Synthesis And Application Of Novel Fluoropolymer Textile Finishing Agents

The research of fluoropolymer textile finishing agent is an important branch of organofluorine chemistry because fluoropolymer textile finishing agents provide textile with optimum performance in terms of both water- and oil- repellency without impairing the textile's permeability to air, comfort ability, color or hand feel. They have been becoming the leading finishing agents for achieving water- and oil- proof. In this dissertation, several classes of novel fluoropolymer textile finishing agents were designed, synthesized, characterized and evaluated. The whole dissertation consists of the following four parts.Part 1: Fluorooxetane monomer 34FOx containing oleophobic/hydrophobic groups and oxetane monomer EtOx containing hydrophilic groups were designed and synthesized. Polyoxetanes P(34FOx:EtOx) were synthesized through cationic ring opening polymerization by using 34FOx and EtOx as starting materials. Then polyurethane PU3 which can form oleophobic/hydrophobic- hydrophilic smart surface was prepared by employing isophorone diisocyanate (IPDI) and 1,4-butanediol (BD) as the hard segments and P(34FOx:EtOx-1:1) as the soft segments. The static contact angle for olefin liquid on PU3 treated glass and cotton fabric reached to 85°and 119°, respectively. The initial maximum static water contact angle was 108°when the water was dropped on the PU3 treated glass plate which indicated that the polyurethane surface was hydrophobic, however, a significant decrease of WCA from 108°to 25°within 25 minutes was observed which indicated the surface of PU3 coating has switched from hydrophobic to hydrophilic.Part 2: Fluorooxetane 6FOx containing short fluoroalkyl groups and 3,3-bisbromomethyloxetane BrOx were designed and synthesized. Starting from these two monomers, Polyoxetanes P(6FOx:BrOx) were synthesized through cationic ring opening polymerization. Then, polyurethanes FBr-PU bearing hydrophobic groups (-CF₃) and reactive groups (-Br) were prepared by employing isophorone diisocyanate (IPDI) and 1,4-butanediol (BD) as the hard segments and P(6FOx:BrOx) as the soft segments. The fabrics treated with FBr-PU showed good hydrophobicity (WCA =133°) and could be further modified via substitution reaction of the reactive bromomethyl groups.In addition, monomer FSOx was also designed and synthesized by using perfluorobutyl sulfuryl fluoride as starting material. The hydantoin-oxetane monomer HyBrOx was synthesized via N-alkylation and Williamson etherification reaction with 5,5-dimethylhydantoin as starting material. Polyurethane FHy-PU would be prepared from copolymerization by using copolymer of FSOx and HyBrOx as soft segments, and isophorone diisocyanate (IPDI) and 1,4-butanediol (BD) as the hard segments. FHy-PU would impart unique properties to the fabrics, such as water-repellency, breathability, antibiosis and easy decontamination. However, in this dissertation, we only finished the synthesis of monomers FSOx, FBrOx and HyBrOx due to time limitation, and further intensive efforts would be made to accomplish the following polymerizations.Part 3: A novel waterborne polyurethane WFPU containing short fluoroalkyl groups was designed and synthesized by using water as dispersive medium, which had advantages in fire safety, innocuity, environmental pollution, energy conservation and workability etc. WFPU with short perfluoroalkyl group (-CF₃) could avoid the environmental and bioaccumulative problems caused by long perfluoroalkyl groups. It was an environmental benign textile friendly finishing agent. The contact angle of water for WFPU treated glass reached to 111°, which indicated good water repellency.Part 4: The lowering of surface energy through chemical modification can enhance the hydrophobicity/oleophobicity of a surface. Previous studies have been focused on the use of long perfluoroalkyl chains C_nF_2n+1(n≥8) to lower the surface energy. However, there are some evidences concerning possible persistence, bioaccumulation, and/or toxicity of these types of fiuorochemicals in the environment. The new strategies are concerning how to synthesize suitable chemicals that have excellent water and oil repellency without the need for long perfluoroalkyl groups. Fluorinated acrylates 3a-d were designed and synthesized. Then, fluorinated polyacrylates 4a-d were prepared by using emulsion polymerization. Copolymers 4a-d were used for finishing of cotton fabrics by a pad-dry-cure process. Polymers 4b and 4c containing partially fluorinated alkyl groups (-CH2CF2-) showed comparable water and oil repellent properties to conventional polymer 4a which containing long perfluoroalkyl groups. The contact angles of n-tetradecane for 4b and 4c treated fabrics were reached to 116°and oil repellency rating was six and five, respectively. The contact angles of water for 4b and 4c treated fabrics was 140°and 138°, respectively, and water repellency rating were six. Polymer 4d containing the same length carbon chain with C4F9- group provided the treated cotton fabrics with water repellency rating at five but no oil repellency. Thus, polyacrylates containing vinylidene fluoride units showed promising value as the alternatives to the currently used water and oil repellent agents which contain long perfluorocarbon chains.