Sustainable alliance between nanocellulose and biobased polyfurfuryl alcohol

Furfuryl alcohol is amongst the top platform chemicals within a modern biorefinery and is widely used for poly (furfuryl alcohol) (PFA) synthesis. Nanocellulose addition to PFA can yield to the production of fully biomass-derived nanocomposite thermosets with improved thermomechanical properties. However, limited studies have been conducted due to cellulose's hydrophilic nature and its incompatibility with polymer substrates. This study shows the successful incorporation of cellulose nanofibers and nanocrystals in the PFA matrix, in 4 different loading levels for each type of additive. Microscopy observations were employed to determine cellulose's dispersion into the polymer substrate, while the composites’ thermal properties were slightly improved. A remarkable increase of the glass transition temperature (T_g) up to 30 °C was noted for all composite materials, compared to neat PFA. In particular, the storage modulus in the rubbery state is significantly higher when the loading level of cellulose is above 0.5 wt%. Finally, it was found that FA polymerization in aqueous conditions can enhance the formation of carbonyl species through furan opening reactions, thus allowing more cellulose hydroxyls to interact with the polymer matrix.