The Study of Wetting Properties on Broccoli Leaf Surfaces and their Time Dependent Self-Healing After Mechanical Damage

David Wang Auditorium, 3rd floor Dalia Maydan Bldg.
Beni Rich, MSc candidate

Beni Rich, MSc candidate
Department of Material Science and Engineering, Technion
Most plants demonstrate complex surfaces called cuticles to protect themselves from the environment. The cuticle acts as a boundary between the plant and its environment and covers the majority of the plants organs. It is predominantly a lipid material which is composed of an insoluble cutin frame work in which soluble long-chain waxes are dispersed. These waxes accumulate on the cutical surface and via self-assembly can create three dimensional epicuticular crystals. The microstructure of the plant cuticle is extremely diverse. Different species of plants have different cell formations, different surface folds, and varying microstructure of their epicuticular wax crystals. Since there are many different wax compositions the epicuticular wax crystals present different morphologies which can contribute to the variation in properties of the surfaces.
The cuticle has many functions, foremost of which is to serve as a transport barrier and reduce water loss. The cuticle also reduces or increases surface wettability and serves to give the plant anti-adhesive, anti-biofouling, and self-cleaning properties. Finally it can also provide protection from harmful radiation and reduction of surface temperature.
Bioinspired research deals for the most part with translating biological strategies to practical engineering solutions for day to day problems. Prominent examples of bioinspired applications in relation to plant surfaces can be seen in the development of superhydrophobic surfaces based on the Lotus phenomenon. The potential application of super-hydrophobic surfaces in the industry is great and so there is great motivation to study biological systems with interesting wetting properties.
The objective of this research was to study the wetting properties of the Brassica oleracea var. italic (i.e. common broccoli) surface and evaluate its recovery after mechanical damage. In particular interest was the recovery of wetting related properties and the behavior of biofilms on the plant surface. This is relevant as at the moment the use of self-cleaning surfaces is limited by the fact that the micro- and nano-scale structures in said surface are very susceptible to wear and so must be constantly maintained. Furthermore we strove to understand the physical properties of the broccoli wax; from the surface energy of the rough wax surface to the thermal behavior of the wax. The results of our study will be presented in the upcoming seminar.
MSc Advisor: Prof. Boaz Pokroy