Nanotubes from 6-arm star-shaped (PMMA-b-PS)₆ thin films

Fabrication of nanotube arrays has attracted much attention because of potential applications such as photo catalytics and sensors. Although nanotubes have been formed from core-shell cylindrical morphology in a triblock terpolymer, an appropriate solvent annealing should be done.
Here, we obtained nanotube array by changing the chain architecture of block copolymers from linear to star shape. We synthesized 6-arm star-shaped poly(methyl metacrylate)-block-polystyrene copolymer [(PMMA-b-PS)₆] having a fixed volume fraction of PMMA with 0.50. When the film thickness was n L₀ (n is integer and L₀ is the lamellar domain spacing), nanotube arrays were obtained after thermal annealing. We also investigated the surface reconstruction depending on film thickness, annealing time, and substrate.