Research On Antibacterial Technology Based On Laser Induced Backward Transfer

The outbreak of the COVID-19 has brought to light the dangers posed by microbial infections.Bacteria are one of the microorganisms that can easily cause bacterial infections in humans when they adhere to the surface of everyday objects and form biofilms.The availability of antimicrobial surfaces is therefore essential for such items.However,conventional antimicrobial surface technology is notorious for its harsh processing environment,low processing efficiency and environmental pollution.To address these shortcomings,this study developed a method for preparing antimicrobial coatings.An antimicrobial coating has been prepared on the surface of mobile phone cases based on laser-induced backward transfer technology in order to achieve antimicrobial properties in mobile phone cases.The main work accomplished in this thesis is as follows:(1)A silver-copper coatings were prepared on the surface of mobile phone cases using silver-copper films of different mass ratios and thicknesses as transfer materials.Firstly,a silver-copper composite coating was deposited on the surface of the mobile phone case using laser-induced backward transfer technology with a thin silver-copper film as the transfer material and a transparent mobile phone protective case as the receiving substrate.The effect of laser processing power in the range of 5W-15 W on the coating morphology and element distribution was analysed.At a laser power of 9W and a scanning speed of600mm/s,the film was completely transferred to the surface of the phone case and a large number of silver-copper particles were deposited on the surface of the phone case forming a silver-copper composite coating.The antibacterial effect of the coating was assessed using the dilution coating plate method and the effect of different silver to copper mass ratios on the antibacterial effect of the coating was investigated.The results show that when the silver-copper content is limited and the silver-copper mass ratio is 3:1,the coating achieves an antibacterial rate of over 99.99% against Escherichia coli and Staphylococcus aureus.Some areas of the coating prepared using the silver-copper film as a transfer material are subject to peeling,which affects the antimicrobial effect.Therefore,there are still shortcomings in using silver copper thin films as transfer materials.(2)A silver-copper coating was prepared on the surface of a mobile phone case using a bulk material with a silver copper mass ratio of 3:1 as a transfer material.Laser-induced backward transfer technology is used to induce the deposition of silver-copper material from the silver-copper body material to the surface of the phone case in the form of particles.The effect of laser power in the range of 8W-18 W on coating morphology,element distribution and transmittance was analysed.The results show that as the laser power increases,the particle density on the surface of the phone case increases,the mass share of silver and copper elements on the surface of the phone case also increases,and the transmittance gradually decreases.The antibacterial effect of the coating was evaluated and the silver-copper coating achieved over 99.99% against both Escherichia coli and Staphylococcus aureus at a laser power of 16 W.The adhesion of the coating was tested using the tape and the antibacterial rate of the coating did not change before and after the test,proving that the coating adheres well to the surface of the phone case.In summary,this study proposes a method for the preparation of antimicrobial surfaces based on laser induced backward transfer.The silver-copper material was used as a transfer object and a silver-copper coating was deposited on the surface of the mobile phone case using laser processing technology to achieve a high antibacterial rate coating on the surface of the case.The influence of laser parameters on the antibacterial effect of the coating was analyzed,and the optimal processing parameters were obtained.This provides a new idea for the preparation of antibacterial surfaces of organic materials at low cost,large area,and common environments.