Recently, there has been much progress in the design and application of oil-repellent superoleophobic surfaces. Polyzwitterionic brush surfaces are of particular interest, because of their ability to repel oil under water, even in the absence of micro-/nano-structures. The origin of this underwater superoleophobicity is attributed to the presence of a stable water film beneath the oil droplet, but this had not been demonstrated experimentally. Here, using optical interferometric techniques, we show that an oil droplet effectively hydroplanes over a water film, whose thickness is between one hundred and hundreds of nanometres. In addition, using a custom-built Droplet Force Apparatus, we measured the friction and adhesion forces to be in the nN range for millimetric-sized droplets. These forces are much lower than for other classes of well-known liquid-repellent surfaces, including the lotus-leaf effect and lubricant-infused surfaces, where the typical force is on the order of µN. arXiv:1906.09910v2 [cond-mat.soft]

Poly(butylene succinate) (PBS) is a biodegradable aliphatic polyester and is semicrystalline in nature. It has a wide range of engineering applications owing to its attractive combination of good processability and mechanical properties. PBS nanocomposites with graphene nanosheets were prepared by melt compounding. We report on their structure and their thermal, electrical, and mechanical properties. The thermal stability of the nanocomposite increased by 358C compared with that of neat PBS. The crystallization and melting behavior of the PBS matrix in the presence of dispersed graphene nanosheets were studied by differential scanning calorimetry and polarised optical microscope. We also observed an interesting phenomenon in the PBS/graphene nanocomposites from our FTIR investigation. b-form of PBS crystals are formed in the composite samples with 5 wt% graphene loading, which otherwise forms in pure PBS only under stress. We observed 12% modulus enhancement for 2 wt% PBS/graphene nanocomposites. The electrical conductivity increased to 10 5 -fold for 5 wt% PBS/graphene nanocomposites. POLYM. COMPOS., 38:E42-E48, 2017.

Surface wetting is a multiscale phenomenon where properties at the macroscale are determined by features at much smaller length scales, such as nanoscale surface topographies. Traditionally, the wetting of surfaces is quantified by the macroscopic contact angle that a liquid droplet makes, but this approach suffers from various limitations. In recent years, several techniques have been developed to address these shortcomings, ranging from direct measurements of pinning forces using cantilever-based force probes to atomic force microscopy methods. In this review, we will discuss how these new techniques allow for the probing of surface wetting properties in far greater detail. Advances in surface characterization techniques will improve our understanding of surface wetting and facilitate the design of functional surfaces and materials, including for antifogging and antifouling applications.