Stability and controlled dewetting of polymer thin films have practical, technological, and fundamental significance. The studies of polymer thin films prepared from aqueous solution have been limited due to the particular challenges involved in elucidating the effects of drying dynamics and solvent polarity on thin film stability. In this research, poly(vinyl alcohol) (PVOH) thin film dewetting on silicon wafer-supported polydimethylsiloxane (PDMS) is studied by the new adsorptive spin casting method, allowing the spontaneous adsorption of PVOH at the PDMS-solution interface and the generation of ordered PVOH dewetting patterns by directional drying. PVOH is chosen because of its tunable crystallinity allowing the study of a range of dewetting morphologies from conventional droplets to structures with unique fractal features; silicon wafer-supported PDMS is the substrate of choice permitting the probe of substrate mobility and polarity. Emphases is placed on how fractal morphology in terms of fractal dimension and lacunarity is affected by various experimental parameters, such as adsorption/contact time, PVOH concentration, molecular weight and degree of hydrolysis, drop size, substrate mobility, and spin rate using the adsorptive spin casting method. Ordered morphologies are produced within a confined drop as the outcome of directional drying in a circular geometry and in the runoff region as the outcome of directional drying in a linear geometry. Results from the adsorptive spin casting method will be compared to those obtained using the conventional immersive adsorption method and advantages of the former will be highlighted in the presentation.

Polymer ultrathin films: Preparation, stability, and morphology

256th National Meeting (2018)

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