This work reported the dynamic effects of water droplet impact on flat, porous and pincushion structure films of star shaped polyhedral oligomeric silsesquioxane (POSS) fluorinated acrylates, POSS-poly(trifluoroethyl methacrylate) (POSS-(PTFEMA)) and POSS-(poly(trifluoroethyl methacrylate)-b-poly(methyl methacrylate)) (POSS-(PTFEMA-b-PMMA)), using the breath figure method. The porous and pincushion structure films with different surface chemical compositions were obtained by controlling the copolymer structure and temperature and by stripping of the surface. The water contact angles on the different films were measured, and the water droplets on the pincushion structure films when reversed at 45°, 90°, 135° and 180° were also studied. It was found that the pincushion structure films revealed a water adhesion ability. Furthermore, the water droplet impact behavior on these films was investigated. The morphology variations of water droplets, spreading diameter of the droplets, energy conversion, restitution coefficient and adhesion force were examined. Finally, the schematic illustration of water droplets under the static and dynamic states in contact with the pincushion and porous structure surfaces was proposed. It is critical to materialize various applications such as microdroplet transportation, soil erosion, spray painting, anti-icing surface and antifouling agents for textiles.
This
work reported the static and dynamic hydrophobic properties
of the honeycomb porous and peeled films with pincushion structures
by changing the concentrations of the copolymer solution. Honeycomb
porous films were fabricated via breath figure technology employing
a pentablock copolymer containing poly(ethylene glycol)/PEG, poly(methyl
methacrylate)/PMMA, and poly(trifluoroethyl methacrylate)/PTFEMA.
The relationship between the copolymer concentrations and the pore
size (D) and rim width (W) was examined.
Moreover, we studied the hydrophobic properties from different surfaces
of flat, porous, and pincushion structures, and the contact angles, W/D ratios, and fraction of air on the
porous and pincushion films were obtained. It was noteworthy that
the W/D ratios and surface hydrophobic
properties had a notable correlation. Finally, the dynamic behaviors
of water droplets impacting on these porous and pincushion films were
examined using a high speed camera. It examined the influence of the
fraction of air on the measurement of the dynamic morphologies, contact
angle in equilibrium state, maximum spreading diameter and maximum
height of the droplet, and adhesive property of porous and pincushion
films. The films obtained in this paper may have some potential applications
as hydrophobic, self-cleaning, and antibacterial surfaces.
Electrospinning provides a versatile, efficient and low-cost method for the preparation of continuous nanofibres from various polymers. In this study, the polyhedral oligomeric silsesquioxanes (POSS) block copolymer was synthesized via atom transfer radical polymerization. The smooth fiber, porous fiber or hierarchically porous microspheres were prepared by electrospinning from POSS block copolymer, poly(vinylidene fluoride) (PVDF) and aluminium oxide (Al 2 O 3 ). The influence of copolymer concentration, the ratio of the solvents, the diameter and concentration of the Al 2 O 3 on the surface morphology were investigated. Porous fibers and porous microspheres were prepared by regulating the ratio of the solvents from the phase separation and breath figure methods. The dynamic behavior of the water droplet with the constant volume impacting on the electrospinning films were reported. The morphology evolution, restitution coefficient, the change of energy of the water droplets are examined. The droplet bounces several times on the superhydrophobic surface, while the droplet remains pinned and does not rebound when the contact angles was lower than 150°. On the other hand, the water droplets were splashed on the Al 2 O 3 based electrospinning films. Finally, the mechanical properties of the electrospinning films were investigated.
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