In the present work, we developed eco-friendly and cost-effective nanocomposite coatings. These wax-derived coatings showed high superhydrophobicity while exhibiting mechanical and thermal robustness. The addition of nano-alumina particles in wax (Beeswax and Paraffin) significantly enhanced de-wetting (contact angle ~ 156°) with extremely low hysteresis (&lt;5°). The Paraffin-based composite coating showed better thermal (up to 50 °C) and mechanical (Δθ≈5°) (droplet impacts) stability than Beeswax counterpart, while also sustaining outdoor exposure. The superhydrophobic coatings showed self-cleaning ability with significantly low water consumption (&lt;1 μl/mm2). We showed that nanocomposite-wax coatings possess required durability and are potential candidates for developing non-fluorinated self-cleaning surfaces. © 2020 Elsevier B.V.

Harpreet Singh

Mechanical Engineering

(SoE) School of Engineering

Harpreet Singh Grewal

Gupta S.

Babu A.

<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

Materials Letters

Surface modification is a promising method to solve the tribological problems in microsystems. To modify the surface, we fabricated hierarchical patterns with different pitches of nano-scale features and different surface chemistries. Micro- and nano-patterns with similar geometrical configurations were also fabricated for comparison. The nano-tribological behavior of the patterns was investigated using an atomic force microscope at different relative humidity levels (5\% to 80\%) and applied normal loads (40 nN to 120 nN) under a constant sliding velocity. The results showed significant enhancement in the de-wetting and tribological performance of the hierarchical patterns compared with those of flat and micro- and nano-patterned surfaces. The PTFE-coated hierarchical patterns showed similar dynamic contact angles (advancing and receding) to those of the real lotus leaf. The influence of relative humidity on adhesion and friction behavior was found to be significant for all the tested surfaces. The tribological performance was improved as the pitch of the nano-scale geometry of the hierarchical pattern increased, even though the wetting property was not influenced significantly. A model was proposed based on the role of intermolecular force to explain the effect of the pitch of the hierarchical patterns on the adhesion and friction behavior. According to the model based on the molecular force, the contact between a ball and the patterned surface was a multi-asperity contact, contrary to the single-asperity contact predicted by the Johnson-Kendall-Roberts (JKR) and Maugis-Dugdale (MD) models. The strong intermolecular forces, which are activated in the confined spaces between the adjacent nano-pillars and the ball, contributed to the contact area and hence the adhesion and friction forces. © The Royal Society of Chemistry 2016.

Fulltext

Soft Matter

Nanotribological and wetting performance of hierarchical patterns

Advanced Materials Interfaces

Engineering Fully Organic and Biodegradable Superhydrophobic Materials

Fabrication of self-healing waterbased superhydrophobic coatings from POSS modified silica nanoparticles

Journal of Colloid and Interface Science

Superhydrophobic coatings with high repellency to daily consumed liquid foods based on food grade waxes

ACS Nano

Nanomanufacturing: A Perspective

High durability of non-fluorinated superhydrophobic nanocomposite coatings