Reusable surface presenting amino groups using a degradable copolymer Fuga Hoshino, Sarina Yoshida, Kenta Morita and Tatsuo Maruyama Graduate School of Engineering, Kobe University, Japan A surface presenting amino groups is valuable because it can be used as a biosensor and a catalytic surface by immobilizing DNA, enzymes or ligands. In our previous study, we succeeded in presenting amino groups on the surface of a plastic substrate by dip-coating with a functional polymer. 1 However, once used, a substrate must be disposed of. In this study, we attempted to develop a reusable plastic surface presenting amino groups. We introduced a degradable copolymer with amino groups onto a surface of a plastic substrate using the simple dip- coating method. We examined the reusability of the functionalized surface through the surface degradation. We synthesized poly(CL-r-(Boc)OC-C6N), a copolymer with ester bonds in the main chain backbone and amino groups protected by Boc groups in the side chain. The size exclusion chromatography (SEC) analysis revealed that poly(CL-r-(Boc)OC-C6N) had Mn = 5.1×103, Mw/Mn = 1.77. A poly(CL-r-(Boc)OC-C6N) coating film was prepared on a PET substrate by the dip-coating method. The amino groups presented on a surface of a PET substrate were prepared by deprotecting the Boc groups by immersing the dip-coated substrate in 4 M HCl aq. To modify the substrate surface with perfluoroalkyl groups, a fluorinating compound, Rf8-COCl, which had a perfluoroalkyl group, was reacted with amino groups on the surface. XPS measurements observed a fluorine peak (F1s) on the modified surface, indicating that the fluorine modification was successfully achieved by the conjugation of perfluoroalkyl groups with the amino groups on the surface. The reusability of the surface of the PET substrate presenting amino groups was investigated using the fluorine- modified surface. The surface was degraded using 1 M NaOH aq. to remove the fluorine-modified surface layer. In the XPS measurements, the F1s peak observed on the fluorine-modified surface disappeared after the degradation. The results indicated that the fluorine-modified outermost layer was removed by the degradation. The substrate surface after the degradation was modified again with Rf8-COCl. The F1s peak was again observed on the surface of the re-fluorinated substrate by XPS measurements. The results demonstrated that the surface of the PET substrate presenting amino groups was again modified with perfluoroalkyl groups. These above results indicated that the surface of the PET substrate presenting amino groups was renewed by through the degradation of the coated polymers and reused for the surface functionalization. References 1. A Shimomura, et al ., Langmuir, 2013, 29 , 932-938
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