Studies Of Waterborne Polyurethane Modified With Silicone

Waterborne polyurethane(WPU)performs not as good as traditional PU in mechanical properties,water resistance and hydrophobicity because of the characteristics of its structure.In this work,we synthesized a polysiloxane microsphere and amphiphilic polymer-Ag nanocomposite microsphere with stabilization good dispersity and controllable morphology through the mini-emulsion polymerization.The microsphere aboved,Polydimethylsiloxane(PDMS)and aminosiloxane(KH550)were incorporated into WPU for modification so a series of dispersions and nanocomposite dispersions were obtained,and the properties of WPU were studied.(1)The polysiloxane microsphere was synthesized by mini-emulsion polymerization with ?-Methacryloxypropyltrimethoxysilane(MPS),then the polysiloxane microsphere was incorporated into WPU which was modified by polydimethysiloxane(PDMS),its nanocomposite dispersions and films were obtained.The influence of PDMS,polysiloxane microsphere content,pH and curing temperature to the dispersion and film properties were discussed.The result showed that when PDMS content was 8%,and polysiloxane microsphere content was 10%,the nanocomposite films had a good tensile strength(26.1 MPa),water resistance(water absorption was 18.5%)and surface hydrophobic(water contact angle was 100.3°).The performance of the film is improved significantly.The SEM showed that when polysiloxane microsphere content was more than 10%,it agglomerated and dispersed poorly.In addition,when the pH of the emulsion was 12 and the curing temperature was 110 °C,the comprehensive performance of the film was further improved.(2)The polyurethane prepolymer was terminated by ?-aminopropyl triethoxysilane(KH550),then polysiloxane microsphere was incorporated into PU and its nanocomposite dispersions and films were obtained.The influence of KH550 content and polysiloxane microsphere content to the dispersion and film properties were discussed.Results showed that when KH550 content was 5%,the film had good mechanical water resistance and surface hydrophobic.With the introduction of the polysiloxane microsphere and KH550,microspheres did not agglomerate and were dispersed in the matrix as shown in SEM,which was beneficial to the improvement of films performance.When the content of polysiloxane microspheres was 4%,the tensile strength(47.0 MPa),water resistance(water absorption was 3.7%)and surface hydrophobic(water contact angle was 103.3°)of WPU film reached an optimal state.(3)The polysiloxane microsphere was modified by different portions of KH550 and its surface immobilized nano silver particles through complexing action,polysiloxane-Ag microspheres were obtained.TEM showed that when KH550 content was 5% and AgNO3 concentration was 0.4 mol/L,the polysiloxane microsphere shows a good morphology,dispersibility and the nano silver particles could adhere onto the surface of the microspheres homogeneously.The growth of Escherichia coli(Gram-negative bacteria)and staphylococcus aureus(Gram-positive bacteria)was significantly inhibited by the polysiloxane microsphere solution,which proved that polysiloxane-Ag microspheres had broad spectrum antibacterial properties.The polysiloxane-Ag microsphere was incorporated into the WPU terminated by KH550 so the WPU-Ag composite dispersions and films were obtained.The research suggests that the nanocomposite films have tensile strength,water resistance and surface hydrophobic improved in comparison with those unmodified.The growth of Escherichia coli(Gram-negative bacteria)and staphylococcus aureus(Gram-positive bacteria)was significantly inhibited by the WPU-Ag composite film,it thus proved that WPU-Ag composite films have broad spectrum antibacterial properties.