Molecular Design of Lignin-Derived Side-Chain Phenolic Polymers toward Functional Radical Scavenging Materials with Antioxidant and Antistatic Properties

Abstract

This article reports a new family of functional side-chain phenolic polymers derived from lignin monomers, displaying a combination of properties that are usually mutually exclusive within a single material. This includes a well-defined molecular structure, transparency, antioxidant activity, and antistatic properties. Our design strategy is based on the lignin-derived bioaromatic monomer dihydroconiferyl alcohol (DCA), a promising and yet largely unexplored asymmetrical diol bearing one aliphatic and one phenolic hydroxyl group. A lipase-catalyzed (meth)acrylation protocol was developed to selectively functionalize the aliphatic hydroxy group of DCA while preserving its phenolic group responsible for its radical scavenging properties. The resulting mono-(meth)acrylated monomers were then directly copolymerized using reversible addition-fragmentation chain-transfer (RAFT) polymerization without any protection of the phenolic side chains. Kinetics studies revealed that, under select conditions, these unprotected phenolic groups surprisingly did not inhibit the radical polymerization and lead to polymers with defined molar masses, low dispersities, and block copolymers. Finally, applications of these new radical scavenging polymers were demonstrated using an antioxidant assay and antistatic experiments. This research opens the door to the direct incorporation of natural antioxidants within the synthetic polymer backbones, increasing the biobased content and limiting the leaching of potentially harmful additives.

Bioaromatic-Associated Multifunctionality in Lignin-Containing Reversible Elastomers

“…Consequently, the addition of antioxidants that trap or annihilate radicals might result in an indirect way of creating an antistatic material, as already indicated in the literature . As described above, the lignin-containing networks show antioxidant activity due to the presence of phenolic OH and thus should contribute to an antistatic effect. , …”

Core–Shell Quantum Dot-Embedded Polymers for Antistatic Applications

“…The polymer bonds break upon mechanical input of contact and separation, creating mechanoions on the polymer surfaces. − Mechanoions are stable charged species and can exchange electrons with the surrounding chemical species. This exchange can be facilitated with molecular or polymeric organic compoundsdiphenyl picrylhydrazyl, tocopherol, polydopamine, tannic acid, and lignin − embedded into the polymers to scavenge mechanoradicals and to destabilize the charges. The low doping amounts (a few percent) are needed to attain the antistatic behavior, and the retainment of electrical, physical, and mechanical properties is an advantage provided by this method.…”