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M. Ashraf and S. Riaz
a research was done in which silanes with different chain lengths were used
to lower the surface energy along with silica nanoparticles. Cross linker was
added to enhance the durability of nanoparticles. From the study it was confirmed that n-dodecyltrimethoxysilane was the best hydrophobe due to longest
chain length among seven repelling agents such as n-octadecyltrimethoxysilane,
n-dodecyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-butyltrimethoxysilane,
n-ethyltrimethoxysilane, n-octyltrimethoxysilane, and methyltrimethoxysilane [44].
As the nanoparticle do not have the affinity for textiles, therefore, some binders
have been used [58–60] to increase their adhesion with the substrate mentioned
previously in this chapter. Due to the application of binders the comfort and properties like tear strength have been compromised [61]. Therefore, there was a need
to find a way out to improve the durability without affecting the inherent characteristics of the textile. The researchers tried to functionalize the nanoparticles
with silane coupling agents to directly bind them with the textile without using any
crosslinker. Riaz et al. [1] investigated the comfort properties by developing highly
durable superhydrophobic textiles by application of 3-(Trimethoxysilyl) propylN,N,N-dimethyloctadecyl ammonium chloride and 3-Glycidoxypropyl)trimethoxysilane modified SiO 2 nanoparticle at cotton fabric. It was found that water contact
angle of nearly 150° was obtained without compromising the comfort properties and
functionality up to 20 industrial washing cycles was obtained.
To make the surface very near to lotus effect binary hierarchical roughness in more
than one layer was also tried to be created at the textile to attain maximum WCA.
In this regard, different sizes of SiO 2 nanoparticles were used with two silanes.
First layer of 3-aminopropyl triethoxysilane functionalized SiO 2 nanoparticles was
applied onto textile and then 2nd layer of 3-glycidoxypropyltrimethoxysilane functionalized SiO 2 nanoparticles was deposited onto the 1st layer. The deposition of
different sized nanoparticles created the binary hierarchical roughness at the substrate. Due to direct relationship between surface morphology, surface roughness
and water contact angle it was possible to tailor the water contact angle [62]. Xue
et al. [63] also presented same type of study in which binary roughness was created
on epoxy modified cotton fabric by applying amino and epoxy-functionalized silica
nanoparticles on textile. Then the surface energy of treated textile was further lowered by post treating with stearic acid and the superhydrophobic textile with water
contact angle nearly 170° was obtained.
Along with pad-dry-cure method, spraying have also been used for the coating
of modified nanoparticles on the textile. SiO 2 nanoparticles dispersed in toluene,
functionalized with trichlorododecylsilane that grafted dodecyltrichloro group on
nanoparticle surface were sprayed on cotton after drying at room temperature the
modified textile confirmed superhydrophobicity exhibiting water contact angle more
than 160° also with contact angle hysteresis less than 10° [64].
For textile modification by attachment of nanomaterials various methods have
been adopted and reported with merits and demerits of every technique.
The sol-gel method have always been most well-known and well applied to adhere
nanoparticles with textile to make it superhydrophobic. But, the main issue with
M. Ashraf and S. Riaz
a research was done in which silanes with different chain lengths were used
to lower the surface energy along with silica nanoparticles. Cross linker was
added to enhance the durability of nanoparticles. From the study it was confirmed that n-dodecyltrimethoxysilane was the best hydrophobe due to longest
chain length among seven repelling agents such as n-octadecyltrimethoxysilane,
n-dodecyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-butyltrimethoxysilane,
n-ethyltrimethoxysilane, n-octyltrimethoxysilane, and methyltrimethoxysilane [44].
As the nanoparticle do not have the affinity for textiles, therefore, some binders
have been used [58–60] to increase their adhesion with the substrate mentioned
previously in this chapter. Due to the application of binders the comfort and properties like tear strength have been compromised [61]. Therefore, there was a need
to find a way out to improve the durability without affecting the inherent characteristics of the textile. The researchers tried to functionalize the nanoparticles
with silane coupling agents to directly bind them with the textile without using any
crosslinker. Riaz et al. [1] investigated the comfort properties by developing highly
durable superhydrophobic textiles by application of 3-(Trimethoxysilyl) propylN,N,N-dimethyloctadecyl ammonium chloride and 3-Glycidoxypropyl)trimethoxysilane modified SiO 2 nanoparticle at cotton fabric. It was found that water contact
angle of nearly 150° was obtained without compromising the comfort properties and
functionality up to 20 industrial washing cycles was obtained.
To make the surface very near to lotus effect binary hierarchical roughness in more
than one layer was also tried to be created at the textile to attain maximum WCA.
In this regard, different sizes of SiO 2 nanoparticles were used with two silanes.
First layer of 3-aminopropyl triethoxysilane functionalized SiO 2 nanoparticles was
applied onto textile and then 2nd layer of 3-glycidoxypropyltrimethoxysilane functionalized SiO 2 nanoparticles was deposited onto the 1st layer. The deposition of
different sized nanoparticles created the binary hierarchical roughness at the substrate. Due to direct relationship between surface morphology, surface roughness
and water contact angle it was possible to tailor the water contact angle [62]. Xue
et al. [63] also presented same type of study in which binary roughness was created
on epoxy modified cotton fabric by applying amino and epoxy-functionalized silica
nanoparticles on textile. Then the surface energy of treated textile was further lowered by post treating with stearic acid and the superhydrophobic textile with water
contact angle nearly 170° was obtained.
Along with pad-dry-cure method, spraying have also been used for the coating
of modified nanoparticles on the textile. SiO 2 nanoparticles dispersed in toluene,
functionalized with trichlorododecylsilane that grafted dodecyltrichloro group on
nanoparticle surface were sprayed on cotton after drying at room temperature the
modified textile confirmed superhydrophobicity exhibiting water contact angle more
than 160° also with contact angle hysteresis less than 10° [64].
For textile modification by attachment of nanomaterials various methods have
been adopted and reported with merits and demerits of every technique.
The sol-gel method have always been most well-known and well applied to adhere
nanoparticles with textile to make it superhydrophobic. But, the main issue with