Multidimensional hierarchical self-assembly of amphiphilic cylindrical block comicelles

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Abstract:Self-assembly of molecular and block copolymer amphiphiles represents a well-established route to micelles with a wide variety of shapes and gel-like phases. We demonstrate an analogous process, but on a longer lengthscale, in which amphiphilic P-H-P and H-P-H cylindrical triblock comicelles with hydrophobic (H) or polar (P) segments that are monodisperse in length are able to self-assemble side-byside or end-to-end in non-solvents for the central or terminal segments, respectively. This allows the formation of cylindrical supermicelles and 1D or 3D superstructures that persist in both solution and the solid state. These assemblies possess multiple levels of structural hierarchy in combination with existence on a multimicron length scale, features that are generally only found in natural materials. Main Text:Amphiphiles such as molecular surfactants and block copolymers have been shown to form a rich variety of self-assembled nanoscopic structures, including spherical micelles, cylinders, nanotubes, bilayers, and vesicles as well as gel-like phases (1, 2). The construction of hierarchical colloidal materials on a longer length scale using spherical nanoparticles (3, 4), branched nanocrystals (5), nanorods (6), and nanocubes (7) has also recently been the subject of intense investigation. Control over the size, shape and composition of these nanoscopic building blocks has enabled the formation of superstructures with significant structural diversity (3, 7). Self-assembly of Janus and patchy nanoparticles formed by surface modification (8, 9) or from block copolymers (10), including diblock (11) and star (12) or linear triblock copolymers (13-15), has further broadened the range of superstructures that can be prepared.Nevertheless, despite these impressive recent advances, the use of anisotropic amphiphilic building blocks derived from soft-matter remains limited: examples include polymer-based (16) and polymer-metal hybrid nanorods (17, 18) and self-assembled nanotubes and cylinders (19,20). These approaches

Monodisperse Cylindrical Micelles and Block Comicelles of Controlled Length in Aqueous Media

“…In addition, the amphiphilicity of such block comicelles prior to the transformation of the B blocks would allow their self-assembly behavior to be explored in aqueous media. This might result in the formation of cylindrical micelle-based superstructures 59,82 with potential applications in tissue engineering or as stimuli-responsive biomaterials.…”

“…[56][57][58][59][60] Herein, in an attempt to tackle the above-mentioned limitations, we report the preparation of well-defined, water-soluble cylindrical micelles of controlled length over a broad range up to 1.10 µm, with the added advantage of having a readily functionalizable coronaforming block. Furthermore, we report the first example of the formation of water-soluble cylindrical block comicelles.…”

An investigation into the hexagonal phases formed in high-concentration dispersions of well-defined cylindrical block copolymer micelles

“…[11,12] These techniques have been used to create hierarchical self-assembled structures and superstructures in solution. [13][14][15] Previous work on the liquid crystalline phase behaviour of PFS-based cylindrical micelles dispersed in decane revealed the existence of nematic and hexagonal phases, however discussion of the results was focussed predominantly on the isotropic and nematic phases. [7] Indeed where the phase behaviour of semi-flexible rods has been reported elsewhere, [16][17][18][19][20][21][22][23] there has been little discussion of what occurs at high concentrations.…”

Synthesis and Solution Self‐Assembly of Polyisoprene‐block‐poly(ferrocenylmethylsilane): A Diblock Copolymer with an Atactic but Semicrystalline Core‐Forming Metalloblock

“…These structures were found to stack either side by side in non-solvents for the central block, or end to end in non-solvents for the terminal block, which allows the formation of a variety of 1D and 3D superlattice structures (see Figure 44). 378 These aggregates possess multiple levels of structural hierarchy on length-scales that are normally only apparent in nature. In addition, as the functionality of the micelle coronas is unchanged throughout the self-assembly process from the initial stages to the formation of superstructures.…”

“…377 As a continuation of this work on amphiphilic block comicelles, it was reported that the resulting micron-scale assemblies can be easily controlled through altering the dimensionality, functionality and ordering of the starting block comicelles. 378 Monodisperse BAB amphiphilic triblock comicelles with either hydrophilic or hydrophobic central or terminal blocks were prepared. These structures were found to stack either side by side in non-solvents for the central block, or end to end in non-solvents for the terminal block, which allows the formation of a variety of 1D and 3D superlattice structures (see Figure 44).…”