Influence of carboxymethylation on the surface physical–chemical properties of glucuronoxylan and arabinoxylan films

Abstract

Xylans were carboxymethylated in order to increase their anionic nature and thus tune their surface free energy (SFE) and hydrophilicity, which are of crucial importance in the majority of special applications. Fourier transform infrared spectroscopy and polyelectrolyte titration results confirmed the successful carboxymethylation of the xylan samples. The main aim of this study was to investigate the influences of carboxymethylation of glucuronoxylan and arabinoxylans on the surface physical and chemical properties of the films made from them. Films were prepared by the casting method, and their surface morphologies were analyzed by atomic force microscopy. The surface chemical compositions of the films were investigated using X-ray photoelectron spectroscopy, and their influences on SFE, i.e., Lifshitz-van der Waals and electron donor and acceptor contributions, were determined using goniometry. The introduction of 2 mmol/g of carboxyl groups into the glucuronoxylan or arabinoxylan molecular structures had a significant influence on the chemical and physical surface properties of the prepared films. Higher amounts of the carboxyl group present on the films' surfaces and higher surface roughness contributed to a significant increase (by 270%) in the electron donor component of SFE and to 40% improvements in the hydrophilicities of the films' surfaces. POLYM. ENG. SCI., 55:2706-2713

Syneresis in Gels of Highly Ferulated Arabinoxylans: Characterization of Covalent Cross-Linking, Rheology, and Microstructure

“…This analysis has revealed that the surface morphology slightly changed when the gel was formed at 1% or 2% ( w / v ) in AXs. It was observed that AX-1 gel showed a grained and irregular surface, while AX-2 gel presented a less grained and more regular surface without larger hollows or embossments as described before by Velkova et al [ 23 ] for AX films. Root mean square roughness ( R q ) values were 30.702 and 11.761 nm for the total surface of the AX-1 and AX-2 films, respectively, which confirms previous observations.…”

Development of carboxymethyl xylan films with functional properties

“…Its hydrophilic nature was given by the presence of carboxymethyl and hydroxyl groups in the CMX (Alekhina et al 2014). The value obtained was comparable to the CMX film without plasticizer produced by Velkova et al (2015). Regarding the other films, the contact angle increased when the CMX is incorporated with agar, AZC or linoleic acid in this order.…”

Influence of carboxymethylation on the gelling capacity, rheological properties, and antioxidant activity of feruloylated arabinoxylans from different sources

“…The absorption peaks at 1594 and 1418 cm −1 were assigned to C O stretching of the COO − ion, indicating the presence of new carbonyl groups within the carboxymethylated species. 43 Meanwhile, the absorption peak at 1324 cm −1 was assigned to C O stretching of the ─COO − ion or to the symmetric angular deformation of the C─H bond, which proves the presence of carboxymethyl groups. 43…”

“…43 Meanwhile, the absorption peak at 1324 cm −1 was assigned to C O stretching of the ─COO − ion or to the symmetric angular deformation of the C─H bond, which proves the presence of carboxymethyl groups. 43…”