Textile fibers hydrophobic/hydrophilic, properties

In this chapter, a series of recent results in surface modification of various surfaces employing the macromolecular anchoring layer approach was overviewed. It was demonstrated that the approach could be used as a virtually universal method for grafting of functional polymer brushes. The properties of the bmshes can be controlled by polymer nature, structural and morphological factors, and external stimuli. The polymer grafting technique developed can be readily applied to surface modification of fibers and textiles, leading to generation of hydrophobic, hydrophilic and switchable fibrous materials. 

As discussed above, increases in wettability have been one of the primary and well-recognized surface effects obtained on textiles with plasma systems which utilize oxygen, air, and ammonia plasmas. Other recognized benefits are enhancements in surface desizing and capillarity of natural textile fibers such as wool and cotton. Particular to the hydrophobic properties of wool fiber surfaces, we have summarized that these can be transitioned to hydrophilic to obtain a reduced felting effect. However, if there is interest in moving toward an inverse effect, hydrophobic properties, as observed on cotton fabrics, can be also induced with prescriptions of type and proportions of gas chemistries used in the plasma reaction [33]. 

One important lesson is that measurement of the apparent contact angle of a sessile drop will not give a true measure of the wettability - or even surface free energy - of the fiber surface. The apparent contact angle will always be affected by microscopic surface property (i.e. fiber surface), macroscopic surface geometry (fabric), and capillary effects. In case of hydrophilic substrates the sessile droplet will penetrate the porous textile, typically in seconds, and thus effectively prohibit the measurement. On a hydrophobic surface, the apparent contact angle will always differ from the true contact angle on the fiber surface. Capillary effects occur even on hydrophobic substrates and compete with evaporation of the liquid. 

The water in the textile is composed of water soaked into the fibers, water adsorbed on the fiber surface, and water in the pores of the textile. The water-retention capability is thus influenced by both the hydrophilic or hydrophobic properties and the soaking behavior of the fiber material. 

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