Nano- and meso-porous materials have been intensively investigated due to their great potential in the variety of applications including nanofilter membrane, gas storage, gas separation, catalyst, energy conversion and storage, etc. Among so many strategies developed for nanoporous structure, the self-assembly of block copolymers (BCPs) has attracted intensive attention since BCPs containing an etchable block component can easily produce well-defined nanoporous structure by removal of the sacrificial component from microphase-separated structures. One example of a block component is polylactide (PLA) that can be readily etched by mild basic hydrolysis. Such nanoporous materials have been demonstrated to be useful as nanofiltration membranes, antireflection coatings and nanotemplates. In this work, cylinder-forming PS-b-PLA films were used to generate the nanoprous structure and shown to be able to act as a template for pattern transfer and formation of nanodots on the substrate. For the purpose, spin-coated PS-b-PLA films were annealed in toluene/THF mixture vapors. Solvent annealing produced highly-ordered, hexagonally close-packed PLA cylinders oriented normal to the surface. Subsequent NaOH wet etching selectively removed PLA domains and generated highly-ordered nanoporous structure. Here such nanoporous structure was used as a template to transfer the patterns into underlying substrates through the plasma etching and to grow the nanodots of Pt on the substrate via sputtering. All these results indicate that not only the PLA minority domains were successfully degraded with NaOH solution to form the nanopores spanning all the way through the entire film but also obtained PS nanoporous template can be used as a template for pattern transfer and nanodot growth.

Highly-ordered nanoporous thin films from PLA-containing block copolymers

246th National Meeting (2013)

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