Self-assembly of molecules that spontaneously form ordered phases exhibiting well-defined nanoscale periodicity and shapes may be used for future Logic, Memory and intreconnects. However, until to day these have been limited to lamellae or hexagonally packed cylinders.
A team of researchers at Brookhaven National Laboratory have recently showed how soft self-assembling materials—block copolymer thin films—can be manipulated to form a diverse library of previously unreported morphologies. The processes s modules can be repeated as an iterative self-assembly as described in the figure below.
You can read all about these exciting results it in the Open Source publication in Nature Communications: Rahman, A. et al. Non-native three-dimensional blockcopolymer morphologies. Nat. Commun. 7, 13988 doi: 10.1038/ncomms13988 (2016).
(a) The responsive assembly strategy begins by depositing a neutral brush on the substrate of interest. A block copolymer (BCP) film is then spin-coated on the substrate and annealed to yield a well-defined morphology. Selective infiltration synthesis (SIS) is used to load one of the BCP domains with alumina; this process ‘fixes’ the thin film, making it robust and insoluble, and generates height variation between the domains. The fixed BCP film can be used as the substrate in a subsequent round of ordering. The height variation (which remains after depositing the neutral brush) templates the subsequent BCP layer, causing it to align and register in a well-defined way. Single-layer, bi-layer or multilayer inorganic replicas can be formed by ashing the film (exposure to O2 plasma), as shown in the right-most column. (b) Cross-sectional scanning electron microscopy (SEM) of an exemplar single-layer infiltrated nanostructure before and after ashing (lamellar-forming BCP, L36). (c) Cross-sectional SEM of an exemplar four-layer nanostructure. False-colour applied to highlight layers (from bottom to top): L104, L74, L36, C132. Scale bars are 100 nm. Released unde Creative Commons 4.0 from Rahman, A. et al. Non-native three-dimensional blockcopolymer morphologies. Nat. Commun. 7, 13988 doi: 10.1038/ncomms13988 (2016).