The Research On The Surface Modification Of Aluminium By Plasma And The Surface Initiated-polymerization

Alumium in actual production applications were restricted in related fields due to the existence of many defects on the surface. Via Plasma technology, the material surface was initiated and the acrylic acid monomer was polymerized which can achieve surface modification, such as: hydrophilic property, absorption, etc. so as to achieve the purpose of surface functionalization. It was a great significance on practice.In this study, the aluminum was used as the base material, activated by the sodium hydroxide, and treated by the radio frequency plasma which used Ar as the treated gas. Then there were effective groups with active free radicals on the aluminum surface. After the radicals'concentration has been measured by the DPPH concentration method, the optimum conditions on the modification of the surface by Ar plasma can be determined. The optimum conditions by Ar plasma treatment were: the reaction pressure of 80Pa, Radio Frequency(RF) power of 150W, the time treated the aluminum of 3min and the exposure time in the air of 3min. Under the deal, the quality of aluminum increased, surface-initiated polymerization was the best, and do not affect the nature of the aluminum body.After the optimum conditions on the treatment by Ar plasma were determined, the method of the solution graft polymerization was used. The treated aluminum was put into the solution of sodium acrylate monomer to polymerize. The aluminum surface was chacterized by the methods of Fourier Transform infrared spectroscopy(FTIR),Atomic Force Microscope(AFM),X-ray Photoelectron Spectroscopy(XPS) and so on. The graft rate can be measured by the mass change of the aluminum, thus, the optimums conditions on the polymerization can be determined. the optimum conditions of the sodium acrylate polymerization is that the reaction pH value of 6.8-7, the reaction temperature of 70℃and the reaction time of 4h.。The result shows that under the optimums conditions during the polymerization process, the aluminum surface can polymerize sodium acrylate monomer by successfully initiation, graft a film of the sodium polyacrylate, and the graft rate reached to 10%.The change of the hydrophilicity was compared by the contact angle measurement. The result shows that the aluminum with the film of the sodium polyacrylate can improve the hydrophobicity. The absorption rate of the aluminum surface was mearsured by the method of the coomassie brilliant blue g 250. the surface topography of the aluminum after absorpting the protein was observed by the scanning electron microscope (SEM). The result shows: the absorption rate of the aluminum with the sodium polyacrylate film reached to 52.3%, which was evidently higher than the normal aluminum and has good absorption. The study on the properties proves the feasibility of the surface modification and surface-initiated polymerization by plasma to realize the material functionalization.