Preparation And Properties Of Fluorine-containing Polyacrylate Emulsions Modified With Polyurethane/PDMS

The fluorine-containing polyacrylate compounds can be used as textile finishing agents to treat fibers and render fibers the ability of waterproof and antifouling at low applied amount.In some cases,fluorinated polyacrylates have the drawbacks of poor adhesion,high cost and poor dispersibility,and the use of organic solvents in production process,limiting their widely applications to certain extent.Especially in the case for the emulsion polymerization of fluorine-containing polyacrylates,where emulsifiers have to be used,leading to some problems affecting the performance fluorinated polyacrylates.In this thesis,the emulsions of waterborne polyurethane modified fluorinated polyacrylates and waterborne polyurethane/polydimethylsilicone modified fluorinated polyacrylates were prepared,and their properties were investigated,in order to obtain fluorine-containing polyacrylates with excellent performance as textile finishing agents.1.Waterborne polyurethane emulsions were synthesized by polymerization of diisocyanate(MDI,HDI,IPDI,TDI)and polyether diols(PPG,PEG,PTMG),followed by chain extension with N-methyldiethanolamine,terminal capping with hydroxyethyl acrylate,neutralization with acetic acid.IR was used to characterize the structure of polymers;DLS was used to characterize particle distribution and surface charge.Coatings on cotton cloth surface were prepared and characterized with contact angle wettability.Through comparative analysis of emulsion stability and coating anti-washing ability,the experimental conditions for preparing polyurethane emulsions were optimized.The results showed that when MDI and PTMG were used,the obtained cationic waterborne polyurethane emulsion had no agglutination occurrence,and showed high emulsion stability.The emulsion had a particle size of ca.116.8 nm and a particle distribution index(PDI)of 0.179,exhibiting their uniform distribution.The surface charge of emulsion particles had a Zeta potential of+46.7 mV.The coating on fibers had a contact angle of 138.6°.Thermogravimetric analysis indicated that the starting decomposition temperature was 2500C.2.The obtained polyurethane emulsion as a seed emulsion was added an acrylate(perfluorohexylethyl acrylate,methyl methacrylate,stearyl methacrylate,etc.)and an initiator V50,and the emulsion polymerization was conducted under argon to obtain a polyurethane modified fluorinated polyacrylate emulsion.DLS and TEM were used to characterize particle distribution and surface charge of the emulsion;IR and thermal analysis were used to characterized the structures of the polymers and thermal stability.Coatings on cotton cloth surface were prepared and characterized with SEM.Contact angle measurement and water leaching test were used to characterize its wettability and water resistance.The results show that the emulsion has excellent emulsion stability in which core/shell emulsion particles are formed with a mean size of ca.164.1 nm and a PDI of 0.216,exhibiting their uniform distribution.Thermogravimetric analysis indicates a starting decomposition temperature of 300?,meaning the good thermal stability.SEM tests show that the coating on the surface of the fabric has a layer of distributed particles,leading to a higher surface roughness and hydrophobic property for the fabric.The coating on fibers using a diluted emulsion of 1%concentration shows a contact angle of 138.6°.Water leaching test indicates that the coating of the fluorinated polyacrylate emulsion as fabric finishing agent has a good anti-washing resistance.3.The obtained polyurethane emulsion as a seed emulsion was added acrylates(perfluorohexylethyl acrylate,methyl methacrylate,stearyl methacrylate,etc.),vinylpolydimethylsilicone and initiator V50,and the emulsion polymerization was carried out under argon to obtain a polyurethane/polydimethylsiloxane modified fluorinated polyacrylate composite emulsion.Similar characterizations were performed as above.The results show that the emulsion has excellent emulsion stability in which core/shell emulsion particles are formed with a mean size of ca.163.9 nm and a PDI of 0.160,exhibiting their uniform distribution.Thermogravimetric analysis indicates a starting decomposition temperature of 300?,meaning the good thermal stability.SEM tests show that the coating on the fiber surface has a smooth coating layer.When the emulsions with 0.3%and 1%concentrations were used,both the fabric surfaces show contact angles higher than 175°,demonstrating excellent hydrophobicity.Water leaching test indicates that the coating of the fluorinated polyacrylate emulsion as fabric finishing agent has a good anti-washing resistance.Through the comparison of the performances of the two modified emulsions,it can be seen that the fluorine-containing polyacrylate emulsions modified with polyurethane/polydimethylsiloxane are able to achieve excellent hydrophobicity even a lower concentration of the emulsion is used.Latex particles in this emulsion have uniform dispersion,which is beneficial to improve the emulsion stability and the film-forming ability.The latter is of primary importance to form completely coating membrane on the fiber surface and achieve excellent anti-washing effect.