Fig. 1: Characterization of the swelling and optical properties of polyvinyl alcohol thin films. | Nature Communications

Fig. 1: Characterization of the swelling and optical properties of polyvinyl alcohol thin films.

From: Tunable metasurfaces via the humidity responsive swelling of single-step imprinted polyvinyl alcohol nanostructures

Fig. 1

a Schematic of the molecular structure of polyvinyl alcohol (PVA). b Aqueous PVA solutions are created by dissolving (i) solid PVA powder into (ii) deionized water with concentrations of (iii) 3 and 5 wt%. All scale bars: 5 mm. c Schematic illustration of the swelling mechanism of PVA. As the relative humidity (RH) increases from (i) RH 45 to (ii) 80% the amount of H2O molecules absorbed into the hydrogel increase, leading to an increase in thin film thickness. d Measured thickness of PVA thin films spin-coated at 1000 (blue) and 3000 rpm (red) at various RH. e Measured and calculated refractive index of PVA at RH 45 and 80%, respectively. The refractive index of PVA at RH 80% is calculated using effective medium theory.

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