Sergiy Minko's Work Involves Nanostructured Responsive Materials
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applications include smart pores (membranes), responsive colloids
and capsules, micro valves and pumps, environment responsive lithography,
smart textiles, and hydrophilic/hydrophobic switches.
materials can be thin polymer films consisting of two different
incompatible polymers chemically grafted to the same solid substrate.
Such a layer is named a mixed polymer brush. The incompatible polymers
build segregated nanoscopic phases. The phase segregation mechanism
is strongly affected by the outside conditions (temperature, solvent,
pH). Properties of the materials coated with the layer can be strongly
alternated by applying external signals. For example, wetting behavior
can be switched from hydrophilic to ultrahydrophobic with a self
cleaning effect (Figure 1).
1. (a) Photograph of a water drop deposited onto the responsive
surface: the stroboscopic image shows that a water drop jumps and
rolls on the ultra-hydrophobic surface obtained after exposure of
the sample to toluene. (b) In contrast, exposure to acidic water
switches the sample to a hydrophilic state and the water drop spreads
on the substrate.
Strong morphological transformations of responsive materials can
be used for the fabrication of well ordered nanostructured functional
materials for nanoscale devices and system architectures compatible
with various operation environments and integrating across multiple
example, supermolecular block-copolymer assemblies can be used for
the fabrication of well ordered arrays of cylindrical nanodomains
or nanopores which can be filled with electro luminescence molecules,
metal clusters, or semiconducting particles (Figure 2). These materials
are very promising for light emitting devices, sensors, memories
providing the development of such challenging areas as nano-electronics,
nano-photonics, and nano-magnetics.
2. Morphological transitions in the block-copolymer film upon an
strategy to developing anisotropic materials with hierarchical architecture
across multiple length scales will be a revolutionary way to improve
products with special functional properties, which very often are
difficult to combine. For example, there is a strong need for polymeric
materials with a very high level of thermal and electrical conductivity
on the one hand, which, however, retain their visco-elastic properties
(e.g. sealing elastomers, glues, and printing plates) for electronics,
lithographic processes, constructing glues and other materials,
on the other hand. Different approaches, based on the application
of carbon, metal or metal oxide particles as well as short conductive
fibers, require a high proportion of the fillers/fibers in the material
to reach the percolation threshold when the inclusions form a continuous
(percolated) conductive net. Such approaches have frequently come
into a contradiction with desired mechanical properties of the composite
materials because of the high filling degree resulting in ridged
and brittle behavior of the composites.
desired percolation structures can be approached at a much lower
weight fraction (less than 5%) of the conductive fillers using an
appropriate size and shape of the conductive (nano)particles possessing
a high surface-to-volume ratio. Furthermore, if the conductive particles
are directed through a non-conductive matrix by a continuous minor
phase their content can be further reduced.
this end Professor Minko's approach is based on the application
of electro-spun nanofibers decorated with metallic nanoparticles
fabricated directly in situ on the fiber surface. The nanofibers
serve as carriers for the conductive particulates. In fact the fibers,
when introduced in a polymer matrix, form a cobweb-like continuous
net of the electro/thermoconductive nanoparticles.
more information about Professor Sergiy Minko and his research,
please call him at 315-268-3807 or send email to email@example.com.