Dataset for "Alcohol induced gelation of TEMPO-oxidized cellulose nanofibril dispersions"

Data collection method:

Rheological measurements were conducted on a stress-controlled Discovery Hybrid Rheometer, Model HR-3 (TA Instruments, USA) equipped with a crosshatched 20 mm parallel plate geometry over a sandblasted lower plate. Temperature was controlled via a Peltier unit (±0.1 °C). A thin layer of low viscosity silicon-oil was added to the edge of the geometry to prevent evaporation. Oscillatory frequency sweeps were conducted at strain (γ) of 0.5% covering the angular frequency of 50 to 0.01 rad/s (Fig 1 and 2 sets) . Flow curves were measured from shear rates of 0.01 to 10 1/s . All experiments were conducted at 25 °C (Fig 3 sets). Scanning Electron Microscope (SEM) images of cellulose aqueous and alcoholic dispersions (0.8 wt%) were obtained using a JEOL JSM6480LV SEM (Jeol, USA) at 10 kV. Aqueous dispersions were freeze-dried, mounted on adhesive carbon tape and gold sputter-coated prior to imaging of the fibrils. The alcohol dispersions in methanol (100 %) or ethanol (100 %) were sliced into 2 x 2 cm squares, critical point dried from the alcohol and sputter-coated with gold (Fig 4 set). Small-angle X-ray scattering (SAXS) measurements were conducted at the Diamond Light Source beamline I22 using a PILATUS 2 M (Dectris, Switzerland) detector. The X-ray wavelength used was 1 Å, corresponding to an energy of 12.4 keV, and the accessible q-range was 0.006 to 0.6 1/Å. Data were reduced, and solvent and capillary contributions were subtracted using the Dawn software. Experiments were conducted at room temperature (Fig 5 sets).

Data processing and preparation activities:

The SAXS data (Figure 5 set) were fitted using a model of interacting rigid cylinders with elliptical cross sections and uniform scattering length density. The fitting parameters for the form factor of the fibrils are the major and minor radii of the cross-section of the cylinders, Rmax and Rmin respectively, and the length of the fibrils, L. Polydispersity of the cross section was not modelled. The effect of interactions on the scattering was calculated using the PRISM model, with the parameter νRPA , proportional to the concentration of cylinders, describing the strength of the interactions between the cylinders (the local excluded volume radius around each site being neglected for weak interactions).

Methodology link: