Fig. 2: Thickness and composition characterizations of PPM2.25.
From: Spontaneous water-on-water spreading of polyelectrolyte membranes inspired by skin formation
a Optical photographs of a PEI-PSSNa droplet spreading on pH 2.25 water; inner diameter of the glass vessel is 16 cm. Schemes are inserted to illustrate the cross-sectional changes of the droplet. b Thickness of PPM2.25 at seven different locations along the diameter direction. c Average thickness of PPMs prepared by SWOW on water with different pH. d Mole ratio of sulfur and nitrogen elements at different depth down the PPM2.25 cross-section. Error bars: standard deviation. Note: error bars in (b, c) are standard deviations. PP solution: PEI-PSSNa solution.
