Laccase-Mediated Grafting of Phenolic Compounds onto Lignocellulosic Flax Nanofibers

ABSTRACT

Lignocellulosic nanofibres (LCNF) are nanometer additives that can be used to improve the mechanical, esthetical, optical and thermal properties of polymers in composites, packages, or coatings. Surface modification of these hydrophilic nanometer additives is needed to improve their properties and applicability in hydrophobic polymers matrix. In this work, two phenolic monomers, guaiacol and syringaldehyde were for the first time, efficiently grafted onto the exposed residual lignin of lignocellulosic nanofibres surface by a laccase from Trametes versicolor mediated reaction. Guaiacol grafted (LCNFG) and syringaldehyde grafted (LCNFS) lignocellulosic nanofibres were characterized with Fourier Transform Infra-Red (FTIR) and UV–visible techniques. Thermal and hydrophobic properties were analyzed by thermogravimetric analysis (TGA) and Water contact angle (WCA) measurements. FTIR analyzes confirmed the laccase mediated grafting of guaiacol and syringaldehyde onto lignocellulosic nanofibres. UV–visible gave evidence for the grafting of phenolic entities onto lignocellulosic nanofibres by factual data supporting experimental observations, leading to brown and orange colored grafted lignocellulosic nanofibres (LCNFG and LCNFS, respectively). TGA has shown that grafting of phenolic compounds endowed LCNF better thermal stability. WCA angle and wettability measurements showed that the surface hydrophobicity of LCNFG and LCNFS was increased after the enzymatic grafting modification.

摘要

木质纤维素纳米纤维（LCNF）是一种纳米添加剂，可用于改善复合材料、包装材料或涂层中聚合物的力学、美学、光学和热性能. 这些亲水性纳米添加剂需要进行表面改性，以提高其在疏水性聚合物基体中的性能和适用性. 本文首次将愈创木酚和丁香醛这两种酚类单体通过云芝漆酶介导的反应，有效地接枝到木质纤维素纳米纤维表面裸露的残余木质素上. 采用傅立叶变换红外光谱（FTIR）和紫外可见光谱（UV-可见）对愈创木酚接枝（LCNFG）和丁香醛接枝（LCNFS）木质纤维素纳米纤维进行了表征. 通过热重分析（TGA）和水接触角（WCA）测定分析了其热性能和疏水性能. FTIR分析证实了漆酶介导的愈创木酚和丁香醛在木质纤维素纳米纤维上的接枝反应. UV-可见通过支持实验观察的事实数据为酚类物质接枝木质纤维素纳米纤维提供了证据，导致棕色和橙色接枝木质纤维素纳米纤维（分别为LCNFG和LCNFS）. 热重分析表明，酚类化合物的接枝使LCNF具有较好的热稳定性. WCA角和润湿性测试表明，酶接枝改性后LCNFG和LCNFS的表面疏水性增强.

KEYWORDS:

• Lignocellulosic nanofibers
• biografting
• laccase
• hydrophobization
• guaiacol
• syringaldehyde

关键词:

• 木质纤维素纳米纤维
• 生物漂流
• 漆酶
• 疏水化
• 愈创木酚
• 丁香醛

Acknowledgments

The authors gratefully acknowledge the Natural Sciences and Engineering Research Council of Canada who provided funds for this research.

Additional information

Funding

This work was supported by the Natural Sciences and Engineering Research Council of Canada.