Superphobicity/philicity Janus Fabrics with Switchable, Spontaneous, Directional Transport Ability to Water and Oil Fluids

Abstract

Herein we demonstrate that switchable, spontaneous, directional-transport ability to both water and oil fluids can be created on fabric materials through wet-chemistry coating and successive UV irradiation treatment. When the fabric showed directional transport to a liquid, it prevented liquids of higher surface tension from penetration, but allowed liquids of lower surface tension to permeate, from either side. The directional transport ability can be switched from one fluid to another simply by heating the fabric at an elevated temperature and then re-irradiating the fabric with UV light for required period of time. By attaching liquid drops vertically upwards to a horizontally-laid fabric, we further demonstrated that this novel directional fluid transport was an automatic process driven by surface property alone, irrespective of gravity's effect. This novel fabric may be useful for development of “smart” textiles and functional membranes for various applications.

Directional Water Transport Fabrics with Durable Ultra‐High One‐Way Transport Capacity

“…This result is in good accordance with our previous reports. [13] When the loading was higher than 1.0 g m −2 (i.e., coating depth 62 μm), the breakthrough pressure on the uncoated side was larger than that on the SU-8 coated side ( Figure S9, Supporting Information). We also calculated the breakthrough pressure difference (∆P uncoated-coated ) between the uncoated and the SU-8 coated sides ( Figure S10, Supporting Information).…”

“…In our previous paper, we have pointed out that this directional water transport feature originates from asymmetric wettability across the thickness. [11][12][13] In the previous studies, we have proposed the mechanism of directional fluid transport. [11,13] Water transport through the SU-8 sprayed fabric is illustrated in Figure 5.…”

“…[11][12][13] In the previous studies, we have proposed the mechanism of directional fluid transport. [11,13] Water transport through the SU-8 sprayed fabric is illustrated in Figure 5. It is easy to understand that water can easily spread into the hydrophilic matrix when it is dropped on the un-sprayed side.…”

“…For example, Wang et al and Zhou et al from our group [11][12][13] and Kong et al [14] have separately reported the preparation of directional water transport fabrics through a two-step process involving superhydrophobic treatment of fabric followed by one-side photo-degradation to create a hydrophobicity-to-hydrophilicity gradient through fabric thickness. Zhang et al [15] used a phase separation method to form a hydrophilic-to-hydrophobic gradient membrane showing directional water transport ability.…”

“…Directional water transport through fabrics is ascribed to isotropic wettability along the fabric thickness. [3,11,13,14,19] Directional water transport fabrics show difference in water breakthrough pressure on the two fabric sides. [11][12][13]17] However, the lack of effective technique to precisely control the coating layer thickness has confined the study on the role of hydrophobic fabric layer thickness in forming directional water transport on conventional fabrics.…”