Fabrication of Superhydrophobic Textiles
207
the textile modification by use of TiO 2 nanoparticles is a two-step process in which
TiO 2 nanoparticles have been coated on cotton micrometer-scale fibers to create the
nanoroughness and after this modification in next step post-treatment with some
repellent like dodecafluoroheptyl-propyl-trimethoxysilane is done to develop excellent water repellent textiles with a WCA of 160° [52] along with other properties
such as UV protection and dye degradation. Inspired by the hierarchical alignment
of lotus leaf, different morphological structures of TiO 2 have also been applied onto
textile to investigate the structural effect on its properties. In this regard a study
was done by Huang et al. [53] in which marry-gold like TiO 2 nano-flowers were
synthesized and deposited uniformly on cotton fabric by hydrothermal process, via
facile strategy. Then the treated cotton fabric was coated with mixed methanolic
solution of 1H,1H,2H,2H-per-flourodecyltriethoxysilane (F17) to prepare a robust
superhydrophobic fabric with a water contact more than 160° and sliding angle less
than 10°. Furthermore, the modified fabric demonstrated outstanding UV shielding,
self-cleaning and water-oil separation.
Though the photocatalysts have been applied for multifunctional properties on
textiles, but, the effect of these functional materials on the properties of textile is
controversial. They generate highly reactive species know as reactive oxygen species
(ROS; OH
• , O
•−2 ) by absorbing electromagnetic radiation in UV region and these
ROS are responsible for organic decay. As cellulose is also organic thus these ROS
could also have detrimental effect on their contact with the cellulosic fibers [51,
54]. Thus the mechanical properties such as tear strength, tensile strength, abrasion
resistance could be lost when the cellulosic textile is treated with photocatalysts like
TiO 2 and ZnO etc. due to crystalline changes of cellulosic structure [55].
Due to the negative effects on dyed fabrics and the loss in mechanical properties mostly the SiO 2 nanoparticles have been used for manufacturing of superhydrophobic textile due to inert nature of SiO 2 nanoparticles. A researcher St ¨
ober
developed the Sol-gel process for nanoparticle’s synthesis that has been used now
by many researchers to generate nanoroughness at the substrate with few modifications. TEOS: tetraethyl orthosilicate and some organic solvents or distilled water are
the most commonly used precursors for fabrication of SiO 2 nanoparticles by solgel process. After synthesis these nanoparticles have been applied by conventional
pad-dry-cure method onto textile for surface morphological change by creation of
nanoroughness. Then post treatment by repellents made textile hydrophobic with
water contact angle of greater than 130° [56]. In early experimentation, the water
contact angle was lower than 150° mostly and the textiles were not superhydrophobic. Therefore the rigorous researches were carried on to mimic the lotus leaf and
to attain the angle more than 150°. Several chemicals were tried and it was known
after intensive research that fluoroalkylsiloxane could be best repellents providing
superhydrophobic nature to textiles. Thus Hao et al. [57] reported application of SiO 2
nanoparticles for nanoroughness and treatment with fluoroalkylsiloxane that lowered
the surface energy enough to increase WCA 138°–156.5°. Thus, an approach was
adopted that was near to lotus leaf effect.
The extent of hydrophobicity could be dependent upon the chain length of
repellent silane coupling agents. To confirm this and to find the best hydrophobe
207
the textile modification by use of TiO 2 nanoparticles is a two-step process in which
TiO 2 nanoparticles have been coated on cotton micrometer-scale fibers to create the
nanoroughness and after this modification in next step post-treatment with some
repellent like dodecafluoroheptyl-propyl-trimethoxysilane is done to develop excellent water repellent textiles with a WCA of 160° [52] along with other properties
such as UV protection and dye degradation. Inspired by the hierarchical alignment
of lotus leaf, different morphological structures of TiO 2 have also been applied onto
textile to investigate the structural effect on its properties. In this regard a study
was done by Huang et al. [53] in which marry-gold like TiO 2 nano-flowers were
synthesized and deposited uniformly on cotton fabric by hydrothermal process, via
facile strategy. Then the treated cotton fabric was coated with mixed methanolic
solution of 1H,1H,2H,2H-per-flourodecyltriethoxysilane (F17) to prepare a robust
superhydrophobic fabric with a water contact more than 160° and sliding angle less
than 10°. Furthermore, the modified fabric demonstrated outstanding UV shielding,
self-cleaning and water-oil separation.
Though the photocatalysts have been applied for multifunctional properties on
textiles, but, the effect of these functional materials on the properties of textile is
controversial. They generate highly reactive species know as reactive oxygen species
(ROS; OH
• , O
•−2 ) by absorbing electromagnetic radiation in UV region and these
ROS are responsible for organic decay. As cellulose is also organic thus these ROS
could also have detrimental effect on their contact with the cellulosic fibers [51,
54]. Thus the mechanical properties such as tear strength, tensile strength, abrasion
resistance could be lost when the cellulosic textile is treated with photocatalysts like
TiO 2 and ZnO etc. due to crystalline changes of cellulosic structure [55].
Due to the negative effects on dyed fabrics and the loss in mechanical properties mostly the SiO 2 nanoparticles have been used for manufacturing of superhydrophobic textile due to inert nature of SiO 2 nanoparticles. A researcher St ¨
ober
developed the Sol-gel process for nanoparticle’s synthesis that has been used now
by many researchers to generate nanoroughness at the substrate with few modifications. TEOS: tetraethyl orthosilicate and some organic solvents or distilled water are
the most commonly used precursors for fabrication of SiO 2 nanoparticles by solgel process. After synthesis these nanoparticles have been applied by conventional
pad-dry-cure method onto textile for surface morphological change by creation of
nanoroughness. Then post treatment by repellents made textile hydrophobic with
water contact angle of greater than 130° [56]. In early experimentation, the water
contact angle was lower than 150° mostly and the textiles were not superhydrophobic. Therefore the rigorous researches were carried on to mimic the lotus leaf and
to attain the angle more than 150°. Several chemicals were tried and it was known
after intensive research that fluoroalkylsiloxane could be best repellents providing
superhydrophobic nature to textiles. Thus Hao et al. [57] reported application of SiO 2
nanoparticles for nanoroughness and treatment with fluoroalkylsiloxane that lowered
the surface energy enough to increase WCA 138°–156.5°. Thus, an approach was
adopted that was near to lotus leaf effect.
The extent of hydrophobicity could be dependent upon the chain length of
repellent silane coupling agents. To confirm this and to find the best hydrophobe