3D finite element model of the cylindrical electrode geometry used in this study performed in pure water and for an applied potential of 1 V.

<p>A) equipotentials around a cylindrical electrode in a plane going through the centre of the cylinder. B) Electric field as a function of distance from the electrode surface taken along the two white lines in A). The solid line corresponds to the white line at the end of the electrode and the broken line corresponds to the white line perpendicular to the side of the electrode.</p

Growth of the gel phase around a bundle of silver platted copper wires immersed in a drop of 5.5wt% CNCs in water and held at 1 V.

<p>A) Radius of the gel phase (open symbols) and current between the two bundles (solid symbols) as a function of time. B) Radius of the gel phase as a function of time for different current forced between the two bundles.</p

Optical images with crossed polarizers of four different metal wires immersed in a drop of 5.5wt% CNCs in water.

<p>Each wire was held at a constant positive potential with respect to a bundle of silver plated wires not shown in the field of view. A) Copper wire held at 1 V for 10 min. B) Iron wire held at 1 V for 7 min. C) Gold wire held at 2 V for 1 min. D) Silver wire held at 5 V for 30 s. The position of the crossed polarizers is drawn in panel A. The scale bar is 300 µm.</p

Optical images with crossed polarizers of an iron wire held first at 1(Figure 1B) and then held at 2 V.

<p>A) 30 s after the potential was increased to 2 V. B) 90 s after the potential was increased to 2 V. The position of the crossed polarizers is drawn in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099202#pone-0099202-g001" target="_blank">Figure 1</a> panel A. The scale bar is 300 µm.</p

Growth of the gel phase around copper pads on a ITO substrate immersed in a drop of 0.5wt% CNCs in water and held at 1 V.

<p>A) square of copper before the experiment. B) Square of copper after 27 min. C) square of copper after 28 min. D) square of copper after 32 min imaged with crossed polarizers. E) Same as D) but the square was rotated by 45°. F) disk of copper after 7 min, the copper is still visible on the left side of the disk, arrowhead. The position of the crossed polarizers is drawn in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099202#pone-0099202-g001" target="_blank">Figure 1</a> panel A. The scale bar is 300 µm.</p

Optical images with crossed polarizers of a bundle of silver plated copper wires immersed in a drop of 5.5wt% CNCs in water and held at 1 V for A) 1 min, B) 5 min, C) 10 min.

<p>The position of the crossed polarizers is drawn in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099202#pone-0099202-g001" target="_blank">Figure 1</a> panel A. The scale bar is 300 µm.</p

Patterning of Nanocrystalline Cellulose Gel Phase by Electrodissolution of a Metallic Electrode

<div><p>At high concentration or in the presence of electrolytes and organic solvents, solutions of cellulose nanocrystals (CNCs) can form gels exhibiting optical properties similar to the ones of liquid crystal phases. In an attempt to pattern such a gel phase, we have studied the electrodissolution of a metallic electrode in a water suspension of carboxylated CNCs (cCNCs). Depending on the metal used, the electrodissolution process was observed at a different positive potential. In the case of copper the minimum potential at which we could observe optically the growth of the gel phase was 200 mV. The growth rate was current limited indicating that the process was controlled by the electrodissolution of the copper electrode. This hypothesis was confirmed by using circular and square copper patterns as positive electrodes. In both cases, the consumption of the electrode material was observed optically and correlated with the growth of the gel phase.</p></div

Growth of the gel phase around a bundle of silver plated copper wires immersed in a drop of 5.5wt% CNCs in water and held at different potentials from 0.2 to 1.2 V.

<p>A) radius of the gel phase as a function of time for each applied potential. B) Average growth velocity as a function of applied potential for the first 30 s (solid symbols) and after (open symbols).</p