Preparation of three-dimensional polymeric structures using gas bubbles as templates

Three-dimensional polymeric structures supported on glass slides were synthesized by spatially selective polymerization of 2-methoxyaniline or 2-ethoxyaniline onto micrometer-sized gas bubbles. The gas bubbles play the role of templates that direct the polymer growth in the form of spherical capsules. It was shown that the polymerization reaction is initiated at the gas/solution interface and is followed by growth extending onto the glass/solution interface. In consequence, two pathways of capsule formation can be distinguished. The first pathway involves the adsorption of gaseous bubbles onto glass, which is followed by coating the adsorbed bubbles with the polymer. This yields a relatively small number of polymeric capsules decorating the surface. In the second pathway, the gas bubbles generated in the bulk of the solution are first coated with the polymer and then adsorbed onto the glass surface (already modified with a thin polymeric film). In this process, a large number of polymeric particles accumulate on the surface. The growth of polymeric capsules was examined using several experimental techniques, including scanning electron microscopy, near-field scanning optical microscopy, UV-vis spectroscopy, and conductivity measurements.