Preparation And Surface Properties Of Environmentally Friendly Short Chain Perfluoroalkyl Fabric Water And Oil Repellent Finishing Agent

At present,the oil repellent finishing agents for fabrics are mainly organic polymers containing eight carbon perfluorinated chain segments(C₈F₁₃),which are easy to release the most difficult to degrade organic pollution perfluorooctanoic sulfonyl compounds（PFOS）or perfluorooctanoic acid compounds（PFOA）in large quantities,causing impact on human health and living environment.The newly developed fluorine free durable waterproof agent has excellent waterproof property and durable washing property,but it is not oil proof.The research and development of environment friendly,high performance short fluorocarbon chain fabric oil repellent is an important research topic in the field of ecological dyeing and finishing.Firstly,this paper synthesized short chain perfluoroalkyl hybrid emulsions with different compositions,the preparation of environment friendly short chain perfluoroalkyl fabric water repellent and oil repellent finishing agent and the surface property regulation of latex film were systematically studied,and the synergy between long alkyl crystalline side chains and short fluorine side chains-CF₃groups.Secondly,the structure of functional monomer segments was controlled by reversible addition-break chain transfer radical polymerization（RAFT）,and a core-shell block copolymer emulsion was prepared by modified inorganic nanoparticles to achieve the regulation of copolymer sequence structure,and the interaction between the latex particle composition,morphological structure,and surface morphology and properties of the latex film was established.Finally,the water and oil repellent finishing process of the fabric was optimized,and the structure and application properties of the fabric were analyzed to realize the water and oil repellent finishing of different substrates.The specific research content is as follows:（1）Preparation and properties of an environment friendly short chain perfluoroalkyl hybrid emulsionA series of fluorinated polyacrylate hybrid emulsions with short perfluoroalkyl side chains were prepared by the copolymerization of 2-（perfluorobutyl）ethyl acrylate（C₄F）and stearyl acrylate（SA）as functional monomers.When the mass ratio of C₄F:SA was 1:1,the surface free energy of the hybrid latex film was 17.79 m N/m.The latex film showed a two-phase structure of"sea"and"island",with a roughness of6.448nm and a high strength of crystalline zone.Elemental analysis showed that the content of F on the surface of the latex film was higher,reaching 18.74%.The results showed that SA and C₄F have a better synergy,the SA medium length base crystalline side chain can effectively limit the movement of short fluoride chain segments in C₄F,thereby improving the stability of the surface structure,greatly reducing the surface restructuring,promoting the accumulation of surface-CF₃clusters,and it also has better membrane and thermal stability.（2）Preparation and surface properties of environmentally friendly short chain perfluoroalkyl block copolymer latex based on RAFT emulsion without soapOn the basis of the above studies,the core-shell short chain perfluoroalkyl block copolymer emulsion was prepared by RAFT emulsion polymerization with amphiphilic large molecular RAFT agent instead of small molecular emulsifier with C₄F and SA（1:1）and nano silica as the main copolymers.When the total content of C₄F and SA（1:1）accounted for 60 wt%of the film forming monomer,and the content of modified Si O₂was 2 wt%of the total monomer,the surface free energy of the block copolymer emulsion decreased to 15.32 m N/m,the surface roughness of the block copolymer latex film increased to 6.997 nm,and the strength of the crystal zone of the latex film was high.Elemental analysis showed that the content of the F element on the surface of latex film increased to 24.61%.The lower surface free energy of the latex film was further confirmed.The results show that RAFT emulsion polymerization can regulate the sequence of block copolymers,and most functional chains（fluorinated side chains and crystalline side chains）preferentially accumulate on the latex film surface.Moreover,the addition of nanoparticles increased the surface roughness of the latex film,effectively expanded the fluorine content on the surface,and made the surface have a lower surface free energy.（3）Application of environmental protection short chain perfluoroalkyl block copolymer in water and oil repellent finishing of fabricsThe preparation of environment friendly short chain perfluoroalkyl block copolymer emulsion was finished on cotton fabric,and its technology was studied according to the static contact Angle of cotton fabric to water and oil.The experimental results show that when the concentration of fine emulsion was 80 g/L,dried at 80℃for 180 s,and baked at 150℃for 150 s,the contact angles of the fabric to water and oil are 152.5°and 142.4°,respectively,and the fabric has good water and oil repellents.After the physical properties of the finished cotton fabric were tested,the washable resistance,air permeability,breaking strength,wear resistance and wrinkle recovery performance were tested.The test results showed that the finished cotton fabric had little influence on its physical and mechanical properties,and could still meet the daily wear performance of the fabric.Then through the physical properties of the test,after washing resistance,air permeability,fracture strength,wear resistance and wrinkle recovery performance test,the test results show that the finished cotton fabric has little effect on its physical and mechanical properties,can still meet the daily fabric wear performance.In summary,in order to use low dose functional monomers（C₄F and SA）to prepare high performance finishing agents to replace long fluorocarbonic compounds,this study prepared an environmentally friendly short chain perfluoroalkyl hybrid emulsion with C₄F and SA functional monomers as systems,and investigated the synergistic interaction between the long alkyl crystalline side chain in SA and the amorphous short fluorine chain segment in C₄F.On this basis,the self-made RAFT reagent was used as emulsifier to prepare short-chain perfluoroalkyl block copolymer emulsion,and the effect of the amount of modified nano silica on the surface free energy of the short chain perfluoroalkyl block copolymer emulsion film was investigated,and the sequence structure of the copolymer was regulated.The core-shell type short chain perfluoroalkyl block copolymer emulsion was obtained,which was environmentally friendly,stable in storage and good in application.It can be used in cotton,polyester and polyester/cotton substrates.This study laid a theoretical foundation for the industrial application of environmental protection short chain perfluoroalkyl water and oil repellent.