Surfactant-modified cellulose nanofiber reinforcement in polyfarnesene-based (Bio)rubber composites

This study investigates the reinforcement of rubber biocomposites by incorporating surfactant-modified cellulose nanofibers. (Bio)rubbers based on Polyfarnesene, Polybutadiene, and a Polyfarnesene-Polybutadiene copolymer (with a composition of 35 % PFa and 65 % PB) were produced, reinforcing them with TOCNFs modified via physisorption, using different cationic surfactants. Molecular dynamics simulations provided insights into the interactions between surfactants and CNFs, revealing that Trimethylphenylammonium Chloride (TPACl) facilitated stronger interfacial bonding potentially due to π–π interactions, which also showed the best compatibilization reflected in terms of rubber performance. The optimal CNF loading was determined to be around 3 wt%, beyond which aggregation negatively impacted properties. In the PFa matrix, mechanical testing revealed significant improvements in tensile strength (up to 20 %), elongation at break (enhanced by 80 %), and notably the Youngs Modulus (up to 2100 % improvement). Dynamic mechanical analysis showed enhanced storage and loss moduli, indicating increased stiffness and energy dissipation. This study uniquely combines surfactant-modified CNFs with bio-based rubber matrices (PFa/PFa-co-PB), demonstrating mechanical enhancements via optimized interfacial design. • Surfactant-modified TEMPO-oxidized cellulose nanofibers (CNFs) were incorporated into bio-based rubbers. • Simulations revealed that TPACl surfactant promotes strong π-π interactions, enhancing CNF-matrix interaction. • An optimal CNF loading of 3 wt% was identified, yielding remarkable improvements in mechanical properties. • Surfactant type influenced crosslink density and mechanical behavior.