Page 148 - Handbook of Surface Improvement and Modification

9.1 Methods and mechanisms of hydrophobization 143

Figure 9.7. Self-hydrophobization. [Adapted, by permission, from Redzheb, M; Van Der Voort, P; Armini, S,
Microporous Mesoporous Mater., in press, 2018.]

cles as observed from the absence of micropores in the polyhexylsilsesquioxane coating
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layer. The hydrodynamic diameter of the surface-hydrophobized magnetite nanoparti-
cles was 143 nm, which was 10 times larger than the original grain size of the magnetite
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nanoparticles.
Template-dependent hydrophobicity in mesoporous organosilica films has been
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reported (Figure 9.7). The film with the smallest pore size of 1.7 nm, templated by cetyl-
trimethylamino chloride, results in higher hydrophilicity when compared to films with a
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pore size of 4.1 or 5.3 nm. The self-hydrophobization process depends on a steric hin-
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drance.
The hierarchical structure of wood is composed of a cellulose skeleton of high struc-
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tural order. Functionalization of wood at the level of cell and cell walls contributes to
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new properties on a level of large-scale engineering materials applications. By using
methacryl groups inserted into wood cell walls as the anchor points for grafting, various
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polymers can be inserted into the wood structure. Polystyrene grafted in the case of
methacryloyl chloride contribute to location of polymer at the interface between the cell
lumina and the cell wall covering the inner surface of the cells and being traceable up to 2-
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3 μm in the cell wall. In the case of methacrylic anhydride, the polymer was located
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inside the whole cell wall.
A fluorine-free polymeric water-repellent agent was used for creation of superhydro-
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phobic fabrics. A polymeric alkylsilane, poly(isobutyl methacrylate-co-3-methacryloxy-
propyltrimethoxysilane) was synthesized to replace the commercial long-chain
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perfluoroalkylsilane water-repellent agent. The superhydrophobic polyester fabrics were