Surface Modification Of Polymethyl Methacrylate By Plasma Treatment And Its Properties Of Anti-bacteria And Resistant To Protein Adsorption

Biomedical composite material is a kind of biomedical material which is composed of matrix and reinforcing material.Due to its high mechanical strength and chemical stability,biomaterial can be used for tissue repair and organ replacement.Polymethyl methacrylate(PMMA)is a common matrix material for medical composites because of its low tissue rejection and biological aging resistance.With the development of medical composite materials,higher requirements are put forward for long-term use,and for reducing bacterial infection and local inflammation.Plasma technology has a low damage effect for surface modification,and has remarkable effect on the enhancement of surface properties,that led to increasing interest in the modification of medical polymer materials.Plasma modification can improve the hydrophilic of materials surface,enhance the bonding strength between components,and extend use-life of the composites.Besides,decrease in surface protein adsorption,reduction in the chance of bacterial reproduction is another advantage of plasma technology.In this thesis work,low pressure radio frequency capactively coupled plasma is used for surface modification,which is carried out under different working atmosphere.The influence of plasma power on surface properties of hydrophilic,antibacterial and antiprotein adsorption were investigated;Physical and chemical interactions are studied specifically.The main contents and conclusions are as follows:(1)The effect of processing time and discharge power on the surface properties of PMMA was analyzed.Results indicate that,air plasma modification improve hydrophilic,antibacterial and antiprotein adsorption properties of materials surface.When the plasma processing time is less than 100 s,surface hydrophilicity increased with the increase of processing time,and then tended to be stable.When the discharge power is less than 100 W,surface hydrophilicity can be enhanced obviously by increasing discharge power.If plasma power continues to increase,the modification effect will no longer enhanced.When surface hydrophilicity is accompanied by the improvement of the antibacterial and antiprotein adsorption properties.(2)To investigate the role of nitrogen and oxygen in air plasma,the influence on surface properties and the main factors of plasma modification with Ar,N2 and O2 gas is studied.The results show that surface hydrophilic and anti-protein properties are improved by plasma treatment.The etching effect occupies the dominant position in Ar plasma,while grafting effect are dominant in N2 and O2 plasma.When the plasma power is low,increasing power can greatly improve the surface hydrophilic of PMMA,and the higher surface hydrophilic will result in the higher anti-protein properties.(3)In order to further improve the properties of antibacterial and antiprotein adsorption on PMMA surface,the effects of O2 and CF4 plasma on the surface properties are studied.The results discover that O2/CF4 plasma has both the advantages of O2 and CF4 plasma:the enhancement of surface hydrophilic by O2 plasma,and the improving of antibacterial and antiprotein adsorption properties by CF4 plasma.After O2/CF4 plasma treatment,the surface of PMMA shows hydrophilicity,which is not similar to the hydrophobic surface treated with CF4 plasma.At the same time,the antibacterial and antiprotein adsorption performance of PMMA surface is better than O2 plasma treated one.