Colloids and Surfaces A: Physicochemical and Engineering Aspects
2019
A SIMPLE PROCESS TO TUNE WETTABILITY OF PECTIN-MODIFIED SILANIZED GLASS
JONATAS U. NASCIMENTO; GIOVANA C. ZAMBUZI; JOAO FERREIRA; JULIA H. PAULA; TATIANA S. RIBEIRO; ADRIANO L. SOUZA; CÉCILE A. DREISS; LUCIMARA L. SILVA; KELLY R. FRANCISCO 

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.

Layer-by-layer deposition of silane and pectin on glass surfaces

Glass slides (3 cm × 1 cm) with or without gold were used as substrates. Prior to silane and pectin deposition, glass slides were immersed in various solvents in order to clean their surface in an ultrasonic bath for 20 min, in the following order: water, acetone and ethanol. Thin films of macromolecules on the glass surfaces were prepared by using a dip-coater (ND-R Rotatory Dip Coater, Nadetech Innovations).

 

Keywords: Pectin; Silanized glass; pH; Layer-by-layer; Wettability