title: Electrochemical Insights on the Hydrophobicity of Cellulose Substrates Imparted by Enzymatically Oxidized Gallates with Increasing Alkyl Chain Length.
abstract: In this work, we studied the influence of the alkyl chain length in enzymatically oxidized gallates on the development of hydrophobicity on paper-based materials, and further correlated the obtained effect to the redox mechanism of the enzymatic treatment. Laccase (Lac) enzyme was used to oxidize various members of the gallate homologous series in the presence or not of lignosulfonates (SL) to produce several functionalization solutions (FS), which were subsequently applied to cellulosic substrates. The hydrophobicity of the substrates was then assessed by means of water drop test (WDT) and contact angle (WCA) measurements. Hydrophobicity peaked reaching WDT and WCA values around 5000 s and 130°, respectively, and then decreased with increasing length of the hydrocarbon chain of gallate. Cyclic voltrammetry (CV) was used to study the effect of SL on the redox reactions of several gallates. The intensity of the anodic peak in their voltammograms decreased increasing the chain length of the gallate. The electrochemical behavior of lauryl gallate (LG) differed from that of other gallates. The fact that the voltammetric curves for SL and LG intersected at a potential of 478 mV indicates an enhancing effect of SL on LG oxidation at high potentials (above 478 mV).
authors.affiliation: †CELBIOTECH_Paper Engineering Research Group, Universitat Politècnica de Catalunya BarcelonaTech, Colom 11, E-08222 Terrassa, Spain.
authors.forename: Oriol
authors.initials: O
authors.lastname: Cusola
authors.affiliation: †CELBIOTECH_Paper Engineering Research Group, Universitat Politècnica de Catalunya BarcelonaTech, Colom 11, E-08222 Terrassa, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Valls
authors.affiliation: †CELBIOTECH_Paper Engineering Research Group, Universitat Politècnica de Catalunya BarcelonaTech, Colom 11, E-08222 Terrassa, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Vidal
authors.affiliation: ‡Group of Molecular and Industrial Biotechnology, Department of Chemical Engineering, Universitat Politècnica de Catalunya BarcelonaTech, Rambla Sant Nebridi, 22, 08222 Terrassa, Spain.
authors.forename: Tzanko
authors.initials: T
authors.lastname: Tzanov
authors.affiliation: †CELBIOTECH_Paper Engineering Research Group, Universitat Politècnica de Catalunya BarcelonaTech, Colom 11, E-08222 Terrassa, Spain.
authors.forename: M Blanca
authors.initials: MB
authors.lastname: Roncero
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D005707:Gallic Acid / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D042845:Laccase / Q000378:metabolism; D010084:Oxidation-Reduction
chemical_list: D005707:Gallic Acid; D002482:Cellulose; D042845:Laccase
keywords: alkyl gallates; cellulose; cyclic voltammetry; hydrophobicity; laccase