A Reevaluation of Bicontinuous Cubic Phases in Starblock Copolymers

Abstract

Recently, a new equilibrium microstructure, a second bicontinuous cubic morphology similar in many respects to the ordered bicontinuous double diamond (OBDD) structure, has been identified in a weakly segregated polystyrene-polyisoprene (SI) diblock copolymer melt.1'2 X-ray diffraction indicated that the new cubic phase was more consistent with a microstructure based on the Schoen G or "gyroid" minimal surface3 than with an analogous model of the OBDD morphology based on the Schwarz D minimal surface.4 This new cubic phase was therefore entitled the "gyroid*", with the "*" symbol serving to distinguish the block copolymer morphology from the G minimal surface.Model microstructures of the OBDD and gyroid* morphologies were developed to determine the characteristics of the new cubic phase.1'2,7 In these models, the majority component material (e.g., polyisoprene) is confined to lie within a constant distance from the underlying minimal surfaces (Schwarz D for OBDD, Schoen G for gyroid*). The resulting majority component phase has constant thickness (CT), and so the * To whom correspondence should be addressed.

Structure, function, and self-assembly of single network gyroid ( I 4 1 32) photonic crystals in butterfly wing scales

“…complete absence of features at the predicted ffiffiffiffiffi 16 p and ffiffiffiffiffi 19 p peak positions do not support the assignment of the single diamond (Fd3m) space group (29) (Fig. S3).…”

“…Biological cubic membrane structures occur with double primitive (Im3m), double gyroid (Ia3d) and double diamond (Pn3m) space group symmetries (34,35). These morphologies are the very same cubic bicontinuous phases seen in block-copolymer (29,37), lyotropic lipid-water (38), and amphiphilic surfactant systems (39). The formation of complex cubic membrane structures in living cells have been hypothesized to be controlled biologically by the regulation of the expression of proteins that are intrinsic to and span the lipid-bilayer membrane (36).…”

“…5). By initially developing the thermodynamically favored double gyroid nanostructure (29,(37)(38)(39), and then transforming it into the optically more efficient single gyroid photonic crystal (43,44), these butterflies have evolved to use biological and physical mechanisms that anticipate contemporary approaches to the engineering and manufacture of photonic materials (43,44). Current engineering approaches also aim to produce single gyroid motifs from a double gyroid template (e.g., ref.…”

Thermal Study on Phase Transitions of Block Copolymers by Mesoscopic Simulation

“…For example, The PS-PI diblock copolymer can generate this ordered structure via an order-disorder phase transition, see Fig The OBDD phase has a tetrahedral arrangement of epitaxially cylinders interconnected by channels of Ia3d symmetry (Hajduk et al, 1995). The OBDD phase of PS-PI copolymer exists only in a narrow interval of values (0.37 to 0.4 volume fraction of poly(styrene)) between the regimes of the perforated layer and lamellar phases.…”

Final Report: Grant DE-FG02-05ER15682. Simulation of Complex Microphase Formation in Pure and Nanoparticle-filled Diblock Copolymers

“…While in pure DBC melts it was initially thought that the stable bicontinuous phase was the DD phase, it is now well established that the only stable bicontinuous phase in pure DBC melts is the G phase. 4,15,16 A common feature of the ordered bicontinuous phases is that their minority-component networks form a structure composed of tubes (connectors) and nodes. 9 The number of tubes intersecting in each node depends upon the specific phase.…”