title: Effect of spatial distribution of wax and PEG-isocyanate on the morphology and hydrophobicity of starch films.
abstract: This study proposes a novel method for improving surface hydrophobicity of glycerol plasticized high amylose (HAG) films. We used polyethylene glycol isocyanate (PEG-iso) crosslinker to link HAG and three natural waxes (beeswax, candelilla wax and carnauba wax) to produce HAG+wax+PEG-iso films. The spatial distributions of wax and PEG-iso across the thickness of these films were determined using Synchrotron-based Fourier transform infrared spectroscopy. The hydrophobicity and surface morphology of the films were determined using contact angle (CA) and scanning electron microscopic measurements, respectively. The distribution patterns of wax and the PEG-iso across the thickness of the film, and the nature of crystalline patterns formed on the surface of these films were found to be the key factors affecting surface hydrophobicity. The highest hydrophobicity (CA >90°) was created when the PEG-iso was primarily distributed in the interior of the films and a hierarchical circular pinnacle structure of solidified wax was formed on the surface.
authors.affiliation: School of Health Sciences, University of Ballarat, VIC 3353, Australia.
authors.forename: Delina
authors.initials: D
authors.lastname: Muscat
authors.affiliation: Materials Science and Engineering, CSIRO, Clayton South, VIC 3169, Australia.
authors.forename: Raju
authors.initials: R
authors.lastname: Adhikari
authors.affiliation: IR Beamline, Australian Synchrotron, Clayton, VIC 3168, Australia.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Tobin
authors.affiliation: School of Science, Information Technology & Engineering, University of Ballarat, VIC 3353, Australia.
authors.forename: Stafford
authors.initials: S
authors.lastname: McKnight
authors.affiliation: School of Health Sciences, University of Ballarat, VIC 3353, Australia.
authors.forename: Lara
authors.initials: L
authors.lastname: Wakeling
authors.affiliation: School of Applied Sciences, RMIT University, Melbourne City Campus, VIC 3001, Australia. Electronic address: benu.adhikari@rmit.edu.au.
authors.forename: Benu
authors.initials: B
authors.lastname: Adhikari
mesh_terms: D005780:Gelatin / Q000737:chemistry* / Q000648:ultrastructure; D057927:Hydrophobic and Hydrophilic Interactions; D017953:Isocyanates / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry; D013213:Starch / Q000737:chemistry*; D014885:Waxes / Q000737:chemistry*
chemical_list: D017953:Isocyanates; D014885:Waxes; C015233:gelatin film; C038228:beeswax; D011092:Polyethylene Glycols; D005780:Gelatin; D013213:Starch; C026344:carnauba wax
keywords: Amylose; Hydrophobicity; Hydroxyl-PEGylation; Natural wax; Surface morphology; Synchrotron-based FTIR