kinetically stable polythiophene-based Langmuir-Blodgett films
Jusroop S Mattu1, Gary W Leach
1Department of Chemistry, 4D LABS, and Laboratory for Advanced Spectroscopy and Imaging Research, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6 Canada.
Journal of the American Chemical Society
|February 11, 2010
Summary
Researchers observed large-scale molecular ordering in poly(3-alkylthiophene) films. These stable, ordered films, fabricated using the Langmuir-Blodgett method, offer insights into polymer morphology and properties.
Area of Science:
- Materials Science
- Polymer Science
- Nanotechnology
Background:
- Poly(3-alkylthiophene)s are crucial in organic electronics.
- Achieving molecular-level ordering in thin films is challenging.
- Controlling film morphology impacts electronic properties.
Purpose of the Study:
- To report the first direct observation of large-scale molecular ordering in complex poly(3-alkylthiophene)-based thin films.
- To fabricate and characterize highly ordered thin films using a specific amphiphilic polythiophene derivative.
- To investigate the relationship between film morphology and physical properties.
Main Methods:
- Langmuir-Blodgett (LB) deposition for layer-by-layer film fabrication.
- X-ray diffraction (XRD) to confirm long-range order and bilayer separation.
- Molecular resolution atomic force microscopy (AFM) for in-plane crystalline domain analysis.
- Polarized optical microscopy (POM) for macroscopic domain observation.
- FeCl(3) doping to study electrical conductivity anisotropy.
Main Results:
- Successful fabrication of kinetically stable, high optical quality thin films from poly(3-(11-(2-tetrahydropyranyloxy)undecyl)thiophene) (PTHPUDT).
- XRD confirmed long-range order normal to the surface (~30 A bilayer separation).
- AFM revealed highly ordered crystalline domains with parallel, closed-packed polythiophene chains.
- POM showed large-scale domains with uniform optical retardation.
- FeCl(3)-doped films exhibited anisotropic conduction, with higher transport perpendicular to the main chain.
Conclusions:
- PTHPUDT films exhibit unprecedented large-scale molecular ordering and kinetic stability.
- The amphiphilic nature and polymer backbone structure contribute to this stability and order.
- These ordered films serve as an ideal model system for understanding morphology-property relationships in conjugated polymers.
- Anisotropic conduction suggests potential for directed charge transport applications.
