The
integration of nanometer-sized fillers into polymer matrices
to create nanocomposite materials has attracted a great deal of interest,
not only because these materials can be tailored to specific practical
applications but also because they can exhibit synergistic combinations
of properties that display multifunctionality. Herein, we successfully
incorporated silica (SiO2) nanoparticles into the rubber-modified
polybenzoxazine (PBZ) by mixing and applied as a nanocomposite coating
that exhibits both superhydrophobicity and superoleophilicity through
a facile dipping and spraying technique. We used PBZ, not only because
of its near-zero shrinkage upon polymerization, chemical resistance,
and good dielectric, thermal, and mechanical properties but also because,
most importantly, of its low surface free energy and low water absorptivity.
With superhydrophobicity coexisting with superoleophilicity in one
material, potential anticorrosion, anti-ice, and organics/water separation
applications of the coating were investigated. Results revealed that
the rubber-modified PBZ coating with the optimum SiO2 loading
was able to display superior antiwettability and anticorrosion performance
even during prolonged exposure to corrosive environment. The coating
also showed promising anti-icing ability by preventing ice/snow from
adhering to the surface and delaying icing of water upon striking
the surface. Furthermore, when our coating was applied onto a metal
mesh, the resulting coated membrane was able to effectively separate
dichloromethane (DCM), a nonpolar oil, from water. Combined with good
thermal and adhesion properties, the existence of all the aforementioned
properties makes the developed nanocomposite a very promising coating
material for multifunctional application purposes.
A simple and robust alternative for fabricating stimuli-responsive 2D self-folding films was introduced. The approach combines metal-sputtering, layer-by-layer assembly of polyelectrolytes, and transfer-printing of the bilayer film onto a substrate coated with a sacrificial layer. With this technique, self-folding bilayer films can be fabricated without using harsh chemical etchants, complicated chemical synthesis, or complex lithographic techniques. Upon release, the microsized 2D film is shown to reconfigure into a 3D structure caused by a mismatch in the properties of the individual layers. The actuation of the bilayer film can be triggered by partial swelling due to absorption of water or by partial expansion of one of the layers due to an increase in temperature.
Membrane cleaning & disinfection is a bottleneck in the filtration processes of the food industry. Disinfection by oxidative agents, such as NaOCl, have been clearly identified as the main responsible of the accelerated ageing of polymer membranes. The development of new formulated biocide detergents allowing to respect the integrity of polymer membranes is our objective. A major difficulty to overcome is to have a method making it possible to rapidly demonstrate whether the membrane will age after a long-time contact with the biocide in industrial conditions of use. However, nowadays the estimation of membrane ageing is mainly achieved by long-time consuming methods, limiting biocide & detergent developments. This paper proposes an original approach allowing a time-efficient discrimination of biocide detergent prototypes with respect to the membrane long-term ageing. The methodology is firstly based on the use of microwaves activation to accelerate the membrane degradation (if any) in the biocide solution set at a concentration selected to avoid too severe degradations never reached at industrial scale. Secondly, the combination of MW results and short time filtration gives rapidly relevant information about the suitability (or not) of a tested prototype with respect to the membrane flux behaviour. ATR-FTIR characterisation is shown to be relevant as the single analytical tool to follow the entire approach. Finally, only the promising prototype enter in long-term filtration validation tests, with a real opportunity to avoid unnecessary experiments. For the sake of the demonstration, the methodology is applied aiming at the formulation of a non-oxidative formulated biocide detergent that can be used either for RO or UF. The results evidence a non-intuitive conclusion: the new biocide validated for RO polyamide membrane (fragile toward NaOCl biocide oxidant and hydrophilic) has to be avoided for the more chemically resistant but also more hydrophobic UF PES/PVP membrane.
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