(722ao) One-Step Functionalization of Cellulosic Nanowhiskers Using Renewable Reagents

Braun, B., Colorado School of Mines
Dorgan, J. R., Colorado School of Mines

Escalating fuel prices and increasing environmental concerns have sparked interest in materials based on renewable resources. Biopolymers have become attractive alternatives to oil-derived plastics, and research efforts are being made to further improve their properties thus making them suitable to a wider range of applications.

Composite formation is an effective approach to enhance mechanical and thermo-physical characteristics of polymers. Ideally, the rigid filler introduced into a biopolymer is also derived from renewables. Cellulosic nanowhiskers (CNW) can be isolated from various cellulose sources via controlled acid hydrolysis, and have been shown to be very efficient in improving mechanical properties. However, when they are to be incorporated into hydrophobic polymers their hydrophilic nature is problematic as it limits dispersion, ultimately leading to inferior reinforcement. The addition of surfactants or chemical alterations of the CNW surface are commonly employed strategies to address this issue; these approaches typically require multiple reaction steps.

Accessible hydroxyl groups can be functionalized in a new one-step chemistry in the presence of an acid catalyst. This one step method can be practiced simultaneously with the hydrolysis of amorphous cellulose regions to substitute a fraction of the surface hydroxyl groups on the resulting CNW. This renders the nanowhiskers more hydrophobic. Fourier-transform infrared spectroscopy in conjunction with multi-angle laser-light scattering for dimensional analysis allows determination of the average surface coverage. Consequently, the potential of these functionalized hydrophobic CNW as reinforcement for biopolymers to form nanocomposites is demonstrated.