Synthesis And Application Of A Novel Perfluoroalkyl-Containing Polycarboxylic Acid

The requirement placed on quality of textiles grows constantly. Serviceability properties, such as repellency to water and oil are increasingly becoming the focus of interest. The market place has shown a fast increase in demand for easy care, wrinkle-resistant cotton apparel.To provide the treated surface with a low critical surface tension, fluorochemicals are most abundantly used for their ability to lower the critical surface tension of the treated surface well below that of most liquid other than a fluorocarbon. At present, the most used fluorinated finishing agents are fluorinated acrylic polymers. Although they can attribute water and oil repellency to the textile substrates, they do not always show sufficient stability during use since the finishing agents used mostly constitute only surface layers and do not develop permanent chemical bonds to the textile substrate.The traditional durable press finishing agents of cotton fabrics contain formaldehyde or formaldehyde-related compound. They are effective and cost-efficient. However, the release of formaldehyde vapor during the subsequent storage and consumer use of finished cotton products has caused worldwide concern over their impact on human health. Polycarboxylic acids have been used in cotton textiles as an alternative in crease-resistant process.In the light of the above facts, we envisaged that a molecule,perfluorooctylated polycarboxylic acid, which contains both perfluoroalkyl chain and multi-carboxylic acid groups, should be a suitable finishing agent for fabrics with water-, oil-repellency and wrinkle resistance.The desired perfluorooctylated polycarboxylic acid was synthesized via alkylation of triethyl citrate with allyl bromide, in the presence of silver(I) oxide in n-hexane. The yield was 36%. The resulting compound was treated with perfluorooctyl iodide initiated with 2, 2'-azobis(2-methylpropionitrile) (AIBN) to give the addition product, which was then reduced with tri-n-butyltin hydride initiated with AIBN to afford perfluorooctylated tricarboxylate. The yields of two steps are 84.5% and 78.2% respectively. At last, the perfluorooctylated tricarboxylate was hydrolyzed to give perfluorooctylated polycarboxylic acid in 79.3% yield.The obtained perfluorooctylated polycarboxylic acid was applied to cotton fabrics by conventional pad-dry-cure process. The treated fabrics showed good oil repellent and moderate water repellent properties: the oil repellent rating and the water repellent score were 6 and 80 respectively. Even after 10 washing cycles, the repellent properties were kept at the same level. The finished fabrics also showed some the wrinkle-resistant properties, the dry wrinkle recovery angle was increased by 53° compared with untreated fabrics. The critical surface energy of the treated fabric surface was 20 + lmN/m. This multifunctional compound also showed good water solubility, which would be beneficial for the environmental protection.