Preparation and characterisation of novel phospholipid cationic liposomes to improve the alkaline hydrolysis and dyeability of polyester fabric Manal M El-Zawahry* and Fatma Abdelghaffar Textile Research Division, National Research Centre, El-Behouth St. Dokki, Cairo, PO, 12622, Egypt Email: manalzawahry@yahoo.co.uk Received: 12 August 2011; Accepted: 30 July 2012 Three novel cationic liposomes were prepared from commercial soybean lecithin (neutral liposome) and stearylamine (cationic liposome) as a catalyst or accelerating agent for the alkaline hydrolysis of polyester fabric. The formation of 1:1, 1:6 and 1:12 cationic liposomes was confirmed by transmission electron microscopy, nitrogen content and Fourier Transform-infrared spectroscopy. Factors affecting the alkaline hydrolysis performance of polyester fabric in the presence and absence of cationic liposomes were investigated. Size measurements of the three cationic liposomes showed that the vesicle size was 27.88 nm for the 1:1 cationic liposome, 15.57 nm for 1:6 and 10 nm for 1:12, in comparison with 50 nm for neutral liposome. The results showed that alkaline hydrolysis in the presence of cationic liposomes improves the hydrophilicity and dyeability of polyester fabric and creates more carboxylic groups on the fabric. The silky polyester fabric was characterised by scanning electron microscopy, tensile strength, elongation at break, crease recovery angle and surface roughness to prove the success of the cationic liposomes as accelerating agents in the alkaline hydrolysis process. The results also indicate that the colour strength of hydrolysed polyester fabric in the presence of cationic liposomes dyed with disperse dye was slightly higher than that obtained in the absence of cationic liposomes and with unhydrolysed fabric. Furthermore, the fastness properties of hydrolysed polyester in the absence and presence of cationic liposomes do not vary. Coloration Technology Society of Dyers and Colourists Introduction Polyester fibres made of polyethylene terephthalate (PET) are important synthetic fibres used for the production of textiles. They are widely used for outdoor, sports and active wear, as well as for protective clothing, and they are also used for the production of medical textiles, automotive parts and in numerous technical applications. The fibres show excellent strength properties, high hydrophobicity and resistance to chemicals, together with low abrasion and shrinking properties. However, some complicated processes are employed to obtain value-added properties of PET in textile finishing: cospinning [1], physical coating [2], plasma discharge [3–5], alkaline and enzymatic treatments [6–8], graft polymerisation [9,10], etc. Some of these methods have limited practical use, and they are frequently accompanied with hardening of the feel of PET or elevated production costs. Accordingly, there has been great demand for finishing technology that could be applied to PET fibre more easily and efficiently. Owing to its chemical structure, lecithin has an affinity for natural materials such as textile fibres [11]. Lecithin is a phospholipid and has the property of being able to form liposomes. Lecithin technology in the form of liposomes is used to improve textile dyeing and finishing performance and reduce effluent pollution [12–14]. Liposomes are defined as having a structure composed of lipid vesicle bilayers enclosing a volume. These structures are usually made up of phosphatidylcholine (PC), which has a hydrophilic part consisting of phosphate and choline groups and a hydrophobic part composed of two hydrocar- bon chains that vary in length. Some work has already been reported with encouraging results on the potential applica- tion of liposomes in PET dyeing. This work has investigated liposomes as a dispersion vehicle for encapsulating disperse dye molecules [15–17] and/or as a dispersing agent in PET dyeing [18]. The surface charge of liposomes can be modified by the incorporation of positively charged lipids, such as stearylamine (SA), or negatively charged lipids, such as dicetylphosphate, phosphatidylglycerol or phos- phatidylserine [19]. In this study, three cationic liposomes (Cat Ls) were prepared, composed of commercial soybean lecithin and SA with a molar ratio of 1:1, 1:6 and 1:12, which act as catalysts or accelerating agents for the alkaline hydrolysis of PET fabrics to produce Kashmir silk-like fabrics. The study deals with the characterisation of the three Cat Ls in terms of chemical interaction (Fourier Transform-infrared, FTIR), nitrogen content and liposome size. Also, improvements in surface properties such as hydrophilicity and dyeability were investigated and confirmed by weight loss, tensile strength, roughness, scanning electron microscopy (SEM), carboxyl content, wrinkle recovery angle, K/S values and fastness properties. Several factors have been reported to influence the incorporating efficiency of Cat Ls, such as SA concentra- tion, particle size and the effect of Cat Ls on the different properties of finished PET fabrics and improvement in softener production and colour strength. Experimental Materials The 100% PET woven fabric (200 g/m 2 , warp 60 ends/cm and weft 22 picks/cm) was kindly supplied by Misr El- Mehalla Co. (Egypt). The fabric was scoured in a bath containing 2 g/l of non-ionic detergent (Hostapal CV; Hoechst, Egypt) solution at 70 °C for 45 min at a liquor © 2013 The Authors. Coloration Technology © 2013 Society of Dyers and Colourists, Color. Technol., 129,1–10 1 doi: 10.1111/cote.12024