Formation of a silica scaffold with a hyperbolic surface structure as a time-frozen glimpse by ultraviolet curing

Abstract

Triply periodic hyperbolic surfaces have been extensively investigated in various natural and artificial self-assembled systems and have attracted great attention because of their complexity and geometrical beauty. However, understanding their formation during bottom-up processes remains challenging because of the short lifetimes of structural intermediates and the soft nature of amphiphilic systems. Herein, we introduce UV light curing technology, which rapidly solidifies reaction intermediates without interfering with the final structure. The synthesis involves a miktoarm block copolymer, poly(ethylene oxide)-s-(polystyrene)2, with tetraethyl orthosilicate in a mixture of tetrahydrofuran and an aqueous HCl solution to form a silica scaffold with a shifted double diamond structure. By capturing intermediate phases at different reaction stages, we disclosed the following sequence of structural transformations: lamellar → perforated lamellar → single network → double diamond network → shifted double diamond after calcination. Our findings underscore the pivotal role of perforated lamellar structures and single networks as key intermediates, which exhibit instability conducive to transitioning into more stable double network configurations. This transformation also explains the coexistence of single and double networks observed in previous experiments and their unit cell parameter discrepancies. This research provides new insights into the formation of hyperbolic structures and the design of future self-assembly processes.

This article is part of the theme issue ‘Geometry, materials and the imagination’.