Enhancement of anatase functionalization and photocatalytic self-cleaning properties of keratins by microwave-generated plasma afterglow

A microwave-generated plasma afterglow (MWGPA) treatment was applied to keratin fibers to improve their adhesion to anatase nanocrystals by modifying their surface chemical and physical structure. The induced photocatalytic self-cleaning property has significantly been improved by 70% as evidenced by complete stain decomposition in 6 h only. The effects of gas mixtures, gas flow, treatment distance, treatment duration and power flow of the MWGPA treatment on keratin's surface were investigated. The MWGPA-induced alteration of keratin's surface structure resulted in an increase in the uptake of anatase crystals and thus enhanced photocatalytic self-cleaning activities. The contact angle, absorption time, deposition behavior, adhesion and stability of anatase coating of keratin fibers are discussed. The anatase uptake and coating uniformity were characterized quantitatively using Time-of-Flight Secondary Ion Mass Spectrometry. This efficient and low energy plasma surface activation approach demonstrated potential toward the practical application of anatase in keratinous materials.