Dataset for ''Monovalent salt and pH-induced gelation of oxidised cellulose nanofibrils and starch networks: combining rheology and small-angle X-ray scattering''

Data collection method:

Rheological analysis: A stress-controlled rheometer (Discovery HR-3, TA Instruments, USA) equipped with a sandblasted plate-plate stainless steel geometry (40 mm) was used to perform the rheological tests at 25 °C, as described previously. Gels (approximately 0.7 mL) were placed in between the plates and frequency, amplitude sweeps and flow curves were measured (with a plate-plate gap of 0.5 mm). A thin layer of low viscosity silicone-oil was added to the edge of the geometry to prevent evaporation. Frequency sweeps were conducted, within the linear viscoelastic range, in strain control mode at 0.5% strain with an angular frequency range from 0.1 to 100 rad s-1. Amplitude sweeps were measured at an angular frequency of 1 Hz (6.28 rad s 1) covering the strain ranging from 0.5 to 50%. Finally, flow curves were measured to study the viscosity response of the sample to shearing, with a shear rate ranging from 0.01 to 100 s-1. Surface charge: Dilute suspensions (10 times dilution) of samples, using the appropriate buffer solution (DI water, NaCl or pH adjusted buffer) were used to measure the apparent ζ-potential utilising a Malvern Zeta-sizer Nano ZSP® (Malvern, UK). Samples were placed in the folded capillary electrode cell and were equilibrated at 25 °C for 120 s prior to testing. The data were taken from an average of 5 measurements from 100 scans each. Small-angle X-ray scattering (SAXS) analysis: SAXS measurements were conducted at Diamond Light Source (Didcot, Oxfordshire, UK), on the I22 beamline (using an X-ray wavelength of 1 Å corresponding to an energy of E = 12.4 keV) equipped with a PILATUS P3-2M detector (Silicon hybrid pixel detector, DECTRIS). Samples were loaded in glass capillary tubes (diameter~1.5 mm) and sealed. An empty capillary and the capillary containing DI water were also recorded for solvent subtraction. The probed q-range was 0.005–0.2 Å−1, where q is the scattering vector.

Data processing and preparation activities:

SASView software (version 4.1.2) was used to fit the SAXS data using either a rigid and flexible elliptical cylindrical model.