Fabrication of Superhydrophobic Textiles
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hydrophobicity to the textile but, there is issue with their application that they release
formaldehyde and cause loss of mechanical strength such as decrease of tear strength,
abrasion resistance along with change in shade percent of dyed fabrics. Due to the
health hazards or carcinogenic nature of released of formaldehyde their application is
limited now [24, 29]. The minimum concentration of about 0.1 ppm [30]. Stearic acidmelamine could be used at spacious and airy workplaces to be effectively applied on
textiles by exhaustion or most commonly padding to make it hydrophobic. But still
by proper monitoring and taking precautionary measures during application worker’s
health could be saved. Some time they are used in combination with other repellents
like fluorochemicals in order to reduce the consumption of these chemicals and to
improve the overall performance of textile.
Silicone Water Repellents
The superb water repellency could be achieved by treating textiles with hydrophobic silicone compositions. On silicon molecules long chain hydrocarbon serve the
function of hydrophobicity and the silicon could enter the surface of textile the
hydrophobic groups could be delivered deeply inside or through the substrate. Also
the edge of stability of the silicon make them the best choice though to make textile
durable hydrophobic but breathable with soft hand feel. Silicons or siloxanes and
fluorocarbon based repelling agents are the most widely used. Silanes have –O–Si–
O– backbones and the attached alkyl groups (can be with different chain lengths)
mainly provide water repellency. They are responsible to lower the surface energy
of textile to about 20 dyne/cm imparting hydrophobic nature to substrate.
The polydimethylsiloxanes are mostly used to provide the hydrophobic layer at
the fabric surface as they form chemical bonding (usually hydrogen bonding) with
the cellulose even at low concentration about 0.5–1% o.w.f. they could serve the
purpose of hydrophobicity. The reaction of siloxanes with cellulosic textile require
temperature of 120–250 °C for complete attachment with the textile and time required
could be from several minutes to several hours to obtain satisfactory hydrophobicity.
Fluorocarbon-Based Repellents
Fluorocarbon based repellents are mostly copolymers that are mainly synthesized
by perfluoroalkyl groups incorporated into urethane or acrylic monomers. The perfluoroalkyl groups were originally synthesized by electrochemical fluorination but,
now a days they have been prepared by telomerisation. These monomers are then
polymerized to from hydrophobic finishes. These repelling agents are providing the
fibers with lowest surface free energy, thus, making fabric oil, water and soil repellent. Fluorine containing esters when come in contact with the fibers they arrange
themselves vertically on textile surface, lowering the surface energy depending upon
the distribution and orientation of perfluoroalkyl groups. The finish when applied
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hydrophobicity to the textile but, there is issue with their application that they release
formaldehyde and cause loss of mechanical strength such as decrease of tear strength,
abrasion resistance along with change in shade percent of dyed fabrics. Due to the
health hazards or carcinogenic nature of released of formaldehyde their application is
limited now [24, 29]. The minimum concentration of about 0.1 ppm [30]. Stearic acidmelamine could be used at spacious and airy workplaces to be effectively applied on
textiles by exhaustion or most commonly padding to make it hydrophobic. But still
by proper monitoring and taking precautionary measures during application worker’s
health could be saved. Some time they are used in combination with other repellents
like fluorochemicals in order to reduce the consumption of these chemicals and to
improve the overall performance of textile.
Silicone Water Repellents
The superb water repellency could be achieved by treating textiles with hydrophobic silicone compositions. On silicon molecules long chain hydrocarbon serve the
function of hydrophobicity and the silicon could enter the surface of textile the
hydrophobic groups could be delivered deeply inside or through the substrate. Also
the edge of stability of the silicon make them the best choice though to make textile
durable hydrophobic but breathable with soft hand feel. Silicons or siloxanes and
fluorocarbon based repelling agents are the most widely used. Silanes have –O–Si–
O– backbones and the attached alkyl groups (can be with different chain lengths)
mainly provide water repellency. They are responsible to lower the surface energy
of textile to about 20 dyne/cm imparting hydrophobic nature to substrate.
The polydimethylsiloxanes are mostly used to provide the hydrophobic layer at
the fabric surface as they form chemical bonding (usually hydrogen bonding) with
the cellulose even at low concentration about 0.5–1% o.w.f. they could serve the
purpose of hydrophobicity. The reaction of siloxanes with cellulosic textile require
temperature of 120–250 °C for complete attachment with the textile and time required
could be from several minutes to several hours to obtain satisfactory hydrophobicity.
Fluorocarbon-Based Repellents
Fluorocarbon based repellents are mostly copolymers that are mainly synthesized
by perfluoroalkyl groups incorporated into urethane or acrylic monomers. The perfluoroalkyl groups were originally synthesized by electrochemical fluorination but,
now a days they have been prepared by telomerisation. These monomers are then
polymerized to from hydrophobic finishes. These repelling agents are providing the
fibers with lowest surface free energy, thus, making fabric oil, water and soil repellent. Fluorine containing esters when come in contact with the fibers they arrange
themselves vertically on textile surface, lowering the surface energy depending upon
the distribution and orientation of perfluoroalkyl groups. The finish when applied