Poly(cyclohexylethylene)-block-Poly(lactide) Oligomers for Ultrasmall Nanopatterning Using Atomic Layer Deposition

Poly(cyclohexylethylene)-block-poly(lactide) (PCHE-PLA) block polymers were synthesized through a combination of anionic polymerization, heterogeneous catalytic hydrogenation and controlled ring-opening polymerization. Ordered thin films of PCHE-PLA with ultrasmall hexagonally packed cylinders oriented perpendicularly to the substrate surface were prepared by spin-coating and subsequent solvent vapor annealing for use in two distinct templating strategies. In one approach, selective hydrolytic degradation of the PLA domains generated nanoporous PCHE templates with an average pore diameter of 5 ± 1 nm corroborated by atomic force microscopy and grazing incidence small-angle X-ray scattering. Alternatively, sequential infiltration synthesis (SIS) was employed to deposit Al₂O₃ selectively into the PLA domains of PCHE-PLA thin films. A combination of argon ion milling and O₂ reactive ion etching (RIE) enabled the replication of the Al₂O₃ nanoarray from the PCHE-PLA template on diverse substrates including silicon and gold with feature diameters less than 10 nm.