Preparation Of Antibacterial Hybrid SiO₂ Nanoparticles And Its Modification On Polymers

In this paper,a series of functional antibacterial nanoparticles were prepared by simple and efficient method,and then hybrid nanoparticles were mixed with polyurethane and polyvinyl alcohol solutions to form the composite films.The antibacterial properties of hybrid nanoparticles and composite films were systematically studied.The research contents were as follows:（1）A series of reactive QACs with different chain lengths were prepared by inexpensive tertiary amine silane coupling agent,which were covalently grafted onto the surface of SiO₂nanoparticles in one step via a modified St?ber method.The structure and appearance of hybrid SiO₂ nanoparticles were studied by FTIR,TEM and TGA.The antibacterial activity of hybrid SiO₂ nanoparticles was evaluated by shake flask method.The results showed that the hybrid SiO₂ nanoparticles have a relatively regular spherical shape,a high quaternary ammonium content on the surface,good dispersibility and hydrophobicity.Antibacterial test results indicated that the hybrid SiO₂ nanoparticles have excellent antibacterial activity compared with pure SiO₂ nanoparticles,and can completely killed Escherichia coli and Staphylococcus epidermidis in 20 min.Moreover,the hybrid SiO₂ nanoparticles were contact antibacterial material,no antibacterial substance leaching.（2）The polyurethane composite films with excellent antimicrobial properties were obtained from a mixture of a polyurethane acrylate prepolymer and hybrid SiO₂ nanoparticles via UV curing.The effects of hybrid SiO₂ nanoparticles with different particle size and alkyl chain length on the properties of polyurethane composite films were studied.The test results showed that the hybrid SiO₂ nanoparticles were enriched on the surface of the films.Adding a small amount（5 wt%） of hybrid SiO₂ nanoparticles could endow the films with good antibacterial properties.As the particle size of the hybrid SiO₂ nanoparticles decreases and the length of the QAC alkyl chain increases,the antibacterial properties of the composite films were further improved,achieving an antibacterial rate of 100%.After the films were accelerated and aged for 10 days,the antibacterial property was hardly decreased,indicated that the composite films have excellent antibacterial durability and stability.The test of the inhibition zone showed that the composite films were contact antibacterial material,no antibacterial substance leaching,which were safer and more efficient.（3）Hybrid SiO₂ nanoparticles F-Q-12 were prepared by bonding bactericidal QAC-12and hydrophobic fluorosilane AC-FAS to the surface of silica nanoparticles.Firstly,the chemical structure,micromorphology and hydrophilicity of F-Q-12 were studied,and the PVA composite films with excellent antimicrobial properties were obtained from a mixture of PVA solution and hybrid SiO₂ nanoparticles via natural dry.The effect of the addition amount of F-Q-12 on the properties of PVA composite film was studied.The results showed that the F-Q-12 nanoparticles are more hydrophobic and the contact angle reaches 138.3°.Due to the introduction of a perfluoroalkyl chain,F-Q-12 had a lower surface energy and was more easily enriched on the surface of the films.Adding 3 wt%of F-Q-12 could endow the films with good hydrophobicity and antibacterial property,the angle can reach 96.6°,and the antibacterial rate against Escherichia coli and Staphylococcus epidermidis reaches 100%,indicated that the synergistic effect of hydrophobic surface and antibacterial could further improved the antibacterial property of the composite films.The test of the inhibition zone showed that the composite films were contact antibacterial material,no antibacterial substance leaching.Moreover,the addition of F-Q-12 also improved the mechanical properties and thermal stability of the film.The tensile strength of PVA/F-Q-12（3%）reached 65.2 MPa and the elongation at break was 28.1%.