Bulk Materials that are Inherently Liquid Repellent

1 Bulk Materials that are Inherently Liquid Repellent 

2 Materials that become Liquid Repellent with Mechanical Wear 

During the last years, the amount of published material regarding the development of mechanically durable liquid repellent surfaces has exponentially increased. Various techniques have been demonstrated that can 

Currently, however, quantitative assessment of the mechanical durability of non-wetting surfaces is difficult due to the diversity of wear testing and characterization methods discussed above. Ideally, the evaluation techniques should be more standardized and possibly reduced in number, as this would be beneficial for focused efforts to develop resilient coatings. From all the techniques that we described above, there seem to be some of them that are more commonly accepted. Linear abrasion, for instance, seems to be a very well accepted and is a common method to evaluate the mechanical durability. Sand, water/jet and gas impact are also good techniques to evaluate the stability of the surfaces for outdoor applications. Nevertheless, the range of possible applications for super hydrophobic surfaces may call for specialized mechanical tests like laundry tests, finger touch, etc. 

Finally, apart from the standardized test methods that should be used, it is of extreme importance for reasons of consistency that researchers measure both static and dynamic contact angles in their experiments, otherwise it is impossible to compare the performance of a surface to studies published by other researchers. Selecting also standardized physical quantities and materials in the tests would also be beneficial (e.g. applied pressure and abradant materials). 

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