Biomimetic nanosurfaces with distinct wettability and versatility have found special enthusiasm in both fundamental research and industrial applications. With the advent of nanotechnology, it is doable to acclimate surface architecture and surface chemistry to attain superhydrophobicity. The uniqueness of superhydrophobic surfaces arises from various phenomenal advances, and its progress is expected to continue for decades in the future. In this Review Article, we discuss recent progress made in defining physical aspects of numerical modeling, experimental practices adopted, and applications of superhydrophobic surfaces. First, we revisit various classical models of superhydrophobicity and recent theoretical advances achieved related to the wetting phenomena. Subsequently, we emphasize various precursors and advance fabrication strategies adopted to fabricate superhydrophobic surfaces. In the following section, we take up various potential applications and appropriate working principles to explain wettability phenomena. Finally, some general conclusions are drawn along with proposed guidelines for designing robust superhydrophobic coatings.

Titanium dioxide (TiO2) nanoparticle decorated [poly­(4-methylstyrene-co-divinylbenzene)] microcapsules enclosing phase change material (PCM) were synthesized following a one-pot non-Pickering emulsion templated suspension polymerization. TiO2 nanoparticles were hydrophobized using a trace amount of tertradecyltrimethylammonium bromide (TTAB, cationic stabilizer) through electrostatic interaction and employed as a particle stabilizer. The resulting microcapsules presented concurrent functionalities of thermal energy storage and photocatalytic activity. Scanning electron microscopy (SEM) identified that microencapsulated PCMs (microPCMs) exhibited a well-defined, core–shell structure with spherical morphology. The existence of TiO2 over the polymeric shell was confirmed by energy-dispersive X-ray (EDX) and X-ray diffraction (XRD) analysis. Differential scanning calorimetry (DSC) analysis demonstrated that microPCM with 2.6 wt % TiO2 achieved maximum phase change enthalpy of 174 J/g with an encapsulation efficiency of 76.6% and could maintain it even after 100 melting–freezing cycles. Thermogravimetric analysis (TGA) revealed that the addition of TiO2 contributed in improving the thermal stability of microPCMs. Most of all, the produced microcapsules exhibited great photocatalytic activity through the synergistic photothermal effect. The bifunctional microcapsules reported in this work would stimulate wide applications in the biomedical field, residential buildings in polluted urban sites, and industrial establishments as thermal energy storage and depollution materials.

Microencapsulation of lauryl alcohol (1-dodecanol; mp, 22 ± 0.3 °C; melting enthalpy, 191 ± 3 J/g), a renewable phase change material (PCM), was carried out using copolymer shell [poly(styrene-co-n-butyl acrylate-co-divinylbenzene) or p(Styco-BA-co-DVB)] synthesized adopting emulsion polymerization. The thermal buffering ability of microencapsulated phase change material (MEPCM) was evaluated after embedding these capsules in a poly(vinyl chloride) (PVC) film. Spectroscopic (FT-IR) and morphological characterization of MEPCM capsules and MEPCM-embedded PVC film (MEPCM ePVC) confirmed the formation of core−shell microstructure with just physical interaction between PCM and shell. Differential scanning calorimetry (DSC) measurements confirmed effective encapsulation of core inside the p(Sty-co-BA-co-DVB) shell, and the latent heat of melting of capsules was in the range between 94 ± 3 and 133 ± 3 J/g. Thermogravimetric analysis (TGA) measurements supported the data of PCM content measured from DSC. A polarized optical microscope with hot stage established nonleaking behavior with MEPCM ePVC when exposed to 50 °C. The thermal buffering ability of the MEPCM ePVC film was demonstrated based on 41.9 and 224.8% delays in temperature change during charging and discharging steps, respectively, compared to the performance with pristine PVC film wrapped over a box of specific dimension.

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