In nature, durable self-cleaning surfaces such as the Lotus leaf rely on the multiscale architect... more In nature, durable self-cleaning surfaces such as the Lotus leaf rely on the multiscale architecture and cohesive regenerative properties of organic tissue. Real-world impact of synthetic replicas has been limited by the poor mechanical and chemical stability of the ultrafine hierarchical textures required for attaining a highly dewetting superhydrophobic state. Here, we present the low-cost synthesis of large-scale ultradurable superhydrophobic coatings by rapid template-free micronano texturing of interpenetrated polymer networks (IPNs). A highly transparent texture of soft yielding marshmallow-like pillars with an ultralow surface energy is obtained by sequential spraying of a novel polyurethane-acrylic colloidal suspension and a superhydrophobic nanoparticle solution. The resulting coatings demonstrate outstanding antiabrasion resistance, maintaining superhydrophobic water contact angles and a pristine lotus effect with sliding angles of below 10° for up to 120 continuous abrasi...
It is proposed that two ideal amorphous structures, type I and type II, based on maximally random... more It is proposed that two ideal amorphous structures, type I and type II, based on maximally random jammed packing of spheres of equal size, form a distinct class of ideal amorphous solids. The ideal amorphous structures contain wide variations in local density, limited by the condition of solidity. Four distinct characteristics, based on statistical geometry and topology, are shown to define this class. Voronoi tessellations carried out on simulated cells of random packed spheres and amorphous polymers give a broad distribution of individual volumes, skewed, with a tail at the high volume end.
ABSTRACT The formation of the microdroplets on fibres for the MDT test offers an opportunity to c... more ABSTRACT The formation of the microdroplets on fibres for the MDT test offers an opportunity to carry out surface tension measurements based on the angle of contact between the resin and the fibre. Liquid microdroplets of epoxy were deposited on glass fibres, and their diameter, length and cone angle were measured. The equilibrium shape of the droplet can be derived from the principle of conservation of work and energy. If the surface tension of the polymer droplet and the specific surface energy of the polymer coated fibre are similar, then the interfacial tension is given simply by: γint = (1- m)γ , where m is the gradient of a linear plot of functions of the measured parameters and γ is the liquid surface tension. The measurement of contact angles on a droplet/fibre system have been reported previously; however, our method proposes a different geometry and consequently a simpler solution to the problem, with an additional advantage of verification on the droplet equilibrium and accuracy of measurements.
Metallurgical and Materials Transactions a Physical Metallurgy and Materials Science, 2011
The geometrical concept of an ideal solid and a method for its construction are presented as nove... more The geometrical concept of an ideal solid and a method for its construction are presented as novel contributions to the understanding of atomic arrangements in amorphous solids. This ideal amorphous structure serves as a base-line model for atomic arrangements and as a universal reference from which any changes in atomic arrangement can be measured. The model is intended to represent the ideal structure of amorphous solids and not the way a real glass is formed. This provides for amorphous materials the same kind of base-line reference as an ideal crystal does for real crystalline materials, or tiling patterns for quasi-crystalline materials. Characteristic properties are described, including Debye X-ray scattering to show how relevant information can be derived about the presence of vacancies and compositional changes.
In nature, durable self-cleaning surfaces such as the Lotus leaf rely on the multiscale architect... more In nature, durable self-cleaning surfaces such as the Lotus leaf rely on the multiscale architecture and cohesive regenerative properties of organic tissue. Real-world impact of synthetic replicas has been limited by the poor mechanical and chemical stability of the ultrafine hierarchical textures required for attaining a highly dewetting superhydrophobic state. Here, we present the low-cost synthesis of large-scale ultradurable superhydrophobic coatings by rapid template-free micronano texturing of interpenetrated polymer networks (IPNs). A highly transparent texture of soft yielding marshmallow-like pillars with an ultralow surface energy is obtained by sequential spraying of a novel polyurethane-acrylic colloidal suspension and a superhydrophobic nanoparticle solution. The resulting coatings demonstrate outstanding antiabrasion resistance, maintaining superhydrophobic water contact angles and a pristine lotus effect with sliding angles of below 10° for up to 120 continuous abrasi...
It is proposed that two ideal amorphous structures, type I and type II, based on maximally random... more It is proposed that two ideal amorphous structures, type I and type II, based on maximally random jammed packing of spheres of equal size, form a distinct class of ideal amorphous solids. The ideal amorphous structures contain wide variations in local density, limited by the condition of solidity. Four distinct characteristics, based on statistical geometry and topology, are shown to define this class. Voronoi tessellations carried out on simulated cells of random packed spheres and amorphous polymers give a broad distribution of individual volumes, skewed, with a tail at the high volume end.
ABSTRACT The formation of the microdroplets on fibres for the MDT test offers an opportunity to c... more ABSTRACT The formation of the microdroplets on fibres for the MDT test offers an opportunity to carry out surface tension measurements based on the angle of contact between the resin and the fibre. Liquid microdroplets of epoxy were deposited on glass fibres, and their diameter, length and cone angle were measured. The equilibrium shape of the droplet can be derived from the principle of conservation of work and energy. If the surface tension of the polymer droplet and the specific surface energy of the polymer coated fibre are similar, then the interfacial tension is given simply by: γint = (1- m)γ , where m is the gradient of a linear plot of functions of the measured parameters and γ is the liquid surface tension. The measurement of contact angles on a droplet/fibre system have been reported previously; however, our method proposes a different geometry and consequently a simpler solution to the problem, with an additional advantage of verification on the droplet equilibrium and accuracy of measurements.
Metallurgical and Materials Transactions a Physical Metallurgy and Materials Science, 2011
The geometrical concept of an ideal solid and a method for its construction are presented as nove... more The geometrical concept of an ideal solid and a method for its construction are presented as novel contributions to the understanding of atomic arrangements in amorphous solids. This ideal amorphous structure serves as a base-line model for atomic arrangements and as a universal reference from which any changes in atomic arrangement can be measured. The model is intended to represent the ideal structure of amorphous solids and not the way a real glass is formed. This provides for amorphous materials the same kind of base-line reference as an ideal crystal does for real crystalline materials, or tiling patterns for quasi-crystalline materials. Characteristic properties are described, including Debye X-ray scattering to show how relevant information can be derived about the presence of vacancies and compositional changes.
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