## 2 Results and Discussion
### Effect of TBAF Concentration on AVICEL(r) Chromatograms  
It has been proven that, in organic salts solvent systems, the concentration of the solid salt in the organic solvent can affect the cellulose dissolution. Indeed, [PERSON] et al. [34] demonstrated that the increase of LiCl content in LiCl/DMAc solutions improves cellulose dissolution. Considering this, several Avicel(r) samples in DMSO/TBAF have been prepared with different TBAF concentrations: from 2.5 mg/mL to 100 mg/mL. The obtained chromatograms are presented in Figure 3A. They demonstrated a strong influence of the TBAF concentration on the samples fractionation and hydrodynamic volumes. For the lowest TBAF concentration (2.5 mg/mL) the elution profile presented two different peaks. The first one was eluted inside the exclusion volume and accounted for more than 50% of the signal. The second one, at high elution volume, was relatively large. Increasing the TBAF concentration (5 mg/L, 10 mg/L and 20 mg/L) a symmetric peak appeared between 7.5 mL and 9.5 mL, for 10 mg/L and 20 mg/mL this peak was particularly well defined and reproducible. Increasing further the TBAF concentration (50 mg/mL and 100 mg/mL), the chromatograms showed a widened peak indicating a large hydrodynamic volume dispersion inside this sample. For a TBAF concentration of 100 mg/L, even a second peak appeared for high elution volume. Several hypotheses could explain these phenomena (Figure 3B). A too low TBAF concentration (below 5 mg/mL) does not seem to totally dissolve cellulosic chains, meaning one part of the sample may only be swollen. This swollen fraction, having a too high hydrodynamic volume to be retained in the column system, corresponds to the peak eluted in the exclusion volume as mentioned previously. Figure 2: Increase of hydrodynamic volumes of pullulan standards prepared with 5 mg/mL of TBAF. **(A)** High molecular weight samples; **(B)** low molecular weight samples. In ideal conditions, cellulose dissolution should be total, allowing a complete dissociation of polymeric chains, without influence of TBAF concentration on elution volumes. This seems to be the case for 10 mg/mL and 20 mg/mL, as both elution peaks were very similar. Finally, for higher concentrations (50 mg/mL and 100 mg/mL), the excess of TBAF molecules involved a dispersion on hydrodynamic volume, that may be related either to their aggregation on dissociated macromolecules, or to total disruption of the intramolecular hydrogen bonds leading to the complete unfolding of cellulosic chains. The molar mass obtained by conventional calibration with the calibration curve CC DT 0 confirms the phenomenon (Table 1). In case of Avicel\({}^{\circledR}\) samples dissolved with 2.5, 5, 50 and 100 mg/mL, the obtained molar masses were higher than the ones given by the suppliers or measured by viscosimetry [26]. On the contrary, the values obtained for the samples 10 mg/mL and 20 mg/mL are consistent with the reference ones, confirming that with such TBAF concentrations, the solvent system completely dissolves Avicel\({}^{\circledR}\), without any apparent modification of its hydrodynamic volume. Usually, the molar mass distribution determination using standard calibration curve requires working with the exact same dissolution conditions for both standards and samples. Accordingly, for the