Exploiting Chemical Switching in a Diels–Alder Polymer for Nanoscale Probe Lithography and Data Storage

Abstract

Reversibly crosslinked polymer films have properties that are beneficial to scanned‐probe data storage and lithographic applications that use thermomechanical nanoindentation as a write or expose mechanism. The novel polymer under study contains linkages based on thermally reversible Diels–Alder crosslinking. Thermomechanical properties on the nanometer scale are analyzed by indentation experiments on polymer thin films using heated tips. The underlying indentation mechanism is studied at varying tip temperatures and indentation times, revealing Arrhenius kinetics. This is in contrast to the Williams–Landau–Ferry kinetics usually observed for polymer systems. The discrepancy is explained by the reversible crosslinking incorporated into the structure of the polymer that allows switching between two different states: a rigid, highly crosslinked, low‐temperature state, and a deformable, fragmented, high‐temperature state. An individual indentation volume of less than 10–20 L (10 000 molecule pairs) is estimated. These kinetics experiments demonstrate that a chemical reaction of only a few thousand molecules can be transduced into a mechanically measurable action. The ability to cycle between two sets of properties in these materials opens up new perspectives in lithography and data storage. Examples of data storage with densities up to 1 Tb in.–2 and maskless lithography with resolution below 20 nm are demonstrated at writing times of 10 μs per bit/pixel.

Slightly crosslinked polyurethane with Diels–Alder adducts from trimethylolpropane

“…The intensity of the peaks at 2275 cm 21 attributed to the NCO groups in the polyurethane prepolymer decreased significantly after reaction with furfuryl amine, indicating most of the isocyanate in MDI-PBA-MDI prepolymer was consumed by the furfuryl amine. There was still residue isocyanate in the MDI-PBA-FA prepolymer solution, confirmed by the fact that the characteristic peaks did not disappear completely in Figure 2.…”

The Application of STM and AFM in Nanoprocess and Fabrication

“…For example: work has been done on melting of polymer nanocrystals [39] , high-density data writing and reading [40,41] , local surface glass transition [42] , and nanodecomposition [43,44] .…”

Fabrication of Reversibly Crosslinkable, 3‐Dimensionally Conformal Polymeric Microstructures

“…[10][11][12] Crosslinked honeycomb films, on flat substrates, have been achieved via chemical [13][14][15] and UV [16,17] activated reactions. UV has an advantage as it is non-evasive and can be used to create further patterns in the films -extending their versatility.…”