Plasma Processing of Low Vapor Pressure Liquids to Generate Functional Surfaces.

Sandra Gaiser,Urs Schütz,Dirk Hegemann,Patrick Rupper

doi:10.3390/molecules25246024

Abstract

The concept of depositing solid films on low-vapor pressure liquids is introduced and developed into a top-down approach to functionalize surfaces by attaching liquid polyethylene glycol (PEG). Solid-liquid gradients were formed by low-pressure plasma treatment yielding cross-linking and/or deposition of a plasma polymer film subsequently bound to a flexible polydimethylsiloxane (PDMS) backing. The analysis via optical transmission spectroscopy (OTS), optical, confocal laser scanning (CLSM) and scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) as well as by water contact angle (WCA) measurements revealed correlations between optical appearance, chemical composition and surface properties of the resulting water absorbing, covalently bound PEG-functionalized surfaces. Requirements for plasma polymer film deposition on low-vapor pressure liquids and effective surface functionalization are defined. Namely, the thickness of the liquid PEG substrate was a crucial parameter for successful film growth and covalent attachment of PEG. The presented method is a practicable approach for the production of functional surfaces featuring long-lasting strong hydrophilic properties, making them predestined for non-fouling or low-friction applications.

Highlights

The deposition of thin films on solid substrates via low-pressure processes is a well-known approach for a wide range of applications
We subsequently present our novel approach for the plasma processing of liquids allowing the formation but simultaneous functionalization of thin films on liquid substrates
Other groups followed this approach using different kinds of liquid substrate materials, such as silicone oils, ionic liquids and vegetable oils, to synthesize metal films and nanoparticles made of gold, silver, titanium, aluminum, iron, nickel and copper via sputtering and thermal evaporation processes [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27]

Summary

Introduction

The deposition of thin films on solid substrates via low-pressure processes is a well-known approach for a wide range of applications. The first attempt to coat liquids was made by Ye et al, who successfully deposited continuous metallic films on silicone oil by RF magnetron sputtering and investigated the nucleation and growth mechanisms taking place during film formation [1,2,3] Other groups followed this approach using different kinds of liquid substrate materials, such as silicone oils, ionic liquids and vegetable oils, to synthesize metal films and nanoparticles made of gold, silver, titanium, aluminum, iron, nickel and copper via sputtering and thermal evaporation processes [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27].

Methods

Results

Discussion

Conclusion