Surface Grafting Is Used For The Study Of Hydrophilic/hydrophobic Modification On The Surface Of Silicon Wafers

Polymer is a kind of good material for surface functionalization and modification of silicon wafers.By means of polymer chemical bonding,good contact and stable bonding between silicon wafer matrix and modified molecules can be maintained.Surface grafting method is an effective modification method for functional modification of substrate surface.The surface grafting method is used to form a functional polymer layer on the surface of the substrate,which opens up a broader application prospect for the surface modification of silicon wafers.Firstly,functional silane coupling agent KH570 was used to modify the silicon wafer,and the preliminary modified silicon wafer Si-KH570 was obtained.The silicon wafers with certain hydrophilic properties were prepared by grafting acrylamide(AM)on the surface of silicon wafer Si-KH570 by free radical polymerization.In order to further improve the hydrophilicity of silicon wafers,methacryloylethylsulfobetaine(SBMA)with good hydrophilic function was grafted on the surface of silicon wafers Si-KH570 by free radical polymerization.The surface of silicon wafer was modified by using trifluoroethylmethacrylate(TFEMA)monomer containing hydrophobic functional group to obtain the silicon wafer with hydrophobic property.The chemical structure,elemental composition,roughness and wettability of the sample surface before and after modification were investigated in detail.The effects of different monomer concentrations on the surface wettability and grafting rate of silicon wafers were studied in detail.The study found that when the AM concentration was 3.5wt%,the grafting rate reached a maximum of 0.61%,the surface roughness Ra of the modified silicon wafer increased from 1.15 nm to 5.04 nm,the contact angle decreased from 70.32° to19.3°,and the hydrophilicity was effectively improved.When the SBMA concentration was 2.5wt %,the grafting rate reached the maximum value of 0.6%,the surface roughness Ra of modified silicon wafer increased from 0.338 nm to 11 nm,and the contact angle decreased from 70.32° to 8.89°.Compared with AM modified silicon wafer,SBMA modified silicon wafer has better hydrophilic energy.When TFEMA concentration was 3wt%,the grafting rate reached the maximum value of 0.52%.After modification,the surface roughness Ra of silicon wafers increased from 1.15 nm to 1.66 nm,the contact angle increased from 70.32° to 102.9°,and the surface of silicon wafers changed from hydrophilic to hydrophobic.