Atomic layer deposition (ALD) of aluminum oxide on nonwoven polypropylene and woven cotton fabric materials can be used to transform and control fiber surface wetting properties. Infrared analysis shows that ALD can produce a uniform coating throughout the nonwoven polypropylene fiber matrix, and the amount of coating can be controlled by the number of ALD cycles. Upon coating by ALD aluminum oxide, nonwetting hydrophobic polypropylene fibers transition to either a metastable hydrophobic or a fully wetting hydrophilic state, consistent with well-known Cassie-Baxter and Wenzel models of surface wetting of roughened surfaces. The observed nonwetting/wetting transition depends on ALD process variables such as the number of ALD coating cycles and deposition temperature. Cotton fabrics coated with ALD aluminum oxide at moderate temperatures were also observed to transition from a natural wetting state to a metastable hydrophobic state and back to wetting depending on the number of ALD cycles. The transitions on cotton appear to be less sensitive to deposition temperature. The results provide insight into the effect of ALD film growth mechanisms on hydrophobic and hydrophilic polymers and fibrous structures. The ability to adjust and control surface energy, surface reactivity, and wettability of polymer and natural fiber systems using atomic layer deposition may enable a wide range of new applications for functional fiber-based systems.

Atomic layer deposition (ALD) has recently been demonstrated as a novel method for the creation of nanoscale coatings on fiber-based materials. The ALD process has proven effective in altering the surface energy of both woven and nonwoven materials. In this work, the effect of fabric weave geometry on the behavior of ALDmodified fabrics has been studied. Aluminum oxide ALD was used to modify a series of fabric weaves which were then analyzed using sessile contact angle measurements. The experimental results demonstrated the ability of the ALD process to modify the surface energy of a variety of weave structures, regardless of the inter-fiber spacing within the yarns. At the same time, the amount of fiber spacing, which is influenced by the weave geometry, changes the effect of the ALD coatings on fabric hydrophobicity and hydrophilicity. The results of this work demonstrate the versatility of the ALD process when modifying woven fabric structures and its potential as a method for nanoscale textile finishing.