Injection Molding of Superhydrophobic Submicrometer Surface Topography on Macroscopically Curved Objects: Experimental and Simulation Studies AITranslate

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DOI：https://doi.org/10.1021/acsapm.9b00312

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Micro- and nanoscale surface topographies that give rise to superhydrophobic surfaces have been achieved mostly on 2-dimensional planar objects. Increasing interests in superhydrophobic surfaces on consumer products, optics, and biomedical devices demand topographic patterning on free-form nonplanar surfaces via a high throughput manufacturing process such as injection molding. However, successes in high-resolution (submicrometer) injection molding have been limited to flat and planar objects. A challenge associated with achieving submicrometer surface resolution on a 3-dimensional curved object lies in the control of the replication process in a multiscale mold cavity and the nonuniform temperature and pressure distribution over a macroscopically curved mold insert. Here, a two-step simulation approach is employed to investigate the replication of polymer in the macroscopic and submicrometer cavities. Both simulation and experimental data revealed the effects of holding pressure, mold temperature, and macroscopic curvature on polymer filling percentage and replication uniformity over the entire curved surface. Injection-molded PP with macroscopic curvature and submicrometer surface pattern has been achieved with a high yield and pattern uniformity above 95%. The superhydrophobic property, specifically, spontaneous dewetting of water droplet on curved PP, was demonstrated on anisotropic 300 nm grating and isotropic 250 nm pillar structures. The results presented here can be adopted for development and rapid prototyping of 3-dimensional complex-shaped polymers with superhydrophobic surface topography.