| Abstract |
In recent years the development of hydrophobic and especially superhydrophobic
surfaces has attracted considerable attention thanks to their numeral potential
applications. One of their most interesting applications, is the development of selfcleaning and anti-fouling surfaces, which can find use in building materials and
cultural heritage monuments for their outdoor protection, as well as in textiles for the
development of self-cleaning products. The combination of low surface energy and
hierarchical roughness can lead to a contact angle over 150°. Whereas when
superhydrophobicity is combined with a small contact angle hysteresis, a surface can
develop anti-dust properties and is considered to be self-cleaning. Further than
hydrophobicity, these surfaces can exhibit oleophobicity in many organic solvents, as
well.
In the current work, we have studied the surface properties of flexible polymer
films, on which a nanocomposite coating (polymer/inorganic) was deposited. In
particular, Low Density Polyethylene (LDPE) polymer films were utilized, the surface
of which had been modified by Corona Treatment, while the coating consisted of a
low surface energy polymer (Silres BS 4004) and hydrophilic inorganic Silicon
dioxide (SiO2) nanoparticles. Nanoparticles of three different sizes were utilized;
more specifically their diameters were 14nm, 37nm, and 134nm. Initially, the LDPE
films were coated with pure Silres BS 4004 using solutions of different concentration,
so as to study its effect on the surface properties of the coated films. The
concentration of the polymer that was found to have the optimum surface properties
was used for the development of the nanocomposite coatings that contained SiO2
nanoparticles as well. In the latter case, the effect of the nanoparticle size as well as of
their concentration on the surface properties of the coated polymer films was
examined. The surface properties were evaluated via Contact Angle measurements,
during which a water droplet was deposited on the surface of the coated films, to
study their hydrophobicity, whereas various organic solvents like Glycerol, Ethylene
Glycol and DMSO were utilized to examine their oleophobic behavior as well.
Scanning Electron Microscopy was used to study the surface topography as well as
the surface roughness to provide complementary information towards understanding
our results. The raw materials (LDPE, Silres BS 4004) as well as the coatings that
exhibited the optimum results were characterized, using Differential Scanning
Calorimetry (DSC), Thermogravimetric Analysis (TGA) and UV-Vis spectrometry, in
order to compare the initial thermal and optical properties of the LDPE film with
those of the coated films.
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