(524d) A New Class of "Gecko Leg" Dendrimeric Polymeric Particles By Interfacial Templating of Multiphasic Liquids

Making mechanically stable coatings and bulk materials from polymer microparticles typically requires the use of a binding agent. An alternative strategy for glue-free adhesion and cohesion could be “contact splitting” which maximizes the contact area of an adherent to a substrate, as exemplified in gecko lizards’ nanofibrous setae. We will present a new class of nanofibrillated dendrimeric polymer particles (DPPs), which exhibit contact splitting effects on the microscale and are highly adhesive and cohesive due to their morphology. The DPPs are fabricated by an efficient and scalable process for liquid-based synthesis of nanomaterials by antisolvent precipitation in turbulently sheared medium. The process allows a variety of polymers to be readily shaped into nanofibrillated particles. The DPPs are hierarchically structured, with a big branched corona of nanofibers spreading out in all directions. The biomimetic similarity of their structure to the gecko lizards’ setae endows DPPs with excellent adhesion and cohesion properties. Our results demonstrate that this strong adhesion and cohesion can be attributed to the contact splitting phenomena and van der Waals interactions of their nanofibrous structures. This novel class of polymeric particles offers means to make strong non-covalent binding coatings and new types of dry adhesives. In addition, the DPPs exhibit high excluded volume, stemming from their hierarchical structure. They can build strong three-dimensional networks in numerous liquids, leading to gel-like behavior at concentrations as low as 1-2 vol.%. These particles have a broad range of potential applications and represent a system of fascinating phase behavior and structure building ability.