What is it about?
The lubrication of surfaces and the control of hydrophobicity (whether a surface likes or dislikes water) are tasks that can be achieved by coating surfaces with thin layers of polymers. In both cases, the hydration of the polymer film (the water contained within it, and associated directly with the polymer molecules) is a factor known to influence how effective the coatings are at controlling the surface properties. This paper looks at a common form of surface coating (polyelectrolyte multilayer) and the water within that coating, and interrogates both using a form of molecular spectroscopy (FTIR - Fourier transform infrared). By comparing data from FTIR spectroscopy with other techniques, we were able to determine the amount of water within the coating, the environment of the water within the coating (how the coating interrupted the interactions between water molecules), and how this information was correlated with the hydrophobicity of the surface upon which the coating was placed.
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Why is it important?
The key to the design of thin film coatings for lubrication and hydrophobicity control (as well as other applications such as anti-fouling coatings and surface-mediated drug delivery) is determining the connection between molecular parameters and the macroscopic properties of the surface. Only by making those connections does one have the required information to alter the chemistry of the coating in a rational manner, to obtain the desired coating properties. The work described in this publication is focused on that aim: connecting the composition and molecular environment of a coating with its wettability.
Perspectives
This paper is a follow-up investigation to two previous studies from the SISM Group (http://www.sism-at-unisa.net/). The first was our initial study into hydration water in polyelectrolyte multilayers (http://dx.doi.org/10.1021/la2045543), which was primarily a proof-of-principle demonstration that hydration water could be probed within confined polymer films. The second was our more recent study into the use of fucoidans (sulfated polysaccharides from seaweed) to make polyelectrolyte multilayers (http://dx.doi.org/10.1039/c4sm02552k). The most important aspect of the current work from my perspective is that it provides a platform for future studies of polymer film hydration, with more diverse polymer chemistries, and a focus on lubrication in addition to hydrophobicity.
Professor David Allan Beattie
University of South Australia
Read the Original
This page is a summary of: In Situ ATR FTIR Spectroscopic Study of the Formation and Hydration of a Fucoidan/Chitosan Polyelectrolyte Multilayer, Langmuir, October 2015, American Chemical Society (ACS),
DOI: 10.1021/acs.langmuir.5b01812.
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