The Synthesis Of Novel Fluorinated Acrylate Co-Polymers And Their Applications On Cotton Fabrics

Fluorinated coatings are the most important class of water- and oil-repellent finishing agents for textiles due to their optimum performance in lowering the surface free energy and improving both hydrophobicity and oleophobicity. Most of them are containing long perfluoroalkyl chains (C_nF_2n+1, n>6), the main chain of the polymers and other functions. However the long perfluoroalkyl chains have been facing problems such as persistence, bioaccumulation, and/or toxicity in the environment, and some of them have been banned from the market. The use of perfluorooctyl-containing surfactants such as perfluorooctane sulfonates (PFOS) and perfluorooctanoic acid (PFOA) have been restricted in the international community. So it is important to find the alternatives to replace the present long perfluoroalkyl-contained fluorocarbons. Accordingly, in this paper, we designed the fluorinated acrylate monomers containing perfluorohexyl which is friendly to the environment. On the other hand, in order to reach better water- and oil-repellency, we have to increase the rigidity of the branched-chain to make sure that the short-chain fluorocarbon gathered in the outer layer of polymer to get lower surface energy. As a result, in this paper, we designed fluorinated acrylate monomers: 1a, 1b, 2, which contained a benzene ring. At first, 4-allylanisole was treated with perfluorohexyl iodide under the initiation of sodium hydrosulfite. The radical addition was proceeded smoothly to afford 4-(1'-perfluorohexyl-2'-iodo)propyl anisole 5. The reduction of iodo group in 5 was accomplished by treatment with n-Bu₃SnH/AIBN system to give 4-(-1'-perfluorohexyl)propyl anisole 4 in 83% yield respectively. The methyl group in 4 was then removed by treated with BBr₃ to give 4-(1-perfluorohexyl)propyl phenol 3, which was then esterified with acrylic chloride or (meth)acryloyl chloride to provide fluorinated acrylate monomer 1a or 1b respectively.Toluene diisocyanate (TDI) was treated with 1H,1H,2H,2H-perf!uorooctanol first when diutyl tinlaurate (DBTDL) was used as the catalyst. The addition reaction was proceeded smoothly to give a monoisocyanate which was then treated with 2-hydroxylethyl acrylate (HEA) to afford the target monomer 2 in 85% yield.The fluorinated acrylate monomers 1a, 1b, 2 were co-polymerized with octadecyl acrylate and 2-ethoxyl acrylate by emulsion polymerization to give co-polymers PFA1, PFA2 and PFA3. Nonionic surfactant (OP-10)and sodium laury sulfate (SDS) were used as the emulsifying agents in order to get stable emulsions. The partical size distribution and morphology of the emulsions were measured by Malvern 2002. The structures of PFA1, PFA2 and PFA3 were characterized by FT-IR, the thermal stability was measured by TG.The PFA1, PFA2 and PFA3 were diluted with water to form 2 wt%, 4wt%, 8wt% emulsions, and these emulsions were applied on cotton fabrics by pad-dry-cure process. According to the water- and oil-repellency measurement, we found that the 8wt% emulsions reached the best effect. Under this concentration, the water-repellency of both PFA1 and PFA3 reached grade 6 and scored 80. The water-repellency of PFA2 was grade 5 and scored 70. On the other hand, the oil-repellency of PFA3 reached grade 3 while PFA1 and PFA2 showed no obvious oil-repellent effect. In the contact-angle test, the contact angle of treated fabrics for water was measured as 142°for PFA1, 136°for PFA2 and 139°for PFA3. The contact angle of cotton fabrics treated with PFA1 and PFA2 for paraffin oil reached 106°and 104°respectively. The contact angle of treated fabrics treated with PFA3 for n-hexadecane was measured as 114°. As the result, PFA3 with an amino ester group possessed better water- and oil-repellent properties.