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Licensed Unlicensed Requires Authentication Published by De Gruyter April 1, 2017

Biomimetic nanostructures for the silicone-biosystem interface: tuning oxygen-plasma treatments of polydimethylsiloxane

Bekim Osmani, Gabriela Gerganova and Bert Müller

Abstract

Polydimethylsiloxanes (PDMS) have drawn attention because of their applicability in medical implants, soft robotics and microfluidic devices. This article examines the formation of dedicated nanostructures on liquid submicrometer PDMS films when exposed to oxygen-plasma treatment. We show that by using a vinyl-terminated PDMS prepolymer with a molecular weight of 800 g/mol, one can bypass the need of solvent, copolymer, or catalyst to fabricate wrinkled films. The amplitude and periodicity of the wrinkles is tuned varying the thickness of the PDMS film between 150 and 600 nm. The duration of the plasma treatment and the oxygen pressure determine the surface morphology. The amplitude was found between 30 and 300 nm with periodicities ranging from 500 to 2800 nm. Atomic force microscopy was used to measure film thickness, amplitude and wrinkle periodicity. The hydrophobic recovery of the nanostructured PDMS surface, as assessed by dynamic contact angle measurements, scales with nanostructure’s fineness, associated with an improved biocompatibility. The mechanical properties were extracted out of 10,000 nanoindentations on 50×50-μm2 spots. The mechanical mapping with sub-micrometer resolution reveals elastic properties according to the film morphology. Finally, we tailored the mechanical properties of a 590±120-nm-thin silicone film to the elastic modulus of several MPa, as required for dielectric elastomer actuators, to be used as artificial muscles for incontinence treatments.

Acknowledgments

The financial support of the nano-tera.ch initiative (grant/award no. “SmartSphincter RTD2013”), project SmartSphincter, as well as the Swiss Nanoscience Institute (SNI) for the financial contribution to the AFM is gratefully acknowledged. The authors also thank Dr. Thomas Pfohl and Dr. Tino Töpper for the discussion of the results presented.

  1. Conflict of interest statement: Authors state no conflict of interest. All authors have read the journal’s publication ethics and publication malpractice statement available at the journal’s website and hereby confirm that they comply with all its parts applicable to the present scientific work.

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Received: 2017-2-2
Accepted: 2017-3-2
Published Online: 2017-4-1
Published in Print: 2017-4-1

©2017 Walter de Gruyter GmbH, Berlin/Boston