Soft dendritic microparticles with unusual adhesion and structuring properties

The interplay between morphology, excluded volume and adhesivity of particles critically determines the physical properties of numerous soft materials and coatings^1-6. Branched particles² or nanofibres³, nanofibrillated cellulose⁴ or fumed silica⁵ can enhance the structure-building abilities of colloids, whose adhesion may also be increased by capillarity or binding agents⁶. Nonetheless, alternative mechanisms of strong adhesion found in nature involve fibrillar mats with numerous subcontacts (contact splitting)^7-11 as seen in the feet of gecko lizards and spider webs^12-17. Here, we describe the fabrication of hierarchically structured polymeric microparticles having branched nanofibre coronas with a dendritic morphology. Polymer precipitation in highly turbulent flow results in microparticles with fractal branching and nanofibrillar contact splitting that exhibit gelation at very low volume fractions, strong interparticle adhesion and binding into coatings and non-woven sheets. These soft dendritic particles also have potential advantages for food, personal care or pharmaceutical product formulations.