Chitosan molecules deposited from supercritical carbon dioxide on a substrate: Visualization and conformational analysis

We deposited single individual macromolecules of chitosan directly from their solutions in supercritical carbon dioxide onto a substrate surface and applied SFM method to analyze the macromolecular conformation. By means of image processing of many different SFM-contours of the visualized individual macromolecules, we determined the scaling exponent ν, which describes the correlation between mean square end-to-end distances and contour lengths of the adsorbed macromolecules. It was revealed, that the macromolecules, deposited from scCO 2 and visualized by SFM, tended to adopt rather extended conformation. The scaling exponent v was found to be in range of 0.78-0.8, which was slightly above the 3/4 value, corresponding to 2D self-avoiding walk statistics. Good adhesion of chitosan coatings directly deposited from scCO 2 is expected.