Enzyme-mediated and formaldehyde-free formation of phenolic resin coatings

Abstract

Coatings from phenolic resins are utilized in a wide range of applications and remain a crucial type of thermosetting polymers. Curing at high temperatures and the utilization of formaldehyde, however, are ever more pressing concerns. In this work, a novel approach towards phenolic resin coatings is presented. The rationale follows the concept of Enzyme-Mediated Addressing, a technique for controlled formation of coatings and structures via immobilized enzymes. Employment of Horseradish Peroxidase leads to radical induced coupling of phenol to cross-linked polymers. This well-known polymerization technique is now performed at close proximity to the support surface. Action of the enzyme is shown to lead to formation of nanoparticles from poly phenolic material and their subsequent deposition on the surface. First, important reaction parameters are investigated. From this, largely coalesced films are gained at the ideal reaction conditions. Additionally, some insight into possible process mechanisms is provided. Finally, site-specific coatings are shown to be accessible with this method as well. Due to the applied enzymatic process, formaldehyde-free cross-linking at low temperatures is achieved.