Structural and Functional Properties of Fluorinated Silica Hybrid Barrier Layers on Flexible Polymeric Foil

Abstract

The reported work was focused on sol–gel-derived organically modified and fluorinated silica coatings deposited on elastic polymeric foil. The structure and topography of the coatings were tested by infrared spectroscopy and microscopic studies. The functional properties were determined using thermal analysis, surface analysis, and oxygen permeability tests. The barrier feature of the investigated materials against oxygen was correlated with the properties of the coatings. The hybrid (organic–inorganic) structure of the coatings was proven, demonstrating the presence of a silica network modified with alkyl and fluoroalkyl groups since precursors with the isooctyl group or different lengths of the fluoroalkyl chains were used for the syntheses. The coatings were free of defects and had a smooth surface except for the sample containing the longest fluoroalkyl chain (perfluorododecyl group), which showed a wrinkle-like surface. The hydrophobic character of the coatings increased, whereas the oxygen permeation coefficient values decreased (reaching a fourfold lower coefficient in comparison to the bare substrate) with a higher content of the fluorinated carbon atoms in the structure. The results were enriched by the information from the thermomechanical analysis as well as nanoindentation and scratch tests giving values of the glass transition temperature, thermal expansion coefficient, coatings adhesion, and hardness of the investigated systems.

A Novel Strategy for Creating an Antibacterial Surface Using a Highly Efficient Electrospray-Based Method for Silica Deposition

“…This phenomenon is caused by the increased roughness on a hydrophobic surface that enhances air entrapment within the micro- or nano-structures, resulting in a lower penetration ability and free movement of the liquids; thus, the bacteria can be easily removed and detached from the surface [ 31 ]. Another similar study by Startek et al [ 32 ] reported that the deposition of SiO 2 with ten fluorinated carbons in the alkyl chain (-CF 10 ) using spin-coating method onto PET substrate exhibits R RMS and R a values of 63.1 and 78.3 nm, respectively and increases the WCA value to 113°. In order to achieve superhydrophobicity, an increase of surface roughness is needed to reach a higher R RMS value, as reported by Ozkan et al [ 33 ], who successfully fabricated a Cu-nanoparticles-coated polydimethylsiloxane (PDMS) substrate with WCA = 151° and R RMS = 230 nm.…”

“…As deposition of coating materials has been reported to affect surface topography [ 31 , 32 , 33 , 34 ], we performed AFM to analyze the roughness of our fabricated surface. As shown in Figure 2 G, on one hand, the deposition of SiO 2 onto PET substrate showed root-mean-square roughness ( R RMS ) and average roughness ( R a ) values of 82.50 ± 16.22 nm and 65.15 ± 15.26 nm, respectively.…”

“…Furthermore, the association between surface topography and bacterial adhesion has also been reported as several studies have shown a reduction of bacterial growth when surface roughness is increased on the surface [ 31 , 32 , 33 , 34 ]. Similarly, our current study demonstrated that the deposition of SiO 2 onto PET substrate increases the surface roughness ( R RMS value of 82.50° ± 16.22° nm and R a value of 65.15 ± 15.26 nm, respectively), resulting in an increase in the WCA value to more than 90°, and both increased surface roughness and increased hydrophobicity of synergistically SiO 2 -PET substrate could reduce the bacterial adhesion on the surface ( Figure 2 E–G, Figure 4 B–D and Figure 5 B–D).…”

Multiscale Textured Mesh Substrates that Glide Alcohol Droplets and Impede Ice Nucleation

“…The characteristic absorption bands of the −CF 2 and −CF 3 groups can be distinguished in the 1120–1250 cm −1 region. [ 1,54–57 ] Stretching bands at 1231 and 1198 cm −1 are assigned to asymmetric ((−CF 2 ) and (−CF 3 )) stretching modes, whereas bands at 1144 and 1134 cm −1 correspond to symmetric ((−CF 2 )) stretching modes. [ 1,52,58 ] Characteristic Si–O–Si asymmetric stretching (((OSi 2 )) modes are observed at 1113, 1063, and 1015 cm −1 , whereas a symmetric stretching (((OSi 2 )) band is noted at 804 cm −1 .…”

Sol-Gel Coatings with Azofoska Fertilizer Deposited onto Pea Seeds

“…The silica coatings pure and doped with different substance (fertilizer) could be easily produced by the sol-gel method. It is known that silica coatings show good adhesion to various materials (metallic substrate [ 37 ], textile fabrics [ 38 ], polymers [ 39 ], and others [ 40 ]), thereby the idea to apply them on seeds emerged. Reagents used in a sol-gel synthesis (silica precursor and water) as well as ethanol as a by-product, are not harmful to seeds, but the idea of using sol-gel coatings for seeds modifications is poorly presented in the literature.…”