Hydrophobic surface functionalization of lignocellulosic jute fabrics by enzymatic grafting of octadecylamine

Abstract

Enzymatic grafting of synthetic molecules onto lignins provides a mild and eco-friendly alternative for the functionalization of lignocellulosic materials. In this study, laccase-mediated grafting of octadecylamine (OA) onto lignin-rich jute fabrics was investigated for enhancing the surface hydrophobicity. First, the lignins in jute fabrics were isolated and analyzed in the macromolecular level by MALDI-TOF MS, (1)H NMR, (13)C NMR, and HSQC-NMR. Then, the surface of jute fabrics was characterized by FT-IR, XPS, and SEM. Subsequently, the nitrogen content of jute fabrics was determined by the micro-Kjeldahl method, and the grafting percentage (Gp) and grafting efficiency (GE) of the enzymatic reaction were calculated. Finally, the surface hydrophobicity of the jute fabrics was estimated by contact angle and wetting time measurements. The results indicate that the OA monomers were successfully grafted onto the lignin moieties on the jute fiber surface by laccase with Gp and GE values of 0.712% and 10.571%, respectively. Moreover, the modified jute fabrics via OA-grafting showed an increased wetting time of 18.5 min and a contact angle of 116.72°, indicating that the surface hydrophobicity of the jute fabrics increased after the enzymatic grafting modification with hydrophobic OA molecules.

Laccase‐Mediated Grafting on Biopolymers and Synthetic Polymers: A Critical Review

“…Furthermore, extensive washing and rinsing with a good solvent (with respect to the amines) assured that any adsorbed material was washed off. Similar results were later found for the modification of jute fabrics with octadecylamine . The importance of extraction prior to laccase‐mediated modification was again exemplified because non‐extracted and unmodified jute exhibited SWCAs of 111°, due to the presence of lipophilic wax and fats.…”

“…These modest results indicate minimal grafting of acrylamide. Additionally, the initial SWCA of the jute proved to be exceptionally high (110°), which was likely to have been caused by contamination of the jute with fats and waxes . The presence of these compounds could also have influenced possible grafting, which makes these results hard to interpret.…”

“…Many of the materials discussed herein are of natural origin and could be contaminated with feculence or fats . Contaminants might shield the surface; thus hampering the intended grafting.…”

Plant Fibre: Molecular Structure and Biomechanical Properties, of a Complex Living Material, Influencing Its Deconstruction towards a Biobased Composite

“…The most common chemical treatments of fibres, improving the WPC performance, involve silane [290,291], maleic anhydride [292,293,294,295], mercerization [296,297,298] and acetylation [9,299,300]. To make the fibre more hydrophobic, several other types of treatment, such as permanganate [301], acrylation [302], isocyanate [303], benzoylation, fatty acid derivation (oleoyl chloride), enzymatic [235,304], fluorination [305], octadecylamine [306], PEI (polyethylene imine), CaCl 2 and Ca(OH) 2 have also been investigated. Some physical methods involving treatment by plasma [307], heat, corona, laser or γ-ray [308,309] have also been used and impact positively on the mechanical properties, such as stiffness, of the WPC.…”

Enzymatic Treatments to Improve Mechanical Properties and Surface Hydrophobicity of Jute Fiber Membranes

“…6b), probably because of the removal of cellulose by cellulase, as well as the enzymatic dislodgement and redistribution of bulgy lignins on the surface. The lignin removed from the jute surface at the beginning of the laccase treatment can polymerize and covalently reattach to the surface in the later stages of the reaction (Zhou et al 2013b;Dong et al 2015). In addition, cellulase/laccase-treated jute fiber membranes showed more combinations between jute short fibers, which indicated higher mechanical properties for the fiber membranes.…”