Preparation of Renewable Thiol‐Yne “Click” Networks Based on Fractionated Lignin for Anticorrosive Protective Film Applications

Abstract

The synthesis of novel, renewable lignin-based protective films with anticorrosive properties is presented in this work. Thermosetting films are prepared by means of tandem UV-initiated thiol-yne "click" synthesis and Claisen rearrangement strategy. These films contain high lignin loading, 46-61%, originating from a nickel-catalyzed birch wood reductive catalytic fractionation (RCF) process. Lignin fractions with varying monomer content are compared before resins preparation, namely a mixture of monomers and oligomers without fractionation, or after fractionation via extraction and membrane separation. This study aims to determine if the separation of lignin monomers and oligomers is necessary for the application as a thermosetting resin. The resulting films exhibit remarkable adhesion to a metal surface and excellent solvent resistance, even after exposure to a corrosive environment. Moreover, those films show superior barrier properties, studied with odd random phase electrochemical impedance spectroscopy (ORP EIS). After 21 days of exposure, the examined films still show impressive high corrosion protection with the low-frequency impedance ≈10 10 𝛀 cm 2 and capacitive behavior. This work demonstrates an interesting proof-of-concept where laborious, costly, and energy-intensive separation of the depolymerized lignin mixture of monomers and oligomers is not necessary for the successful resin synthesis with excellent properties using the applied synthetic strategy.

Stepping away from purified solvents in reductive catalytic fractionation: a step forward towards a disruptive wood biorefinery process

“…, phenol, 54,55 propylene, 55 ethylene glycol 56,57 ), polymers ( e.g. , polycarbonate, 58 polyurethanes, 52 epoxy resins 59,60 ), coatings, 61 adhesives ( e.g. , epoxy resin 62 ), antioxidants, 63,64 surfactants, 25 etc.…”

“…[46][47][48][49] This reactor configuration allowed to study the kinetics of the main reaction steps viz., solvolysis, reductive stabilization and recondensation independently, leading to a better understanding of the inherent relations between mass transfer and chemical reaction in RCF. 30,50 The main products of the RCF biorefinery, the carbohydrate pulp and lignin oil are excellent precursors for multiple chemical products like fuels (e.g., ethanol, 17 naphtha, 51 jet fuel 52,53 ), platform chemicals (e.g., phenol, 54,55 propylene, 55 ethylene glycol 56,57 ), polymers (e.g., polycarbonate, 58 polyurethanes, 52 epoxy resins 59,60 ), coatings, 61 adhesives (e.g., epoxy resin 62 ), antioxidants, 63,64 surfactants, 25 etc. This signifies the large valorisation potential of lignocellulose biorefining with RCF.…”

The Covalent Linking of Organophosphorus Heterocycles to Date Palm Wood-Derived Lignin: Hunting for New Materials with Flame-Retardant Potential

“…Butanosolv lignin is highly suited to selective covalent modification as it is soluble in most organic solvents enabling the use of standard reaction sequences. For example, butanosolv (and other) lignins have been used as substrates for grafting on small molecules using click chemistry [22,26,27]. Increasingly, researchers are interested in enhancing the inherent flame-retardant properties of lignin through its covalent modification with OPFRs.…”