Preparation Of "Lotus Effect" Themo-cohesive Fiber Mats By Electrospinning

Owing to the evolution of hundreds of millions of years, the biological organisms in natural world had formed almost perfect structure and function to adapt to the complicated natural environment. Scientists had been committed to the research of specific structural and functional characteristics to get biomimetic materials. The study found that low surface energy materials and micro/nanometer composite surface structure are the two essential factors for the amazing “lotus effect”. Imitation of the Lotus effect through intricate facilities and techniques can get specific interface materials with superhydrophobic and self-cleaning properties, which play important role in the field of energy, environment, architecture and bio-engineering. Herein, a “lotus-effect” tape(LET) was designed to impart solid materials with superhydrophobicity using a technique as simple as taping. The so-called LET was prepared with a Janus structure using dual-nozzle electrospinning, and consisted of a lotus-effect mSiO2@PVDF upper layer and a thermo-cohesive PVDF/PVAc bottom layer. The LET can be pasted tightly onto the surface of various substrates via an ironing treatment with a household flatiron. The lotus-effect property was then endowed to the substrates. There were mainly two aspects we focused on:The first aspect is the preparation and the surface characteristics of the of the mSiO2@PVDF upper layer of the LET. The Janus composite mats were prepared by a series of mass ratio of doped mSiO2 nanoparticles in the PVDF solution. The surface morphology and composition of the as-prepared samples were characterized by the SEM and AFM. The results showed that as the introducing m SiO2 NPs into the PVDF fibers, the fibers became more and more rough as the amount of mSiO2 NPs(mass ratio) increased. The contact angles(CA) and the sliding angles(SA) were also measured to determine the surface wettability. As the increase of the mass ratio of mSiO2/PVDF the CA increased to as high as 175° and the SA decreased to less than 5°, excellent superhydrophobicity, which suggested that the Janus composite mats exhibits superhydrophobicity as excellent as the lotus leaf.The second aspect is preparation of the LET and the research of the modification behavior on the solid substrates. The LET with the mix spun PVDF/PVAc bottom layer was prepared and then heated through ironing. The bond strength of the Janus composite mats on the substrates was tested using a 90 peel strength testing machine. Moreover the detached behavior was also researched. THE LET covered glass slide was soaked in ethanol at room temperature for 30 s, and the LET can be detached easily and completely from the glass slide, without any damage. The recyclability of the detached LET was tested by repeating the process of ironing and alcohol exfoliation. We found that the LET can be reused 6 times at least to build up a lotus-effect surface on substrates.