Lignin-methyl methacrylate polymer as a hydrophobic multifunctional material

Abstract

In this work, the modification of lignin (KL) with methyl methacrylate (MMA) is presented via free-radical polymerization in the presence of potassium persulfate as an initiator. One-step purification of the reaction products was also attested for generating KL-MMA with 95 wt% yield and 85 wt% MMA conversion. The characteristics of KL-MMA were studied comprehensively employing 1H NMR, 31P-NMR, 13C-NMR, SEM, FTIR, and GPC. KL-MMA demonstrated significantly higher thermal stability and UV absorption compared with unmodified KL and PMMA homopolymer. The hydrophobicity of lignin derivatives was substantially improved via reacting with acrylate monomer (a contact angle change from 25° for KL to 88° for KL-MMA). The performance of KL-MMA as an adsorbent for humic acid (HA) was also evaluated in detail by means of a Quartz crystal microbalance with dissipation (QCM-D). The results confirmed the superior adsorption performance of KL-MMA to that of KL and PMMA for HA. The modified lignin polymer possessed a multitude of excellent features including remarkable hydrophobic properties and adsorption capacity. The product offers a wide range of applications possibly in food packaging and water purification systems.