Page 131 - Handbook of Surface Improvement and Modification

126 Easy Surface Cleaning and Stain Inhibition

Figure 8.6. Water contact angle on wool samples: (a) pristine wool; fabrics treated with (b) TiO 2 , (c) TiO 2 /SiO 2
70:30, (d) TiO 2 /SiO 2 50:50, and (e) TiO 2 /SiO 2 30:70. [Adapted, by permission, from Pakdel, E; Daoud, WA;
Wang, X, Appl. Surf. Sci., 275, 397-402, 2012.]
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showed excellent water repellency (contact angle above 150 on cotton and above 140 on
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polyester). The treated fabrics withstand 30 laundering cycles.
The photocatalytic self-cleaning fabrics are used for water-saving and environmen-
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tal-protection. In situ suspension polymerization was used to coat cotton fabric with
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nano TiO -acrylate copolymer for photocatalytic self-cleaning. A polymeric layer
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formed on the surface of nano TiO and hybrid was attached to the surface of fabric which
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had excellent self-cleaning properties.
The erosion-resistant self-cleaning coatings were obtained using hydroxyl-termi-
nated polydimethylsiloxane and tetraethylorthosilicate-based sol-gel network as a func-
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tional additive. The static water contact angle was 112°. The coating did not have
contact angle greater than 150° which will make it superhydrophobic but had excellent
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self-cleaning properties due to its good sliding properties.
Self-cleaning and superhydrophilic wool fabrics were functionalized using low-tem-
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perature sol-gel method with TiO /SiO nanocomposite. Titanium tetraisopropoxide and
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tetraethylorthosilicate were employed as precursors for TiO and SiO . The self-cleaning
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and hydrophilicity of wool fabrics were assessed based on the removal of coffee stain
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under UV and contact angle measurements. Fabrics functionalized with TiO /SiO 30:70
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showed the highest efficiency in stain removal (Figure 8.6). The presence of anatase
crystalline structure in synthesized nanoparticles was confirmed using the XRD patterns. 17
The presence of Ti−O−Si and Si−O−Si linkages was demonstrated using the FTIR pat-
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tern.
Polyvinylidenefluoride-based superhydrophobic coatings were used in self-cleaning
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applications. The coating was composed of PVDF as the matrix, N,N-dimethylforma-
mide as a solvent, aminopropyltriethoxysilane as the surface functionalizing agent and
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perfluorodecyltriethoxysilane as the hydrophobic modifier. Surface roughness was
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caused by addition of silica nanoparticles of 10-20 nm average particle size. The static