Supramolecular Materials: Self-Organized Nanostructures

Stupp, Samuel I.; LeBonheur, V.; Walker, Kathrin C.; Li, L. S.; Huggins, K. E.; Keser, M.; Amstutz, A.

doi:10.1126/science.276.5311.384

Cited by 1,079 publications

(688 citation statements)

References 14 publications

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“…1 In particular, the selfassembly of organic molecules and synthetic polymers have been extensively investigated in recent years. 2,3 These studies reported nanoscale to microscale morphologies such as spherical or cylindrical micelles, vesicles, ribbons, fibers, bowls, and toroids. [4][5][6][7][8][9] Of particular interest are stimuli-responsive materials that allow for the directed or modulated self-assembly on the nanoscale in aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular Self-Assembly of Multiblock Copolymers in Aqueous Solution

et al. 2006

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A unique pH-dependent phase behavior from a copolytner micellar solution to a collapsed hydrogel with micelles ordered in a hexagonal phase was observed. Small-angle neutron scattering (SANS) was used to follow the pH-dependent structural evolution of micelles formed in a solution of a pentablock copolymer consisting of poly((diethylaminoethyl methacrylate)-b-(ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)-b-(diethylaminoethyl methacrylate)) (PDEAEM 25-b-PEO 100-b-PPO 65-b-PEO 100-b-PDEAEM 25). Between pH 3.0 and pH 7.4, we observed the presence of charged spherical micelles. Increasing the pH of the micelle solution above pH 7.4 resulted in increasing the size of the micelles due to the increasing hydrophobicity of the PDEAEM blocks above their pK a of 7.6. The increase in size of the spherical micelles resulted in a transition to a cylindrical micelle morphology in the pH range 8.1-10.5, and at pH > 11, the copolymer solution undergoes macroscopic phase separation. Indeed, the phase separated copolymer sediments and coalesces into a hydrogel structure that consists of 25-35 wt% water. Small-angle X-ray scattering (SAXS) clearly indicated that the hydrogel has a hexagonal ordered phase. Interestingly, the process is reversible, as lowering of the pH below 7.0 leads to rapid dissolution of the solid into homogeneous solution. We believe that the hexagonal structure in the hydrogel is a result of the organization of the cylindrical micelles due to the increased hydrophobic interactions between the micelles at 70Â°C and pH 11. Thus we have developed a pH-/ temperature-dependent, reversible hierarchically self-assembling block copolymer system with structures spanning nano-to microscale dimensions. KeywordsAmes Laboratory, copolymer sediments, small-angle neutron scattering, micelles, pH effects, phase separation, self assembly, supramolecular chemistry, block copolymers Disciplines Biochemical and Biomolecular Engineering | Chemical Engineering | Polymer Science CommentsReprinted (adapted) with permission from Langmuir, 22 (4) A unique pH-dependent phase behavior from a copolymer micellar solution to a collapsed hydrogel with micelles ordered in a hexagonal phase was observed. Small-angle neutron scattering (SANS) was used to follow the pHdependent structural evolution of micelles formed in a solution of a pentablock copolymer consisting of poly((diethylaminoethyl methacrylate)-b-(ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)-b-(diethylaminoethyl methacrylate)) (PDEAEM 25 -b-PEO 100 -b-PPO 65 -b-PEO 100 -b-PDEAEM 25 ). Between pH 3.0 and pH 7.4, we observed the presence of charged spherical micelles. Increasing the pH of the micelle solution above pH 7.4 resulted in increasing the size of the micelles due to the increasing hydrophobicity of the PDEAEM blocks above their pK a of 7.6. The increase in size of the spherical micelles resulted in a transition to a cylindrical micelle morphology in the pH range 8.1-10.5, and at pH >11, the copolymer solution undergoes macroscopic phase separation...

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Section: Introductionmentioning

confidence: 99%

Supramolecular Self-Assembly of Multiblock Copolymers in Aqueous Solution

et al. 2006

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“…Here, systematic and iterative studies on designed systems will be very useful to emulate the biological self-assembly in artificial systems. Our laboratory has had this focus over the past decade, seeking to develop self-assembly codes for function in macromolecular scales (Stupp et al 1997;Hartgerink et al 2001;Zubarev et al 2001Zubarev et al , 2006. In analogy to polymers, we define the scale as that of molecular assemblies in which the collective molar mass exceeds 10 4 daltons.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular self-assembly codes for functional structures

Palmer

Velichko

Cruz

et al. 2007

Phil. Trans. R. Soc. A.

102

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Small-molecule self-assembly has proven to be a rich field for the controlled synthesis of supramolecular objects with the size scale of polymers and interesting properties. Using several recent examples from our laboratory, we discuss the development of chemical structure codes for supramolecular self-assembly objects with defined shapes. The resulting materials formed by these objects are promising for electronic functions and biological functions for regenerative medicine.

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“…Although amphiphilic diblock copolymers are usually used to produce aqueous micelles, ABC triblock copolymers have the advantage to form more complex nanostructures [4][5]. In this respect, well-defined coreshell-corona (CSC) micelles have been prepared from poly(styrene)-block-poly(2-vinylpyridine)-blockpoly(ethylene oxide) (PS-b-P2VP-b-PEO) triblock copolymers [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Morphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer

Liangcai

Gohy

Willet

et al. 2004

Polymer

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The poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer PS 200 -b-P2VP 140 -b-PEO 590 , where the subscripts refer to the number average degrees of polymerization, forms spherical micelles in water, that consist of a PS core, a pH-responsive P2VP shell and a PEO corona. This triblock has been added with homo-PS before micellization in order to increase the volume fraction of the core-forming block. The length of the added homo-PS has been varied with respect to the length of the PS core-forming block: much shorter, much longer and approximately the same. The structure of the micelles has been investigated by transmission electron microscopy, static and dynamic light scattering. Homo-PS phase separates whenever its length is larger than the one of the PS core-forming chains; otherwise this phenomenon occurs beyond a critical concentration that depends on molecular weight. The addition of homo-PS has no influence on the morphology of the micelles and on the characteristic size of both the PS core and the P2VP shell, although the hydrodynamic diameter of the micelles is decreased. Substitution of styrene for homopolystyrene results in transition from a spherical to a dominant rod-like morphology.

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Supramolecular Materials: Self-Organized Nanostructures

Cited by 1,079 publications

References 14 publications

Supramolecular Self-Assembly of Multiblock Copolymers in Aqueous Solution

Supramolecular Self-Assembly of Multiblock Copolymers in Aqueous Solution

Supramolecular self-assembly codes for functional structures

Morphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer

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