|Rr. Wiwiek Eka Mulyani||1. Doctoral Program of Engineering Physics, Faculty of Industrial Technology, Institut Teknologi Bandung, Bandung 40132, Indonesia, 2. Textile Chemistry Department, Polytechnic of Textile Technology,|
|Ahmad Nuruddin||Advanced Functional Materials Research Group, Faculty of Industrial Technology, Institut Teknologi Bandung, Bandung 40132, Indonesia|
|Suprijanto||Instrumentation and Control Research Group, Faculty of Industrial Technology, Institut Teknologi Bandung, Bandung 40132, Indonesia|
|Bambang Sunendar Purwasasmita||Laboratory of Advanced Materials Processing, Faculty of Industrial Technology, Institut Teknologi Bandung, Bandung 40132, Indonesia|
The hydrophilicity of polyester fabric surfaces has
been modified using silica-chitosan nanocomposites. The silica-chitosan
nanocomposite was synthesized by the sol-gel method from sodium silicate and
various chitosan concentrations of 0 – 1.5% at a pH of 3 – 5. A single jersey
knitted polyester fabric was coated by silica-chitosan nanocomposite using the
pad-dry-cure method. It was found that the chitosan concentration and the
solution pH controlled the formation of various size distributions of sphere
nanocomposites with an average size of 96.0-201nm. The coated polyester fabric
with sphere silica-chitosan exhibits a rough surface and produces a contact
angle approaching 0°, facilitating the polyester fabric's speed-up water
absorption and hydrophilic properties.
Chitosan; Hydrophilic; Nanocomposite; Polyester; Sodium silicate
Synthetic fibers such as polyester are the most popular and common fiber used in activewear and sportswear. It is cheap, easy to manufacture, and has excellent washing and wearing properties (Shishoo, 2005). Polyester fibers also have a good wicking rate and better dimensional stability (Ramakrishnan and Jagannathan, 2018). However, the fiber is generally hydrophobic and has a much lower water absorption capacity. Polyester deficiencies are usually overcome by improving the wicking ability through chemical treatment, which is achieved by applying a hydrophilic coating to each polyester filament. The resulting hydrophilic surface allows moisture to migrate along the outer surface of the filament.
Researchers have tried to modify the polyester surface's hydrophilicity, for example, by blending polyester with cellulosic (Zaman et al., 2013; Troynikov and Wardiningsih, 2011) and hydrolysis of the polyester surface using enzymes and surfactants (Gao et al., 2017). Wu et al. (2014) modified the polyester surface using cutinase treatment. Natarajan and Moses (2012) used polyvinyl alcohol to modify the polyester hydrophilicity. Recently Chen, Haase, and Mahltig (2019) modified a polyester fabric surface using a silica-chitosan composite, which succeeded in enhancing the hydrophilicity of the polyester fabric surface by measuring the sink-in time. They use tetraethoxysilane (TEOS) as primary precursors for preparing a spherical shape of silica nanoparticles. However, considering the material cost, alkoxide may not be commercially viable in the textile industry.
Sodium silicate has been considered as an alternative inexpensive silica precursor to substitute expensive alkoxide compounds (Hwang, Lee, and Chun, 2021). Researchers have prepared diverse nanostructured silica from sodium silicate (Owoeye, Abegunde, and Oji, 2021; Chiang et al., 2017, 2011; Jesionowski and Krysztafkiewicz, 2002). However, they synthesized sodium silicate precursor in an alkaline medium to produce non-agglomerated silica nanoparticles. In contrast, the synthesis of silica from sodium silicate in acid conditions tends to result in agglomeration (Zulfiqar, Subhani, and Husain, 2016).
Chitosan is a unique
cationic polysaccharide that can easily be modified with chemicals, radiation,
and enzymes (Barleany et al.,
2020; Usman et al., 2018). It is a
biodegradable biopolymer used in an environmentally friendly synthesis process (Lim et al.,
2021; Usman et al., 2018;
Kusrini et al., 2015). As a
biopolymer, chitosan is a useful polymer for synthesizing metal oxide and
encapsulating small particles (Lim et al.,
2021; Matusiak, Grzadka, and
Bastrzyk, 2018). Recent
interest in chitosan has increased due to its structure's presence of main
amino groups that acts as crosslinker (Chen, Haase, and Mahltig, 2019; Haerudin et al.,
This study is aimed to synthesize silica-based chitosan nanocomposites using the sol-gel method from sodium silicate and chitosan. The relationship between pH and chitosan concentration in forming silica-chitosan composites was investigated. The effects of silica-chitosan nanocomposite coating on the polyester fabric surface were demonstrated.
Knitted polyester fabric having a single jersey knitted design, mass per unit area 150.6 g/m2, thickness 0.57 mm, yarn count 9.61 tex, 51 courses per inch, 43.67 wales per inch was used as a substrate for coating. The fabric samples were knitted on a single Fukuhara machine from 100% polyester filament yarn. Ethanol (99.9%) and acetic acid (98%) were obtained from Merck. Sodium silicate, chitosan, and distilled water were obtained from a local market. All chemical reagents were used without further purification.
2.2. Preparation of precipitated silica-chitosan
Precipitated silica-chitosan was prepared by mixing sodium silicate with ethanol and distilled water under continuous magnetic stirring. The solution was then divided into three equal parts. Acetic acid was titrated to each solution to adjust the pH value to 3, 4, and 5. Chitosan solution with concentrations of 0%, 0.5%, 1%, and 1.5% was added to the different pH of sodium silicate solutions. Finally, white precipitated silica-chitosan was collected by centrifugation and filtering and then dried in an electric oven at 50oC for 2 h.
2.3. Coating silica-chitosan on polyester fabric
Five pieces of polyester fabrics were coated with silica-chitosan nanocomposite using a pad-dry-cure method. The polyester fabric was padded for double-nip and double-dip in a 100 mL bath with a wet pick-up ratio of 70%. The silica-chitosan-treated polyester fabric was then dried at 100oC for 1 min and cured at 150oC for 2 min.
2.4. Characterization of silica-chitosan nanocomposite
The silica-chitosan nanocomposite and coated fabric surface morphology were observed using a Hitachi TM SU-3500 Scanning electron microscope (SEM). The functional groups of nanocomposites were analyzed using a Shimadzu Prestige 21 Fourier-transform infrared (FTIR) Spectrophotometer. The microstructure of the samples was measured using a Bruker X-ray diffractometer (XRD) at 40 kV with a radiation source
Characterization of the coated fabric surface
The polyester fabric surface was evaluated, including water contact angle and absorption. The wettability or absorbency of polyester fabrics was examined before and after treatment using the AATCC test method 79 (AATCC, 2018). In brief, a drop of water is dropped from a fixed height onto the surface of a test specimen. The time required for the specular reflection of the water drop to disappear is measured and recorded as sink-in time. The water contact angle on polyester fabric before and after treatment was measured using a Kyowa KYOWA interFAce Measurement and Analysis System. The volume of the water droplet was set at
3.1. The morphology of silica-chitosan
SEM examined the surface morphology of the silica and silica-chitosan products; representative images are shown in Figure 1. At pH 3, the silica product synthesized without chitosan (pH 3 Ch 0) depicted a loose spherical particle of various sizes from 50 nm to 200 nm. With increasing chitosan concentration (pH 3 Ch 0.5 – 1.5), the surface morphology did not change, but the silica-chitosan product decreased the size (96.0 nm – 120.3 nm) and was narrowly distributed. The surface morphology of the silica-chitosan product prepared at pH 4 and 5 have the same trend as the surface morphology of the silica-chitosan product prepared at pH 3.
Figure 1 SEM images of silica and silica-chitosan particles synthesized at different pH and chitosan concentrations
To reveal the particle size distribution
of the silica and silica-chitosan, the particle images in Figure 1 were
analyzed using ImageJ software. Figure 2 shows the particle size distribution
of the silica and silica-chitosan products prepared at pH 3 – 5. It can be seen
from Figure 2 that the silica and silica product prepared at low pH tends to
have a narrow particle size distribution. This is because the pH value strongly
influences the hydrolysis and condensation reactions in the sol-gel process.
Under acidic conditions, the hydrolysis reaction rate is faster than the
condensation reaction rate to produce a small particle size (Barker et.al.,
2022; Budnyak et al., 2015). Therefore, the average particle size of the silica
(119.5 nm) and silica-chitosan (96 - 120.3 nm) compared at pH 3 is smaller than
the silica (182 nm and 165.5 nm) and silica-chitosan (126.6 – 144.2 nm and
177.6 – 201.4 nm) prepared at pH 4 and 5, respectively. It is also clearly
noticed in Figure 2 that the average size of silica prepared without chitosan
is larger than that prepared by adding chitosan. Increasing the concentration
of chitosan tends to enhance the size of silica-chitosan. The higher the concentration
of chitosan involved in the reaction, the larger the size of the
silica-chitosan formed. In an acidic environment, the chitosan acts as a
crosslinker that connects the formed silica particles (Pierog, Gierszewska-Druzynska, and Ostrowska-Czubenko, 2009). The amine group of chitosan (NH2) is
protonated to be positively charged to form -NH3+ ion,
while silica is negatively charged. The interactions between the negatively
charged silicon oxide surface and the positively charged polymer chains formed
silica-chitosan nanocomposite (Chen,
and Mahltig, 2019; Budnyak et al., 2015).