A liquid marble was prepared from bio-based poly(lactic acid) [PLA] microparticles and water droplets.Solvent vapor exposure to the liquid marble changed the morphology of the granular PLA microparticle shell layer to a film-like shell layer even though the spherical shape of the liquid marble is retained. The morphological changes suppressed the evaporation of the water within the liquid marble by a factor of six compared with a liquid marble without the solvent vapor treatment. The compression test revealed that the mechanical stability of the solvent-treated liquid marble was changed due to the increased rigidity of the shell structure. Solvent vapor exposure is a simple but effective way to fabricate a robust liquid marble with long-term stability.
The surface properties of comb-shaped polymers with perfluorooctyl ethyl side-chains are strongly related to the ordered structure of the side-chains at the surface. In this work, the thermal behavior, liquidcrystalline structure, and functional group orientation of comb-shaped polymers containing perfluorooctyl side-chains with poly(acrylate) (PFA-C 8 ) and poly(vinyl ether) (PFAVE8) backbones are discussed based on DSC, synchrotron-source X-ray diffraction, and FTIR measurements. Despite the similar tilted hexatic smectic structures and packing entropies, the isotropization temperature, T i , of the PFA-C 8 is significantly higher than the PFAVE8. Detailed characterization of the conformation, alignment, and organization of the perfluorooctyl side-chains indicate that the difference in T i is related to the configuration of side-chains and interactions between the carbonyl groups along the acrylate backbone. The present findings show that the type of the linkage between the polymer backbone and fluorinated side-chain mesogens affects the conformation and plays an important role in determining thermal behavior.
The structure, thermal properties and surface wettability of a novel alternating poly(VCN-alt-FAVE8) copolymer based on vinylidene cyanide (VCN) and perfluorooctyl ethyl vinyl ether (FAVE8) were investigated via both temperature-variable wide-angle X-ray powder diffraction (WAXD) and thin-film WAXD using a small angle incidence synchrotron radiation source, differential scanning calorimetry and contact angle measurements, respectively. The results of the WAXD and thin-film WAXD indicated that the alternating copolymer possessed a smectic liquid-crystalline phase at ambient temperature with a couple of fluoroalkyl side chains forming a bilayer with a 3.24 nm spacing and that the fluoroalkyl side chains in a thin-film on a Si wafer align perpendicularly to the surface. The isotropization temperature of the alternating copolymer was 150 1C, which was higher than the 29.5 1C for the poly(FAVE8) homopolymer. The spin-coated poly(VCN-alt-FAVE8) copolymer thin-film yielded high static contact angles for both water and oil similar to those for poly(perfluorooctyl ethyl acrylate), which is known as a superhydrophobic polymer. Dynamic contact angle and X-ray photoelectron spectroscopy measurements in both the dry and hydrated states suggested that the polar cyano and ether groups are enriched at the surface in the wet state, and this reorganization of the surface polar groups caused a large hysteresis of the contact angle.
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