Control of Morphology through Polymer−Solvent Interactions in Crew-Cut Aggregates of Amphiphilic Block Copolymers

Yu, Yingning; Eisenberg, Adi

doi:10.1021/ja9709740

Cited by 354 publications

(331 citation statements)

References 13 publications

(18 reference statements)

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“…42,44 A common solvent is needed to dissolve both the hydrophobic and hydrophilic blocks to form a copolymer solution before the precipitant is added to induce self-assembly. Different common solvents change the relative coil dimensions of both the core and corona chains.…”

Section: Water Content and Nature Of The Common Solventmentioning

confidence: 99%

“…The relative coil dimensions can influence the morphology in the same way that the packing factor influences the morphologies of small-molecule amphiphile aggregates. Yu and Eisenberg 44 showed that spherical aggregates were obtained from PS 500 -b-PAA 58 in DMF, but vesicles were obtained when the initial solvent was tetrahydrofuran (THF) or dioxane. At the onset of micellization, the core of the aggregates was larger in THF and in dioxane than in DMF.…”

Section: Water Content and Nature Of The Common Solventmentioning

confidence: 99%

“…The control of the block copolymer aggregates can be achieved not only with single solvents but also with mixed solvents. Using the polystyrene-bpoly(4-vinyl pyridine methyl iodide) (PS 195 -bP4VPMeI 18 ) copolymer, Yu and Eisenberg 44 obtained spheres in pure THF and LCMs in pure dioxane, but using a mixture of 60/40 (w/w) THF/dioxane, they obtained rods, and from a mixture of 50/50 (w/w) THF/ dioxane, they obtained vesicles. Similarly, for the PS 200 -b-PAA 18 copolymer, they obtained spheres and LCMs from pure DMF and pure THF, respectively; using a mixed solvent system of DMF and THF resulted in the formation of either rods (95/5 w/w DMF/THF) or vesicles (75/25 w/w DMF/THF), depending on the solvent composition.…”

Section: Water Content and Nature Of The Common Solventmentioning

confidence: 99%

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Preparation of block copolymer vesicles in solution

Soo

Eisenberg

2004

J Polym Sci B Polym Phys

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365

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Block copolymer vesicles can be prepared in solution from a variety of different amphiphilic systems. Polystyreneblock-poly(acrylic acid), polystyrene-block-poly(ethylene oxide), and many other block copolymer systems can produce vesicles of a wide range of sizes; those in the range of 100 -1000 nm have been explored extensively. Different factors, such as the absolute and relative block lengths, the presence of additives (ions, homopolymers, and surfactants), the water content in the solvent mixture, the nature and composition of the solvent, the temperature, and the polydispersity of the hydrophilic block, provide control over the types of vesicles produced. Their high stability, resistance to many external stimuli, and ability to package both hydrophilic and hydrophobic compounds make them excellent candidates for use in the medical, pharmaceutical, and environmental fields.

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Section: Water Content and Nature Of The Common Solventmentioning

confidence: 99%

Section: Water Content and Nature Of The Common Solventmentioning

confidence: 99%

Section: Water Content and Nature Of The Common Solventmentioning

confidence: 99%

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Preparation of block copolymer vesicles in solution

Soo

Eisenberg

2004

J Polym Sci B Polym Phys

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365

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“…Studies to determine the kinetics of block copolymer micellization (14)(15)(16) and the kinetics and mechanisms for transformation of assembly morphologies (17)(18)(19) have become active areas of research. For a given block copolymer composition, the introduction of ions and alteration of the solution pH (20)(21)(22), modification of the solvent composition (23)(24)(25), and changes in the polymer concentration (26,27) have been found to effect reorganization of block copolymer supramolecular assemblies. The identification of methodologies that allow for observation (28) and accurate manipulation (19) of the supramolecular assembly processes is critical for the preparation and development of advanced nanostructured materials.…”

mentioning

confidence: 99%

Chemically induced supramolecular reorganization of triblock copolymer assemblies: Trapping of intermediate states via a shell-crosslinking methodology

Remsen

Clark

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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The mechanism of morphological phase transitions was studied for rod-shaped supramolecular assemblies comprised of a poly(acrylic acid)-block-poly(methyl acrylate)-block-polystyrene (PAA 90-b-PMA80-b-PS100) triblock copolymer in 33% tetrahydrofuran͞water after perturbation by reaction with a positively charged water-soluble carbodiimide. Tetrahydrofuran solvation of the hydrophobic core domain provided the dynamic nature required for the rod-to-sphere phase transition to be complete within 30 min. The intermediate morphologies such as fragmenting rods and pearl-necklace structures were trapped kinetically by the subsequent addition of a diamino crosslinking agent, which underwent covalent crosslinking of the shell layer. Alternatively, shellcrosslinked rod-shaped nanostructures with preserved morphology were obtained by the addition of the crosslinking agent before the addition of the carbodiimide, which allowed for the shell crosslinking to be performed at a faster rate than the morphological reorganization. The formation of robust shell-crosslinked nanostructures provides a methodology by which the morphological evolution processes can be observed, and it allows access to otherwise thermodynamically unstable nanostructures. The versatility of the solution-state assembly of block copolymers (1, 2) has attracted much interest toward the preparation of unique nanostructured materials possessing different compositions, shapes, and structures (3-12). Controlled assembly of block copolymers depends on a number of factors. The equilibrium between micellar assemblies and individual polymer chains involves a delicate balance of supramolecular polymerpolymer and polymer-solvent interactions, which provides a lever of enthalpic and entropic control (13) for the directed evolution of micellar morphologies with changes in the solution conditions. Studies to determine the kinetics of block copolymer micellization (14-16) and the kinetics and mechanisms for transformation of assembly morphologies (17-19) have become active areas of research. For a given block copolymer composition, the introduction of ions and alteration of the solution pH (20-22), modification of the solvent composition (23-25), and changes in the polymer concentration (26, 27) have been found to effect reorganization of block copolymer supramolecular assemblies. The identification of methodologies that allow for observation (28) and accurate manipulation (19) of the supramolecular assembly processes is critical for the preparation and development of advanced nanostructured materials.Spherical, rod-like, and vesicular assemblies are observed commonly for the supramolecular assembly of amphiphilic block copolymers. The covalent stabilization of such assemblies is facilitated by regioselective crosslinking chemistry (29, 30), performed within the core domain, throughout the shell layer, or at an intermediate radial layer. It is interesting to note that as focus has shifted from fullerenes to carbon nanotubes for carbon-based nanostructures, interest also has ...

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“…[14] The attractiveness of the latter approach lies in the fact that the micellar films can be readily prepared on a wide variety of substrates, and in addition, their dimensions and spacing can be tuned in a straight-forward manner, without having to change the polymer molecular weights. [15,16] Micellar thin films, even in their as-coated form, can be used for structuring surfaces without the need for additional processing steps. We report here an interesting approach to create nanopatterned selfassembled monolayers (SAMs) with feature dimensions in the sub-100 nm regime, and with periodicity of 100 nm, starting from thin films of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymer reverse micellar thin films on silicon surfaces.…”

mentioning

confidence: 99%

Nanopatterned Self‐Assembled Monolayers by Using Diblock Copolymer Micelles as Nanometer‐Scale Adsorption and Etch Masks

Krishnamoorthy¹,

Pugin²,

Brugger³

et al. 2008

Advanced Materials

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Nanopatterned self‐assembled monolayers (SAMs) are obtained from a simple, straight‐forward procedure by using masks derived from monolayers of block copolymer micelles. The nanopatterned SAMs consist of regularly spaced circular hydrophilic areas with diameters of approximately 60 nm on a continous hydrobhopic background or vice versa. The surfaces are shown to be excellent tools for the preparation of arrays of nanocrystals.

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Control of Morphology through Polymer−Solvent Interactions in Crew-Cut Aggregates of Amphiphilic Block Copolymers

Cited by 354 publications

References 13 publications

Preparation of block copolymer vesicles in solution

Preparation of block copolymer vesicles in solution

Chemically induced supramolecular reorganization of triblock copolymer assemblies: Trapping of intermediate states via a shell-crosslinking methodology

Nanopatterned Self‐Assembled Monolayers by Using Diblock Copolymer Micelles as Nanometer‐Scale Adsorption and Etch Masks

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