Mimicking the Wettability of the Rose Petal using Self-assembly of Waterborne Polymer Particles

In this work, we present a novel platform to synthesize polymeric “raspberry” particles and explore their use to fabricate surfaces with low wettability and high water adhesion, resembling the properties of naturally occurring surfaces such as the rose petal. The raspberry particles were obtained by layer-by-layer self-assembly of 850 nm core polystyrene particles bearing surface carboxylate groups and corona nanoparticles of different sizes and polymers (polystyrene, poly(para-fluorostyrene) or poly(2,3,4,5,6-penta-fluorostyrene), also bearing surface carboxylates), interleaved with positively charged poly(ally amine) hydrochloride. The raspberry particles were then bound together by covalent coupling of the carboxylate groups with the amine groups of the polymeric interlayer. The films produced by drop-casting the raspberry particles exhibited static water contact angles between ∼135° and ∼146°, depending on the nature of the corona, hysteresis of ∼135° and high adhesion of water droplets. Since all particles were synthesized from scratch by surfactant free emulsion polymerization in air and every step of the protocol was performed in water, this platform is up-scalable and environmentally friendly.