Poly(cyclohexylethylene)-<i>block</i>-Poly(lactide)\nOligomers for Ultrasmall Nanopatterning Using Atomic Layer Deposition

Abstract

Poly­(cyclohexylethylene)<i>-<i>block</i>-</i>poly­(lactide) (PCHE<i>–</i>PLA) block polymers were\nsynthesized through a combination of anionic polymerization, heterogeneous\ncatalytic hydrogenation and controlled ring-opening polymerization.\nOrdered thin films of PCHE–PLA with ultrasmall hexagonally\npacked cylinders oriented perpendicularly to the substrate surface\nwere prepared by spin-coating and subsequent solvent vapor annealing\nfor use in two distinct templating strategies. In one approach, selective\nhydrolytic degradation of the PLA domains generated nanoporous PCHE\ntemplates with an average pore diameter of 5 ± 1 nm corroborated\nby atomic force microscopy and grazing incidence small-angle X-ray\nscattering. Alternatively, sequential infiltration synthesis (SIS)\nwas employed to deposit Al₂O₃ selectively into\nthe PLA domains of PCHE–PLA thin films. A combination of argon\nion milling and O₂ reactive ion etching (RIE) enabled the\nreplication of the Al₂O₃ nanoarray from the\nPCHE–PLA template on diverse substrates including silicon and\ngold with feature diameters less than 10 nm.