A mean-field phase diagram for conformationally symmetric diblock melts using the standard Gaussian polymer model is presented. Our calculation, which traverses the weak- to strong-segregation regimes, is free of traditional approximations. Regions of stability are determined for disordered (DIS) melts and for ordered structures including lamellae (L), hexagonally packed cylinders (H), body-centered cubic spheres (QIm3m), close-packed spheres (CPS), and the bicontinuous cubic network with Ia3d symmetry (QIa3d). The CPS phase exists in narrow regions along the order−disorder transition for χN ≥ 17.67. Results suggest that the QIa3d phase is not stable above χN ∼ 60. Along the L/QIa3d phase boundaries, a hexagonally perforated lamellar (HPL) phase is found to be nearly stable. Our results for the bicontinuous Pn3m cubic (QPn3m) phase, known as the OBDD, indicate that it is an unstable structure in diblock melts. Earlier approximation schemes used to examine mean-field behavior are reviewed, and compa...

Unifying Weak- and Strong-Segregation Block Copolymer Theories

Self-assembly is commonly used to construct complex nanostructures from soft matter. Now, using the living crystallization-driven self-assembly approach, controlled nanostructure growth in both one and two dimensions has been achieved. Uniform lenticular multiblock platelets, as well as hierarchical structures analogous to nanoscale single- and double-headed arrows and spears have been prepared with controlled sizes in two dimensions.

Tailored hierarchical micelle architectures using living crystallization-driven self-assembly in two dimensions

This Perspective outlines recent advances concerning the formation and potential uses of block copolymer micelles, a class of soft-matter-based nanoparticles of growing importance. As a result of rapidly expanding interest since the mid-1990s, substantial advances have been reported in terms of the development of morphological diversity, structural complexity, control over micelle dimensions, scale-up, and applications in a range of areas from nanocomposites to nanomedicine.

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50th Anniversary Perspective: Functional Nanoparticles from the Solution Self-Assembly of Block Copolymers

Confined crystallization of polymeric materials

We report on the solution-state assembly of all-conjugated polythiophene diblock copolymers containing nonpolar (hexyl) and polar (triethylene glycol) side chains. The polar substituents provide a large contrast in solubility, enabling formation of stably suspended crystalline fibrils even under very poor solvent conditions for the poly(3-hexylthiophene) block. For appropriate block ratios, complexation of the triethylene glycol side chains with added potassium ions drives the formation of helical nanowires that further bundle into superhelical structures.

http://absimage.aps.org/image/MAR11/MWS_MAR11-2010-005155.pdf

Wei-Na He

Papers

Crystallization assisted self-assembly of semicrystalline block copolymers