Fabrication of superhydrophobic cotton fabrics by a simple chemical modification
Cellulose
Fabrication of superhydrophobic cotton fabrics by a simple chemical modification
0 M. Nowicki Institute of Physics, Poznan ́ University of Technology , Piotrowo 3, 60-965 Poznan ́ , Poland
1 H. Maciejewski Faculty of Chemistry, Adam Mickiewicz University , Umultowska 89b, 61-614 Poznan ́ , Poland
2 M. Przybylak H. Maciejewski (&) A. Dutkiewicz I. Da ̨bek Poznan ́ Science and Technology Park , Rubiez_ 46, 61-612 Poznan ́ , Poland
Hydrophobization of cotton fabrics was carried out with the use of bifunctional polysiloxanes with various contents of functional groups. Polysiloxanes contained in their structure groups capable of bonding to substrates (trialkoxysilyl or glycidyl ones) and fluoroalkyl groups showing surface activity. Two methods of surface modification were compared: (1) a one-step method via the chemical modification of fabrics with solutions of bifunctional polysiloxanes and (2) a two-step method-via preliminary modification of fabrics with silica sol followed by chemical modification with solutions of bifunctional polysiloxanes. The hydrophobicity was determined by measuring the water contact angle by drop profile tensiometry. Changes in the surface topography were examined by scanning electron microscopy. Superhydrophobic fabrics were obtained by a simple one-step method by the chemical modification in solutions of bifunctional polysiloxanes. The fabrics maintained their superhydrophobic properties even after multiple washings. The modification does not cause any changes visible to the naked eye, such as stiffening, color changes or a decrease in mechanical properties.
Superhydrophobicity; Cotton fabrics; Polysiloxane; Sol-gel; Dip coating
Introduction
In recent years, there has been increased interest in the
research and production of highly hydrophobic natural
textiles due their unique characteristics such as
selfcleaning, anti-contamination and anti-sticking
(Ivanova and Zaretskaya 2011; Erasmus and Barkhuysen
2009; Xu et al. 2011)
. Natural fibers consists mainly of
cellulose, hemicelluloses, lignins and pectins, the
structures of which contain, among others, hydroxyl
groups. In spite of the many advantages of natural
fibers, they cannot be applied for many purposes
because of their high polarity and hydrophilicity
(resulting mainly from the presence of hydroxyl
groups). The excessive moisture absorbability
weakens materials made from natural fibers (a decreased
adhesion), and at the same time it favors the growth of
microorganisms (fungi, molds, bacteria). To bypass
the above disadvantages, natural fibers are subjected to
specific modifications of their surfaces aimed at
creating an appropriate hydrophobic barrier.
Nonwettable textiles with a high water contact angle
(WCA), particularly the superhydrophobic ones (i.e.,
those with WCA[150 ), are a contemporary research
topic because of the significant commercial and
industrial importance of low-surface-free-energy
cellulosic materials for different apparel and technical
applications such as protective clothing, stain-resistant
fabrics and clothing for medical personnel. The
wettability of a surface depends on two factors:
(1) its chemical composition and (2) its structure
(roughness). Different techniques for producing rough
surfaces were developed by imitating nature
(biomimetics); however, in textile production most
of them cannot be recreated. Only the introduction of
nanotechnology processes, such as electrospinning
(Hutmacher and Dalton 2011)
, plasma treatment
(Kan
et al. 2011; Mihailovic´ et al. 2011; Patin˜o et al. 2011;
Sun and Qiu 2012; Vasiljevic´ et al. 2013)
and sol–gel
technology
(Mahltig 2011; Bae et al. 2009; Vilcˇnik
et al. 2009; Zhu et al. 2011; Zhao et al. 2010; Simoncˇicˇ
et al. 2012; Shateri-Khaliladad and Yazdanshenas
2013; Berendjchi et al. 2011; Chen et al. 2010)
, have
enabled breakthroughs in the creation of
superhydrophobic and self-cleaning textiles. In particular, the
latter are very popular because the production and
application of particles and nanoparticles on a surface
make it possible to easily control its roughness. The
mild preparation conditions offer the possibility of
incorporating a wide range of labile organic species.
Moreover, sol–gel-derived materials exhibit tunable
porosity, transparency, hardness and good thermal
stability
(Basu et al. 2010; Xu et al. 2010)
. There are
several kinds of inorganic nanosize particles, such as
SiO2, TiO2 and ZnO, which can be introduced onto the
textile surface. However, this method only enables
producing a suitable roughness of the surface, whereas
to make it strongly hydrophobic, a chemical
modification is necessary. Sometimes in the sol–gel process
compounds such as, e.g., alkyltrialkoxysilanes
(Mahltig and Bo¨ttcher 2003; Xu et al. 2011;
ShateriKhaliladad and Yazdanshenas 2013; Pipatchanchai
and Srikulkit 2007)
or functionalized silicas
(Leng
et al. 2009; Xue et al. 2009; Zhang and Wang 2013;
Hoefnagels et al. 2007)
are directly em (...truncated)