Fabrication of superhydrophobic surface by a dimensional change in surface topography of microchannel on polymer substrate through induction-aided hot embossing: parametric investigation and optimization

Hot embossing (HE) is a micro-fabrication technique employed to create micron-scale patterns on the polymer substrate. An in-house induction-assisted hot embossing (IHE) setup was fabricated to complete the embossing in a short duration as compared to traditional hot embossing process. This work alters the polymer surface topography to make it super hydrophobic for self-cleaning. Fiber laser machining was used to produce four-microchannel designs on an Aluminum-6061 plate in which the microchannel width was varied from 600 mu m to 150 mu m while maintaining a constant adjacent distance of 300 mu m. This textured plate is employed as a mold in the IHE setup. IHE process parameters, embossing temperature, pressure, time, and deem bossing temperature were varied to emboss the mold designs on a polyethylene terephthalate substrate. Thereafter, the embossed microchannel height, surface roughness, and water contact angle perpendicular to the embossed microchannels (WCA(perpendicular to)) were calculated. The parametric analysis examined how operational factors affected the output. The experiment was done as per the central composite design (experimental design) part of the design-of-experiments useful in the response surface model. Parametric research demonstrates that embossed microchannel height and width had a maximum effect on WCA(perpendicular to). Type IV microchannels with 150 mu m width demonstrated the highest WCA(perpendicular to). The WCA(perpendicular to) was mostly impacted by embossed microchannel height; hence a regression model was created using type-IV channel height data. Analysis of variance showed that embossing temperature mainly impacts microchannel height. The recently invented Jaya-algorithm optimized this model to increase embossed microchannel height and WCA(perpendicular to). Setting the parameters at the best level predicted by Jaya algorithm yielded an embossed microchannel height inaccuracy of 2.18%. The WCA(perpendicular to) measured on the surface of a sample prepared at the best parameters was found to be 154.71 degrees +/- 2 degrees. Lastly, FTIR (Fourier-transform-infrared-spectroscopy) test showed no chemical composition change between the embossed and bare samples.