Liquid Phase Infiltration of Block Copolymers

Abstract

Novel materials with defined composition and structures at the nanoscale are increasingly desired in several research fields spanning a wide range of applications. The development of new approaches of synthesis that provide such control is therefore required in order to relate the material properties to its functionalities. Self-assembling materials such as block copolymers (BCPs), in combination with liquid phase infiltration (LPI) processes, represent an ideal strategy for the synthesis of inorganic materials into even more complex and functional features. This review provides an overview of the mechanism involved in the LPI, outlining the role of the different polymer infiltration parameters on the resulting material properties. We report newly developed methodologies that extend the LPI to the realisation of multicomponent and 3D inorganic nanostructures. Finally, the recently reported implementation of LPI into different applications such as photonics, plasmonics and electronics are highlighted.

Block Copolymer-Templated, Single-Step Synthesis of Transition Metal Oxide Nanostructures for Sensing Applications

“…This step is followed by the selective infusion of an inorganic precursor into one of the BCP blocks or its selective removal and subsequent deposition of the inorganic material in the created voids. Recent reviews of the most popular BCP-templated synthesis techniques have been provided by Cummins et al and Subramanian et al BCP infusion techniques include vapor phase sequential infiltration synthesis (SIS), which utilizes volatile organometallic precursors that display preferential absorption to one of the blocks that, after conversion, results in metal oxide nanostructures (such as Al 2 O 3 , ZnO, or TiO 2 ). − A complementary approach, wet chemical conversion, employs the absorption of aqueous metal complexes and their coordination with poly­(vinylpyridine) blocks, yielding metallic Pt, Au, Cu, Co, and Ni nanopatterns. − Unlike these additive infusion methods, one of the blocks of a BCP template can be selectively removed by chemical etching and backfilled (e.g., by electrodeposition) with an inorganic material. This approach, which requires conductive support of the BCP films, has been demonstrated for a range of metals and BCP morphologies. − An even simpler method for generating metallic or oxide nanostructure templates has been proposed by Ghoshal et al, who spin-coated metal salt solutions over pre-ordered BCP films that contained a poly­(ethylene oxide) (PEO) block as a host for inorganic salts and demonstrated the synthesis of various nanopatterns containing iron, copper, titanium, and cobalt oxides. , A similar method that also used PEO as a hosting block was explored by Xu et al to fabricate arrays of cobalt ferrite nanodots …”