CELLULOSE CHEMISTRY AND TECHNOLOGY Cellulose Chem. Technol., 50 (5-6), 711-719 (2016) COLD PLASMA TREATMENT OF COTTON AND VISCOSE FABRICS IMPREGNATED WITH ESSENTIAL OILS OF LAVANDULA ANGUSTIFOLIA AND MELALEUCA ALTERNIFOLIA SÓNIA SOUSA, * CARLA GAIOLAS, * ANA P. COSTA, * CECÍLIA BAPTISTA ** and MARIA E. AMARAL * * FibEnTech and Department of Chemistry, University of Beira Interior, 6201-001 Covilhã, Portugal ** IPT –Polytechnic Institute of Tomar, 2300-313 Tomar, Portugal Corresponding author:Maria E. Amaral,mecca@ubi.pt Dedicated to the 50 th anniversary of Cellulose Chemistry and Technology, and its systematic work in the cellulose and lignin industry field In this research, the synergetic effect of cold plasma treatment and two essential oils, namely Lavandula angustifolia (lavender) and Melaleuca alternifolia (tea tree), on the physicochemical properties of cotton and viscose fabrics were investigated. The chemical changes on the fabric surface caused by the treatments were investigated by contact angle measurements, surface energy calculation and ATR-FTIR analysis. In addition, the content of carboxyl, aldehyde and hydroxyl end groups was assessed. The antimicrobial activity of the untreated and treated fabrics was evaluated. The results showed that grafting with monomers existing in lavender or tea tree oil leads to an increase of the water contact angle and its stability over time. It was observed that the treatments with essential oils increase the carboxyl groups content, except for the viscose treated with lavender oil. It was also demonstrated that the cotton fabric immersed into lavender oil exhibited antimicrobial activity against S. aureus. However, further plasma treatment resulted in the loss of antibacterial properties. Keywords: Lavandula angustifolia, Melaleuca alternifolia, cold plasma, textile fabrics, physicochemical properties, antimicrobial activity. INTRODUCTION Nosocomial infection currently represents not only a serious concern to the competent health agencies, but also a problem with social, ethical and legal implications in relation to the lives of patients. In order to reduce infection rates, many strategies and different methods have been developed in the last several decades. 1 Improved hygiene and healthcare standards have a great impact on the development of hygiene and health care products. Therefore, textiles related to health care have started receiving much attention, thus increasing the need for antimicrobial treatment of fabrics. 2,3 Cotton and viscose fabrics, in addition to being used in everyday clothing, are also applied in the medical and technical textile field. 3-7 However, these cellulosic textiles are susceptible to the microbial attack during use and storage. The growth of microbes on textiles has the potential to cause cross infection, transfer of diseases, allergic reactions, and unpleasant odours on humans. 8 These detrimental effects can be controlled by antimicrobial finishing of the textile fabrics, which includes treatment with nano-scale metal or metal oxides, quaternary ammonium salt, antibiotics, natural extracts, essential oils or components of essential oils. 2,5,6,9-13 The use of the latter has become popular, as numerous studies have been published on their antimicrobial activities against many different types of microorganisms. 4,14-25 Essential oils represent complex mixtures of chemical compounds (such as phenols, aldehydes, ketones, alcohols, esters, ethers or hydrocarbons)