One-step surface modification of poly(dimethylsiloxane) by undecylenic acid

Jinwen Zhou, Steven J.P. McInnes, Abdul Mutalib Md Jani, Amanda V. Ellis, Nicolas H. Voelcker

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Abstract

Poly(dimethylsiloxane) (PDMS) is a popular material for microfluidic devices due to its relatively low cost, ease of fabrication, oxygen permeability and optical transmission characteristics. However, its highly hydrophobic surface is still the main factor limiting its wide application, in particular as a material for biointerfaces. A simple and rapid method to form a relatively stable hydrophilised PDMS surface is reported in this paper. The PDMS surface was treated with pure undecylenic acid (UDA) for 10 min, 1 h and 1 day at 80 °C in a sealed container. The effects of the surface modification were investigated using water contact angle (WCA) measurements, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), and streaming zeta-potential analysis. The water contact angle of 1 day UDA-modified PDMS was found to decrease from that of native PDMS (110 °) to 75 °, demonstrating an increase in wettability of the surface. A distinctive peak at 1715 cm-1 in the FTIR-ATR spectra after UDA treatment was representative of carboxylation of the PDMS surface. The measured zeta-potential (ζ) at pH 4 changed from -27 mV for pure PDMS to -19 mV after UDA treatment. In order to confirm carboxylation of the surface visually, Lucifer Yellow CH fluorescence dye was reacted via a condensation reaction to the 1 day UDA modified PDMS surface. Fluorescent microscopy showed Lucifer Yellow CH fluorescence on the carboxylated surface, but not on the pure PDMS surface. Stability experiments were also performed showing that 1 day modified UDA samples were stable in both MilliQ water at 50 °C for 17 h, and in a desiccator at room temperature for 19.5 h.

Original languageEnglish
Title of host publicationProceedings
Volume7267
DOIs
Publication statusPublished - 1 Dec 2008
Externally publishedYes
EventSmart Materials V - Melbourne, VIC, Australia
Duration: 10 Dec 200812 Dec 2008

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
PublisherSPIE
ISSN (Print)0277-786X

Conference

ConferenceSmart Materials V
CountryAustralia
CityMelbourne, VIC
Period10/12/0812/12/08

Keywords

  • Biointerfaces
  • Fluorescence dye
  • Microfluidic devices
  • Poly(dimethylsiloxane) (PDMS)
  • Surface wettability
  • Zeta-potential analysis

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