2,5-Furandicarboxylate-based elastomer composites with surface-treated nanocellulose crystals: Toward engineering-plastic-level performance through efficient dispersion

This study develops a new bio-based elastomer nanocomposite with superior mechanical properties compared with other biomass-derived elastomers. This enhancement was achieved by optimizing the dispersion of surface-functionalized cellulose nanocrystals (CNCs), including sulfated (PCNC), carboxylated (ACNC), and silanized (SCNC). Their long-term dispersibility in 1,4-butanediol, a monomeric medium utilized for in situ polymerization was systematically assessed. Surface chemistry strongly influenced CNC compatibility with the polymer matrix, thereby governing interfacial interactions, crystallization behavior, and composite performance. Anionic CNCs (PCNC and ACNC) demonstrated the best uniform dispersion and minimized agglomeration during polymerization. The resulting poly(butylene-co-poly(tetramethylene ether glycol)furanoate) (PBPF) elastomers incorporating well-dispersed CNCs showed notable enhancements in tensile strength, elongation at break, and toughness. The optimal formulation, containing only 0.1 wt% ACNC with a 9:1 ratio of 1,4-butanediol to poly(tetramethylene ether glycol), achieved a tensile strength of 70.9 MPa and elongation at break of 713%, surpassing fully bio-based thermoplastic elastomers reported to date. These property enhancements were attributed to synergistic effects of phase-separated hard/soft domains and CNC-induced nucleation, as confirmed by morphological and thermal analyses. Overall, this work highlights the crucial role of CNC surface chemistry in dispersion and interfacial interactions, providing a scalable approach for developing sustainable and high-performance bio-based elastomers.