A dung beetle’s never too dirty. From Wikipedia.org
The biological concept of adaptation has sneaked into synthetic materials research. I was informed of this by a report on Adv. Mater.1 describing an adaptive non-adhesive surface. The report cited further for us a review on Prog. Polym. Sci.2 summing up the advances in fabricating smart surfaces by designing and synthesizing polymer brushes.
Yes. We have got encouraging advances in synthetic and fabricating skills, as evidenced by numerous reports on delicate yet strange structures on every issues of high impact chemistry journals, without, however, knowing the practical uses of them.
And ‘chemistry that really works’ cannot be easily achieved by conceiving such exciting concepts as ‘an adapting non-living thing’, ‘a smart nonintellectual being’, etc. In the particular case of non-adhesive surface, which we wish can be equally non-adhesive both in air and in water solutions, as the report on Adv. Mater. has excellently reviewed, even the smartest, most adaptive design by human failed. Adaptive surfaces for this purpose has been tried to achieved by grating amphiphilic polymers so that, the hydrophobic segments swell when placed in air, while the hydrophilic segments swell when place in aqueous solution, both cases being unfavorable for adhesion. However, the real products are not smart enough, they adapt too slow due to the slow motion of polymer chains. Softening the polymer surface make the surface sticky too due to increased contact area, which is favorable to adhesion.
When confronting such difficulties, we often turn to biomimetics too late. Soil animals which survive in varying humidity in soils have their solution to prevent soil adhesion on their skins, which are commonly a triple combination of cuticles with different smooth appearances, liquid secretion, and electrical charges. Although like in most cases, the structure-function relationship here is complex, we can well be satisfied by merely clumsy mimicking of its mechanism. Close-packed monodispersed silica nanpoarticles as the artistic ‘cuticles’ on dung beetles, or responsive stretching polymer chains as the ‘secretion’ behavior may be, perhaps, clumsy, but it seemed to work perfectly microscopically — the report1 only test the adhesiveness of the so-synthesized surface by atomic forced microscopy, that is at an atomic scale.
But we have a positive experience in the relation between atomic and macroscopic effects in terms of adhesive properties. The well known gecko foot mimic was also first tested by atomic forced microscopy in the Nature article by H. Lee et al.3, and lately demonstrated by Zhonglin Wang macroscopically4 with similar molecular design. I look forward to a macroscopic test for this non-adhesive counterpart.
1 
Roman Sheparovych, Mikhail Motornov, Sergiy Minko (2009). Low Adhesive Surfaces that Adapt to Changing Environments Advanced Materials DOI: 10.1002/adma.200802449
2 I LUZINOV, S MINKO, V TSUKRUK (2004). Adaptive and responsive surfaces through controlled reorganization of interfacial polymer layers Progress in Polymer Science, 29 (7), 635-698 DOI: 10.1016/j.progpolymsci.2004.03.001
3 Haeshin Lee, Bruce P. Lee, Phillip B. Messersmith (2007). A reversible wet/dry adhesive inspired by mussels and geckos Nature, 448 (7151), 338-341 DOI: 10.1038/nature05968
4 L. Qu, L. Dai, M. Stone, Z. Xia, Z. L. Wang (2008). Carbon Nanotube Arrays with Strong Shear Binding-On and Easy Normal Lifting-Off Science, 322 (5899), 238-242 DOI: 10.1126/science.1159503
