Elsevier

Applied Surface Science

Volume 455, 15 October 2018, Pages 924-930
Applied Surface Science

Full Length Article
Pore size effect on one-way water-transport cotton fabrics

https://doi.org/10.1016/j.apsusc.2018.06.007Get rights and content

Highlights

  • Directional water transport fabrics were prepared by an electrospray technique.

  • Fabric pore size decides the maximum one-way water transport capacity of fabric.

  • Fabrics with smaller pores show larger one-way transport capacity.

Abstract

Fabrics with spontaneous one-way water transport property have received much attention in scientific and industrial communities in the recent years. However, limited knowledge is available about how to control and adjust directional water transport capacity on fabrics. In this study, we have prepared one-way water transport fabrics using three plain-woven cotton fabrics, which have different pore sizes, as substrates. An electrospray technique was employed to deposit hydrophobic coating on one side of the fabrics. One-way water transport property was attained when the coating thickness was in the range of 9.0–23.9 μm. The fabric pore size was found to be a critical factor deciding the maximum one-way water transport capacity that can be achieved on the fabric. With the same coating thickness, the fabric with smaller pores showed larger one-way transport capacity. These novel results may be useful for designing high performance one-way water transport fabrics for various applications.

Introduction

Directional water transport (OWT) (also called one-way water transport) guided by surface wettability or structural feature has been observed on Namib Desert beetle’s wings [1], [2], spider silk [3], [4], cactus [5], rice leaf [6], Strelitzia reginae leaf [7], and the peristome surface of Nepenthes alata [8]. Inspired by these natural phenomena, fabrics with advanced moisture transport ability have been developed. Directional water transport fabrics allow water to transfer automatically from one fabric side to the other without use of external energy, but hinder moisture transport in the opposite direction [9], [10], [11]. They show potential applications for summer clothing, sportswear, workwear, medical and technical fabrics.

Several papers have been reported on the preparation of OWT fabrics based on either creating a hydrophobicity-to-hydrophilicity gradient across the substrate thickness or forming a hydrophobic layer on a hydrophilic fabric substrate. For examples, Wang et al. and Zhou et al. [10], [12], [13] from our group and Kong et al. [14] have separately reported a two-step method involving applying a hydrophobic material on the entire fabric and subsequently photo-degrading to prepare wettability gradient-type OWT fabrics. Tian et al. [11] prepared an OWT fabric through one side chemical vapor deposition. Wu et al. [15] prepared a OWT fibrous film by combining a hydrophobic polyurethane with a hydrophilic crosslinked poly(vinyl alcohol) fibrous layers. Cao et al. [16] used a hydrophobic copper mesh and a hydrophilic cotton fabric to prepare an OWT fibrous composite for fog collection. Li et al. [17] reported a spraying method to apply TiO2 sol–gel on one side of cotton fabric to obtain day-light-triggered OWT fabrics. These studies were chiefly qualitative, lacking quantitative analysis of liquid transport performance. Recently, Zeng et al. [9] in our group prepared one way water transport fabric using a single-side electrospraying method to deposit modified SU-8 on a hydrophilized polyester fabric. By precisely controlling the coating depth on one side of the fabric, they showed that hydrophobic layer thickness played a key role in deciding the one-way water transport ability. Despite of these studies, the effect of hydrophilic layer fibrous structure on OWT property has less been reported.

In this study, we have prepared OWT fabrics using three plain woven cotton fabrics, which have different pore sizes, as substrates, and elucidated the effect of hydrophilic layer fibrous pore size on the OWT ability. An electrospray method was employed to form a porous hydrophobic layer on one side of the fabrics. This study differs to the previous work (i.e. Zeng et al. [9]) in coating materials, fibrous substrate, and coating morphology, though they both use an electrospraying technique. In Zeng’s work, SU-8 was used as coating material and hydrophilic polyester fabric as substrate. However, in our current study, PVDF-HFP/FAS was used as coating materials. We used cotton fabrics of different pore sizes as substrates, to adjust the pore size in the hydrophilic fabric matrix. It was found that pore size was a critical parameter affecting OWT property. It decided the maximum OWT capability that can be achieved on fabric. With the same hydrophobic layer thickness, the fabric with smaller pores showed larger OWT capacity. These novel results may be useful for designing high performance OWT fabrics.

Section snippets

Materials

Three plain woven cotton fabrics marked as CF-1 (104 g m−2, 240 μm), CF-2 (104 g m−2, 290 μm), CF-3 (130 g m−2, 360 μm) were purchased from the local market. Fluorinated alkyl silane (FAS, tridecafluorooctyl triethoxysilane, Dynasylan F 8261) from Jianyi Chemicals Imp & Exp, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP, Mw ≈ 400,000) from Aldrich, N, N′-dimethylformamide (DMF), sodium chloride (NaCl) from Tianjin Kemiou Chemical Regent, sodium hydroxide (NaOH) and Rhodamine B

Results and discussions

Fig. 1a shows the chemical structures of PVDF-HFP and FAS, and the one side electrospray procedure. During electrospraying, PVDF-HFP/FAS solution split into tiny droplets and deposited mainly on one side of the cotton fabric. Fig. 1b shows the digital photos of the cotton fabric before and after the spraying treatment. The coating on the electrosprayed side (referred as “E-side”) looked uniform, whereas the un-electrosprayed side (referred as “U-side”) still maintained the original morphology.

Conclusion

We have prepared OWT cotton fabrics by electrospraying a thin layer of hydrophobic micro-nano porous structure on fabric surface, and demonstrated that mean pore size and hydrophobic layer thickness play vital roles in deciding the OWT index. When the hydrophobic layer thickness was between 9.0 μm and 23.9 μm, fabrics show one-way water transport feature. The hydrophilic layer fibrous pore size played a critical factor deciding the maximum OWT capacity of the fabric, and the MMT results

Acknowledgements

This work was supported by the National Natural Science Foundation of China (grant numbers 51573136), Natural Science Foundation of Tianjin (grant numbers 12JCYBJC17800), and the Science and Technology Plans of Tianjin (grant numbers 15PTSYJC00230, 15PTSYJC00240, 15PTSYJC00250) and Australian Research Council Industrial Transformation Research Hub project (ARC IH140100018).

References (34)

  • F. Liu et al.

    Carbohydr. Polym.

    (2014)
  • S. Wongchitphimon et al.

    J. Membr. Sci.

    (2011)
  • H.X. Wang et al.

    J. Membr. Sci.

    (2007)
  • M. Spasova et al.

    Appl. Surf. Sci.

    (2016)
  • D.Y. Hou et al.

    J. Wang. Sep. Purif. Technol.

    (2017)
  • A.R. Parker et al.

    Nature

    (2001)
  • L. Zhai et al.

    Nano Lett.

    (2006)
  • Z.B. Huang et al.

    Soft Matter

    (2011)
  • Y.M. Zheng et al.

    Nature

    (2010)
  • J. Jie et al.

    Nat. Commun.

    (2012)
  • L. Feng et al.

    Adv. Mater.

    (2002)
  • E. Mele et al.

    Langmuir

    (2012)
  • H.W. Chen et al.

    Nature

    (2016)
  • C. Zeng et al.

    Adv. Mater. Interfaces

    (2016)
  • H. Zhou et al.

    Sci. Rep.

    (2013)
  • X.L. Tian et al.

    Adv. Func. Mater.

    (2014)
  • H.X. Wang et al.

    J. Mater. Chem.

    (2010)
  • Cited by (0)

    View full text