Synthesis of Hydrophobic and Antifouling Wood-Polymer Materials through SI-ATRP: Exploring a Versatile Pathway for Wood Functionalization

Wood is a highly durable material well suited for both residential and commercial constructions and is a popular choice in furniture production. Enhancing its properties or introducing features, such as through functionalization with polymers, are highly desirable in these industries. Thus, this article presents the grafting of poly(ethylene glycol) methyl ether methacrylate (POEGMA) and poly(n-butyl acrylate) (PnBA) from various types of wood found in Europe (oak, walnut, cherry, larch, maple) and exotic wood species (merbau, jatoba). The grafting process utilizes the surface-initiated supplemental activator and reducing agent atom transfer radical polymerization (SI-SARA ATRP) technique. The resulting block copolymers demonstrate antifouling properties derived from the POEGMA block, while the PnBA block imparts water-repellent characteristics. The controlled manner of polymer grafting is evident through the linear kinetics and narrow molecular weight distribution of the formed polymers. Each step of wood functionalization was confirmed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) and Raman spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). Surface morphology is further examined using a three-dimensional (3D) optical profilometer to determine the roughness parameters. Water contact angle (Θ) measurements showcase the excellent hydrophobic properties of the wood composite. The antifouling properties of POEGMA-functionalized samples were confirmed by the determination of protein adhesion by fluorescence imaging and time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis. To imitate environmental factors that may affect the structure of wood, the samples were immersed for 56 days in water and aqueous solutions of sulfuric acid (to simulate acid rain) and sodium chloride (to imitate the salinity level in the Baltic Sea, 7‰), and then the absorption of the solutions was measured. Additionally, protein adsorption and water contact angle tests were performed on wood samples before and after being soaked in an aqueous NaCl solution. This study offers valuable insights for developing efficient and cost-effective wood-polymer composites with hydrophobic and antifouling properties through the chemical modification of the wood surface.