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Chemical modification and photograft polymerization upon expanded poly(tetrafluoroethylene)
I Noh1, S L Goodman, J A Hubbell
1Department of Chemical Engineering, University of Texas, Austin 78712, USA.
Journal of Biomaterials Science. Polymer Edition
|July 2, 1998
Summary
Surface modification of Poly(tetrafluoroethylene) (PTFE) films enhances hydrophilicity and biocompatibility. Graft polymerization with PEG-Ac creates a more hydrophilic surface, suitable for modulating biological interactions on ePTFE materials.
Area of Science:
- Materials Science
- Surface Chemistry
- Polymer Science
Background:
- Poly(tetrafluoroethylene) (PTFE) exhibits excellent chemical resistance but poor surface wettability.
- Surface modification is crucial for tailoring PTFE properties for specific applications, particularly in biomedical fields.
Purpose of the Study:
- To develop a surface modification method for PTFE and expanded PTFE (ePTFE) to enhance hydrophilicity and suitability for biological applications.
- To investigate the effectiveness of benzophenone/sodium hydride reduction followed by photograft polymerization.
Main Methods:
- Surface reduction of PTFE films using benzophenone and sodium hydride in dimethylformamide at elevated temperatures.
- Photograft polymerization of sodium styrenesulfonate (SS-Na) and poly(ethylene glycol) monoacrylate (PEG-Ac) onto modified PTFE surfaces using UV irradiation.
- Surface characterization using Electron Spectroscopy for Chemical Analysis (ESCA) and dynamic water contact angle measurements.
- Modification and analysis of expanded PTFE (ePTFE) surfaces, including lumenal, exterior, and pore surfaces.
Main Results:
- Surface reduction of PTFE led to defluorination, oxygen incorporation, and increased unsaturation, significantly reducing water contact angles.
- Photograft polymerization of PEG-Ac further increased surface hydrophilicity (contact angle reduced to 36 degrees) and introduced ester functionalities.
- Successful modification of ePTFE surfaces, including internal pore structures, was confirmed by ESCA analysis, with minimal morphological damage observed via SEM.
Conclusions:
- The combined reduction and photograft polymerization technique effectively modifies PTFE and ePTFE surfaces, enhancing hydrophilicity.
- This method offers a pathway to modulate biological interactions on ePTFE by altering surface chemistry with minimal impact on material morphology.
- The modified ePTFE surfaces show potential for advanced biomedical applications requiring tailored surface properties.