This Small Business Innovation Research (SBIR) Phase I project aims to develop a highly transparent, highly water-resistant (so called superhydrophobic) surface coating material, which is a solution that can be directly applied by users onto eye protective equipment in no more than two steps. Importantly, the material can be removed and re-applied without damaging the surface. In this project, an optimal formulation of the solution will be determined. The effects of surface morphology, and coating methods (e.g. dipping vs. spraying) on water repellency, transparency, and adhesion to plastic substrates that are typically used for eye protective equipment, will be studied. It is anticipated that the resulting coating material will be robust against regular buffing but removable using an appropriate solvent if desired for reapplication.
The broader/commercial impact of this project will be the potential to provide a simple and consumer-friendly coating that is both superhydrophobic and highly transparent for eye protective equipment, such as goggles, glasses, and eye shields. Potential follow-on applications include the coating of windshields, and other surfaces that also require a high degree of water resistance. Existing superhydrophobic coatings either are not very transparent, or require multiple application steps that are not user-friendly and could damage the surface being coated. Advances made through this project will have significant long-term safety and commercial impacts for consumer-applied superhydrophobic coatings.
The major goal of the Small Business Innovation Research (SBIR) Phase I project is to develop a renewable, highly transparent superhydrohpobic coating that can be applied and reapplied by consumers themselves on eye protective equipment, such as goggles, glasses, and eye shields, which are typically made of plastics. Water drops as small as 2 mm interfere with light, thus, limiting one’s vision quality. The ability to resist or remove all surface water is therefore highly desirable. Although there are several consumer-applied hydrophobic coatings for eye protective equipment, none of them are superhydrophobic (i.e. possessing a water contact angle ≥ 150o and a water droplet roll-off angle < 10o), and therefore do not remove all the water from one’s vision. Many superhydrophobic coatings developed in research stage and on market either are non-transparent, or require multiple steps before and after applying the coating, thus, making them undesirable as user-applied products or unsuitable for plastic substrates. In the SBIR Phase I period, we developed a new nanocomposite coating based on synergistic research activities, ranging from materials synthesis, formulation, processing, and structural characterization, which combined hydrophobic nanoparticles and hydrophobic polymer precursor in an all-in-one package. The mixed solution could be dip coated or spray coated on plastic substrates (e.g. polycarbonate) without sophisticated surface priming. Because the nanoroughness provided by nanoparticle assembly was no more than 100 nm, high transparency (> 95% transmittance) was achieved in the visible wavelength region. The combined hydrophobicity of the coating materials and the resulting nanoroughness via nanoparticle assembly offered superhydropobicity with an apparent water contact angle greater than 150o. On such surface, the water droplets could be easily shed off. The durability of the coating was improved by adding a hydrophobic polymer precursor, which acted as physical binders between the nanoparticles after thermal curing. To cover a large area, we developed a new spray coating formulation that was applicable to a wide range of substrates, including silicon, glass, epoxy, polycarbonate, and fabrics. Finally, we identified commercially available alternatives in the spray coating formulation, which significantly lowered the cost, making it a step closer for a viable consumer product. The broader impact of this project is the potential to bring to market a simple and consumer-friendly coating that is both superhydrophobic and highly transparent. It could potentially impact a broad range of markets that require wearing protective optics on the job while working outdoors, specifically, industrial safety, sports and military. Over many years, the quality, comfort and style of protective optics have improved dramatically. However, it remains challenging to develop a coating material that can be used outdoors in inclement weather and against water sprays or other flying debris yet maintaining high quality vision and robustness of the coating. Existing superhydrophobic coatings are not very transparent, or require multiple steps of surface pre-treatments, thus, limiting the adoption of the technology developed in research labs to do-it-yourself consumer products. Advances made through this project will have a significant long-term safety and commercial impact by enabling consumer-applied coatings with improved optical and surface performance. A partnership with an established hydrophobic coating supplier company on the protective eyewear has been developed through this project so as to expedite the commercialization of this developed technology into the marketplace. Markets beyond protective eyewear, for examples, packaging, electronics and energy efficient building and devices, are currently being explored.
