Synthesis of Hydrophobic\nand Antifouling Wood-Polymer\nMaterials through SI-ATRP: Exploring a Versatile Pathway for Wood\nFunctionalization

Wood is a highly durable material well suited for both\nresidential\nand commercial constructions and is a popular choice in furniture\nproduction. Enhancing its properties or introducing features, such\nas through functionalization with polymers, are highly desirable in\nthese industries. Thus, this article presents the grafting of poly(ethylene\nglycol) methyl ether methacrylate (POEGMA) and poly(<i>n</i>-butyl acrylate) (P<i>n</i>BA) from various types of wood\nfound in Europe (oak, walnut, cherry, larch, maple) and exotic wood\nspecies (merbau, jatoba). The grafting process utilizes the surface-initiated\nsupplemental activator and reducing agent atom transfer radical polymerization\n(SI-SARA ATRP) technique. The resulting block copolymers demonstrate\nantifouling properties derived from the POEGMA block, while the P<i>n</i>BA block imparts water-repellent characteristics. The controlled\nmanner of polymer grafting is evident through the linear kinetics\nand narrow molecular weight distribution of the formed polymers. Each\nstep of wood functionalization was confirmed by attenuated total reflectance\nFourier transform infrared (ATR-FTIR) and Raman spectroscopy, time-of-flight\nsecondary ion mass spectrometry (ToF-SIMS), and scanning electron\nmicroscopy (SEM) equipped with energy-dispersive X-ray spectroscopy\n(EDX). Surface morphology is further examined using a three-dimensional\n(3D) optical profilometer to determine the roughness parameters. Water\ncontact angle (Θ) measurements showcase the excellent hydrophobic\nproperties of the wood composite. The antifouling properties of POEGMA-functionalized\nsamples were confirmed by the determination of protein adhesion by\nfluorescence imaging and time-of-flight secondary ion mass spectrometry\n(ToF-SIMS) analysis. To imitate environmental factors that may affect\nthe structure of wood, the samples were immersed for 56 days in water\nand aqueous solutions of sulfuric acid (to simulate acid rain) and\nsodium chloride (to imitate the salinity level in the Baltic Sea,\n7‰), and then the absorption of the solutions was measured.\nAdditionally, protein adsorption and water contact angle tests were\nperformed on wood samples before and after being soaked in an aqueous\nNaCl solution. This study offers valuable insights for developing\nefficient and cost-effective wood-polymer composites with hydrophobic\nand antifouling properties through the chemical modification of the\nwood surface.