ИСТИНА

Due to its unique physical properties supercritical carbon dioxide has a great potential as a medium for modifying porous materials. Indeed, it is a cheap, non-toxic, non-flammable fluid with high diffusivity, low viscosity and no surface tension driven effects. Recently, DyeCoo Company has demonstrated that it is possible to use supercritical (sc) CO2 as a medium for textile dyeing process. Our extensive experience in sc CO2 research1–4 allowed us to develop a method for durable water repellent (DWR) application on various textiles via sc CO2 deposition. Modern DWRs are usually applied by immersing fabric in a bath with hydrophobic agent dissolved or suspended in a liquid solvent (usually water). The necessity to use liquid leads to high energy consumption of such a process at drying stage and waste-water problem. Moreover, surface tension of a liquid solvent causes hydrophobic agent to agglomerate when the solvent is drying. Such a non-uniform coating wears off rather fast making “durable water repellents” not really durable. In our approach we deposit hydrophobic polymers from solutions in sc CO2. A roll of fabric is inserted in the reactor with some amount of hydrophobic polymer. The reactor is then sealed, filled with liquid CO2 and heated above CO2 critical temperature (31oC). After the exposure reactor is decompressed slowly. On the decompression stage of the process polymer loses its solubility as the solution transforms from supercritical to gas phase and forms thin DWR coating on the fabric. Since sc CO2 does not have surface tension the resulted coating is formed uniformly on every individual fiber making DWRs with exceptional properties. No liquid is used in the process making it completely waste-free and environmentally friendly. Fluorinated acrylic polymers, the most widely used ones for water-repellent finishing, are readily soluble in CO2 even in liquid state. In the present work we have studied the morphology and performance of thin films of polyperfluoroalkyl acrylates with different length of fluorinated side chains (C6-C8) deposited from sc CO2 on nylon fabrics. Water contact angle dynamics, water spray test (ISO 4920) and hydrocarbon resistance test (ISO 14419) performance have been measured before and after multiple home laundry cycles. Promising results are achieved even at low polymer loadings (1-2 wt. %). 1. M. O. Gallyamov, R. A. Vinokur, L. N. Nikitin, E. E. Said-Galiyev, A. R. Khokhlov, I. V. Yaminsky, and K. Schaumburg, Langmuir, 18, 6928–6934 (2002). 2. I. V. Elmanovich, M. S. Kondratenko, D. O. Kolomytkin, M. O. Gallyamov, and A. R. Khokhlov, Int. J. Hydrogen Energy, 38, 10592–10601 (2013). 3. D. O. Kolomytkin, I. V. Elmanovich, S. S. Abramchuk, L. A. Tsarkova, D. Pospiech, M. Möller, M. O. Gallyamov, and A. R. Khokhlov, Eur. Polym. J., 71, 73–84 (2015). 4. T. E. Grigor’ev, E. E. Said-Galiev, A. Y. Nikolaev, M. S. Kondratenko, I. V. Elmanovich, M. O. Gallyamov, and A. R. Khokhlov, Nanotechnologies Russ., 6, 311–322 (2011).