A simple process to tune wettability of pectin-modified silanized glass

Abstract

Layer-by-layer (LbL) techniques are strategically important to obtain highly organized and oriented materials. Understanding film formation and nanoscale structures at the interface is important for many biological, industrial and technological processes. We describe a LbL film formed from a silanized glass surface coated with high-methoxyl pectin. The chemical composition of the surfaces was characterized by X-ray photoelectron spectroscopy (XPS); surface topology and chemistry were analyzed by Atomic Force Microscopy coupled with Infrared Spectroscopy (AFM-IR). Varying pH and concentration of the casting pectin solutions results in surfaces with different wettability, measured by contact angle. At high pH, pectin chains are highly charged, resulting in chain repulsions, poor coverage and low wettability due to exposure of the silane chains. At higher concentration, chains extend from the surface and wettability increases. This work establishes a facile route towards value-added materials from pectin, establishing clear links between wettability, nanostructure and composition at the interface.