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Cheng VA, Walker LM. Transport of nanoparticulate material in self-assembled block copolymer micelle solutions and crystals. Faraday Discuss 2016; 186:435-54. [DOI: 10.1039/c5fd00122f] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water soluble poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) [PEO–PPO–PEO] triblock copolymers self-assemble into thermoreversible micellar crystals comprised of periodically spaced micelles. The micelles have PPO cores surrounded by hydrated PEO coronas and the dimensions of the unit cell of the organized micelles is on the order of several to tens of nanometers. Fluorescence recovery after photobleaching (FRAP) is used to quantify nanoparticle transport in these nanostructured polymer micelle systems. Diffusivity of bovine serum albumin (BSA, Dh ∼ 7 nm) is quantified across a wide range of polymer, or micelle, concentrations covering both the disordered fluid as well as the structured micellar crystal to understand the effects of nanoscale structure on particle transport. Measured particle diffusivity in these micellar systems is reduced by as much as four orders of magnitude when compared to diffusivity in free solution. Diffusivity in the disordered micellar fluid is best understood in terms of diffusion through a polymeric solution, while transport in the structured micellar phase is possibly due to hopping between interstitial sites. These results not only show that the nanoscale structures of the micelles have a measureable impact on particle diffusivity, but also demonstrate the ability to tune nanoscale transport in self-assembled materials.
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Affiliation(s)
- Vicki A. Cheng
- Center for Complex Fluids Engineering
- Department of Chemical Engineering
- Carnegie Mellon University
- Pittsburgh
- USA
| | - Lynn M. Walker
- Center for Complex Fluids Engineering
- Department of Chemical Engineering
- Carnegie Mellon University
- Pittsburgh
- USA
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Clifton LA, Sanders MR, Castelletto V, Rogers SE, Heenan RK, Neylon C, Frazier RA, Green RJ. Puroindoline-a, a lipid binding protein from common wheat, spontaneously forms prolate protein micelles in solution. Phys Chem Chem Phys 2011; 13:8881-8. [PMID: 21451840 DOI: 10.1039/c0cp02247k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The self-assembly in solution of puroindoline-a (Pin-a), an amphiphilic lipid binding protein from common wheat, was investigated by small angle neutron scattering, dynamic light scattering and size exclusion chromatography. Pin-a was found to form monodisperse prolate ellipsoidal micelles with a major axial radius of 112 ± 4.5 Å and minor axial radius of 40.4 ± 0.18 Å. These protein micelles were formed by the spontaneous self-assembly of 38 Pin-a molecules in solution and were stable over a wide pH range (3.5-11) and at elevated temperatures (20-65 °C). Pin-a micelles could be disrupted upon addition of the non-ionic surfactant dodecyl-β-maltoside, suggesting that the protein self-assembly is driven by hydrophobic forces, consisting of intermolecular interactions between Trp residues located within a well-defined Trp-rich domain of Pin-a.
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Affiliation(s)
- Luke A Clifton
- ISIS Spallation Neutron Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, OX11 0QX, UK.
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de Bruyn JR, Oppong FK. Microrheology and dynamics of an associative polymer. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2010; 31:25-35. [PMID: 20175286 DOI: 10.1140/epje/i2010-10545-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We study the microscopic viscoelastic properties and relaxation dynamics of solutions of a side-chain associative polymer, hydrophobically modified hydroxyethyl cellulose (hmHEC). Dynamic light scattering from small tracer particles suspended in the polymer solutions is used to determine their viscous and elastic moduli on the scale of the particles. Bulk-scale viscoelastic properties are measured by shear rheometry. The motion of the tracer particles in hmHEC is diffusive at short times and subdiffusive at intermediate and long times. The long-time subdiffusive motion was not observed in parallel experiments on unmodified HEC solutions, and is explained in terms of hindered reptation of the hydrophobically modified polymer chains in the associative network. Dynamic light scattering from the polymer molecules themselves shows that chain relaxation in hmHEC is dominated by slow concentration-dependent processes due to the large-scale associative network structure, while that in HEC is dominated by fast concentration independent Rouse-like dynamics.
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Affiliation(s)
- J R de Bruyn
- Department of Physics and Astronomy, University of Western Ontario, London, Canada
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Kostko AF, Harden JL, McHugh MA. Dynamic Light Scattering Study of Concentrated Triblock Copolymer Micellar Solutions under Pressure. Macromolecules 2009. [DOI: 10.1021/ma802503s] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A. F. Kostko
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, Virginia 23284
- Department of Physics, St. Petersburg State University of Refrigeration and Food Engineering, St. Petersburg, 191002, Russia
| | - J. L. Harden
- Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5 Canada
| | - M. A. McHugh
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, Virginia 23284
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Castro E, Barbosa S, Juárez J, Taboada P, Katime IA, Mosquera V. Influence of External Factors on the Micellization Process and Aggregate Structure of Poly(oxy)styrene−Poly(oxy)ethylene Block Copolymers. J Phys Chem B 2008; 112:5296-304. [DOI: 10.1021/jp7112895] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Emilio Castro
- Grupo de Física de Coloides y Polímeros, Grupo de Sistemas Complejos, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Santiago de Compostela, Spain, and Grupo de Nuevos Materiales y Espectroscopia Supramolecular, Departamento de Química-Física, Facultad de Ciencia y Tecnología, Campus de Leioa, Universidad del País Vasco, Apartado 644, Bilbao, Spain
| | - Silvia Barbosa
- Grupo de Física de Coloides y Polímeros, Grupo de Sistemas Complejos, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Santiago de Compostela, Spain, and Grupo de Nuevos Materiales y Espectroscopia Supramolecular, Departamento de Química-Física, Facultad de Ciencia y Tecnología, Campus de Leioa, Universidad del País Vasco, Apartado 644, Bilbao, Spain
| | - Josué Juárez
- Grupo de Física de Coloides y Polímeros, Grupo de Sistemas Complejos, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Santiago de Compostela, Spain, and Grupo de Nuevos Materiales y Espectroscopia Supramolecular, Departamento de Química-Física, Facultad de Ciencia y Tecnología, Campus de Leioa, Universidad del País Vasco, Apartado 644, Bilbao, Spain
| | - Pablo Taboada
- Grupo de Física de Coloides y Polímeros, Grupo de Sistemas Complejos, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Santiago de Compostela, Spain, and Grupo de Nuevos Materiales y Espectroscopia Supramolecular, Departamento de Química-Física, Facultad de Ciencia y Tecnología, Campus de Leioa, Universidad del País Vasco, Apartado 644, Bilbao, Spain
| | - Issa A. Katime
- Grupo de Física de Coloides y Polímeros, Grupo de Sistemas Complejos, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Santiago de Compostela, Spain, and Grupo de Nuevos Materiales y Espectroscopia Supramolecular, Departamento de Química-Física, Facultad de Ciencia y Tecnología, Campus de Leioa, Universidad del País Vasco, Apartado 644, Bilbao, Spain
| | - Víctor Mosquera
- Grupo de Física de Coloides y Polímeros, Grupo de Sistemas Complejos, Departamento de Física de la Materia Condensada, Facultad de Física, Universidad de Santiago de Compostela, Santiago de Compostela, Spain, and Grupo de Nuevos Materiales y Espectroscopia Supramolecular, Departamento de Química-Física, Facultad de Ciencia y Tecnología, Campus de Leioa, Universidad del País Vasco, Apartado 644, Bilbao, Spain
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Verduzco R, Scruggs NR, Sprunt S, Palffy-Muhoray P, Kornfield JA. Director dynamics in liquid-crystal physical gels. SOFT MATTER 2007; 3:993-1002. [PMID: 32900049 DOI: 10.1039/b700871f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Nematic liquid-crystal (LC) elastomers and gels have a rubbery polymer network coupled to the nematic director. While LC elastomers show a single, non-hydrodynamic relaxation mode, dynamic light-scattering studies of self-assembled liquid-crystal gels reveal orientational fluctuations that relax over a broad time scale. At short times, the relaxation dynamics exhibit hydrodynamic behavior. In contrast, the relaxation dynamics at long times are non-hydrodynamic, highly anisotropic, and increase in amplitude at small scattering angles. We argue that the slower dynamics arise from coupling between the director and the physically associated network, which prevents director orientational fluctuations from decaying completely at short times. At long enough times the network restructures, allowing the orientational fluctuations to fully decay. Director dynamics in the self-assembled gels are thus quite distinct from those observed in LC elastomers in two respects: they display soft orientational fluctuations at short times, and they exhibit at least two qualitatively distinct relaxation processes.
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Affiliation(s)
- Rafael Verduzco
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Blvd., Pasadena, California, USA.
| | - Neal R Scruggs
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Blvd., Pasadena, California, USA.
| | - Samuel Sprunt
- Department of Physics, Liquid Crystal Institute, Kent State University, Kent, Ohio, USA.
| | | | - Julia A Kornfield
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Blvd., Pasadena, California, USA.
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Kelarakis A, Crassous JJ, Ballauff M, Yang Z, Booth C. Micellar spheres in a high frequency oscillatory field. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:6814-7. [PMID: 16863225 DOI: 10.1021/la0607860] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The viscoelasticity of aqueous micellar solutions of two oxyethylene/oxybutylene block copolymers (E(92)B(18) and B(20)E(510)) has been investigated using a torsional resonator operated at 26 kHz. For both systems considered, values of the dynamic viscosity (eta'(infinity)) point to partial draining of the micellar corona induced by the high-frequency oscillatory field. At low effective volume fractions, values of the elastic modulus (G'(infinity)) indicate that the repulsive interactions between micelles can be modeled by a power law function u(r) proportional to 1/r(nu) with exponents close to 13 and 6 for copolymers E(92)B(18) and B(20)E(510) respectively. At a critical copolymer concentration (c*) plots of log(G'(infinity)) against log(c) deviate from the straight lines established at low concentrations, implying that the systems undergo ergodic/nonergodic transitions.
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Affiliation(s)
- Antonis Kelarakis
- Physikalishe Chemie I, Universität Bayreuth, Universitätsstrasse 30, 95440 Bayreuth, Germany.
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