Double-Striped Metallic Patterns from PS-b-P4VP Nanostrand Templates

A new nanometallic pattern, characterized by randomly disposed double or twin one-dimensional stripes and that adds to the nanotechnology toolbox, has been obtained from a unique template possessing the nanostrand morphology. This morphology had previously been shown to form in Langmuir-Blodgett films made from a polystyrene-poly(4-vinylpyridine) (PS-P4VP) diblock copolymer blended with 3-n-pentadecylphenol (PDP). The nanostrand backbone is composed of PS, and it is bordered along both sides by a P4VP monolayer, visualized for the first time by high resolution atomic force microscopy. The exposed P4VP alongside the nanostrands serves as sites for depositing compounds attracted selectively to P4VP. Here, both gold ions (HAuCl4·3H2O) and gold nanoparticles (AuNP, 12 nm in diameter, stabilized with sodium citrate) were complexed to the P4VP. Plasma treatment of the gold ions led to double stripes of monolayer metallic gold. To obtain dense deposition of AuNP in double rows, it was necessary to acidify the AuNP aqueous solution (pH 5.2 here). The achievement of the metallic double-stripe patterns also confirms the composition of the nanostrand morphology, which up to now had been deduced indirectly. The double-stripe pattern has possible applications for plasmonic lasers, energy transport, and biosensors.