DOI: 10.15125/bath-01013
title: Dataset for "Salt-Responsive Pickering Emulsions Stabilized by Functionalized Cellulose Nanofibrils"

description: This data includes a variety of characterisation results for Pickering emulsions stabilised using either anionic TEMPO-oxidised cellulose nanofibrils or cationic cellulose nanofibrils functionalised with a quaternary ammonium group. The emulsions were prepared using sunflower oil either in water or solutions of NaCl to determine effects of fibril charge and salt concentration on the structures present in these emulsions, and how this related to their rheological properties.

Data included in this dataset are

AFM (02/2014): AFM measurements made by Yun Jin on OCNF at 0.8wt% (8gl ox-cell) and OCNF emulsions (beads+cellulose)(.jpg images and compressed text files from instrument)
CLSM (08/2018): CLSM measurements made by Julien Schmitt on OCNF and CCNF stabilised emulsions with 0; 0.1 and 0.5M NaCl. The folder is separated in subfolders, one subfolder per sample (images in .czi format)
Contact angle (2013): three series of contact angle measurements on CONF at the hexadecane/water interface made by Yun Jin (contains .jpg files for the images, and .xls files for analysis of the images)
Mastersizer - OCNF emulsions (2013): Mastersizer measurements made by Yun Jin on OCNF stabilised emulsions. The sub folder "salt effect" contains the measurements made for OCNF at various concentrations with 0; 0.1; 0.5 or 1 M salt (files .xslx; the .txt are the same data treated). The subfolder "pH effect" consists of measurements at pH=3; 5 or 11 at 0.8gL without salt (files .xls, and .tif for graphs).
Mastersizer - CCNF emulsions (2021): measurements made by Zakir Hossain at various pH for CCNF-stabilised emulsions at 1wt% (.xslx file)
Rheology (08-09/2018): Rheology measurements made by Julien Schmitt for dispersions (labeled "D_rheo") and emulsions ("E_rheo") stabilised by OCNF or CCNF at 1wt%. The folder is divided in 2 subfolders (OCNF and CCNF) one for each type of cellulose, while those are divided in 3 subfolders, corresponding to each type of measurement (viscosity, amplitude sweeps and frequency sweeps) Data is given in graphs as .pdf with the data also included as .txt files.
SANS (2019): SANS data for OCNF and CCNF dispersions at 1wt% but also emulsions with different salt concentration. A more complete description is given in the "description of SANS data.txt" file, in the folder. (Data and fit as .dat, .rds or .fit text files, graphed as .pdf or .jpg)
SEM (10/2013): SEM images (.tif files) made by Yun Jin on freeze-dried OCNF stabilised emulsion at 8gL
description: SEM
Freeze-dried emulsion (30 vol. % cyclohexane and 70 vol. % 8 g/L OCNF suspension) morphology was characterized using a scanning electron microscope (JEOL SEM6480LV or JEOL FESEM6301F, Japan) equipped with an energy dispersive X-ray spectrometer (Oxford INCA X-ray analyzer, UK) operating at an accelerating voltage of 5 or 10 kV.  Samples were coated with chromium or gold.

Mastersizer
Emulsion droplet sizes (Sauter diameter D(3,2)) were characterized using a Mastersizer X laser diffraction particle size analyzer (Malvern, UK) equipped with optics appropriate for detection of particle size in the 0.5-180 µm. Samples were measured in triplicate. 

Contact angle 
Water and hexadecane contact angles on spin-coated films of OCNF, produced from dispersions at pH 7.3 deposited and dried on glass slides, were determined using the sessile drop method at room temperature. Static images were captured using a Discovery VMS-001 USB microscope (Veho) and Dropsnake software with the ImageJ imaging process package to analyze images. Each measurement was conducted in triplicate.

Rheology
Rheology experiments were conducted on a Discovery HR-3 (TA instrument) in plate–plate geometry (40 mm diameter). The geometry was covered with a thin layer of mineral oil to avoid evaporation. Oscillatory strain experiments were conducted at 25 ◦C.  A pre-conditioning step of 20 s at zero-shear was applied before each measurement. Oscillatory frequency experiments were conducted at a strain of 0.5 %, within the linear viscoelastic regime. Finally, steady flow measurements were carried out for a shear rate ranging from 10-1 to 102 s-1.

Confocal microscopy
Emulsion droplets were also studied using an inverted confocal laser scanning microscope (CLSM) (ZEISS LSM 880, Germany) in the resonant mode with a 100× oil immersion objective. The emulsion suspension (6 µL) was sandwiched between the coverslips and hermetically sealed by a 120 µm thick spacer with a 5.1 mm aperture (SecureSeal Imaging). Before adding the solution, typically 40 µL of calcofluor white (from Sigma-Aldrich) was added to 1 mL of solution to allow imaging of the cellulose shell, since this dye fluoresces only when bonded to the cellulose nanofibrils.

Small angle neutron scattering (SANS)

Small angle neutron scattering (SANS) experiments were carried out at the Sans2d instrument at ISIS, Rutherford Appleton Laboratory, UK. The q range of the measurements was 0.0015 to 0.25 Å-1 and all experiments were conducted at 25°C. SANS with contrast variation was employed as a non-invasive technique to obtain structural information from the samples in-situ, based on scattering length density (SLD) differences.  Data were collected for five different sets of hydrogen and deuterium bearing components (for OCNF and CCNF, both hydrogenated): h-oil/D2O and d-oil/H2O give a full core-shell contrast for the droplets, d-oil/D2O allows scattering from the cellulose only, while h-oil/50%D2O is used to see the core of the droplets only. A last contrast, h-oil/70%D2O was used to confirm results obtained by the other contrasts. The samples were prepared less than a week prior to the SANS experiment. If creaming was observed, the upper phase was selected and pipetted into a 1 mm-thick SANS cell. All the SANS patterns acquired were checked for multiple scattering.
description: to view SEM, AFM, confocal images, contact angle images ImageJ can be used.
.xls and .xsls files require Excel to view.
SASView software (version 4.1.2) was used to fit some of the SAXS data using either a rigid and flexible elliptical cylindrical model.