RESUMEN
Controlling the surface properties of solid polymers is important for practical applications. We here succeeded in controlling the surface segregation of polymers to display carboxy groups on an outermost surface, which allowed the covalent immobilization of functional molecules via the carboxy groups on a substrate surface. Random methacrylate-based copolymers containing carboxy groups, which were protected with perfluoroacyl (Rf) groups, were dip-coated on acrylic substrate surfaces. X-ray photoelectron spectroscopy and contact-angle measurements revealed that the Rf groups were segregated to the outermost surface of the dip-coated substrates. The Rf groups were removed by hydrolysis of the Rf esters in the copolymers, resulting in the display of carboxy groups on the surface. The quantification of carboxy groups on a surface revealed that the carboxy groups were reactive to a water-soluble solute in an aqueous solution. The surface segregation was affected by the molecular structure of the copolymer used for dip-coating.
RESUMEN
We propose a rational strategy to control the surface segregation of an amphiphilic copolymer in its dip-coating with a low-molecular-weight surfactant. We synthesized a water-insoluble methacrylate-based copolymer containing oligo(ethylene glycol) (OEG) (copolymer 1) and a perfluoroalkylated surfactant (surfactant 1) containing OEG. The dip-coating of copolymer 1 with surfactant 1 resulted in the segregation of surfactant 1 on the top surface of the dip-coated layer due to the high hydrophobicity of its perfluoroalkyl group. OEG moieties of surfactant 1 were accompanied by those of copolymer 1 in its segregation, allowing the OEG moieties of copolymer 1 to be located just below the top surface of the dip-coated layer. The removal of surfactant 1 produced the surface covered by the OEG moieties of the copolymer that exhibited antifouling properties. Using this strategy, we also succeeded in the introduction of carboxy groups on the dip-coated surface and demonstrated that the carboxy groups were available for the immobilization of functional molecules on the surface.