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Greenall MJ, Derry MJ. Temperature dependence of micelle shape transitions in copolymer solutions: the role of inter-block incompatibility. SOFT MATTER 2024; 20:3628-3634. [PMID: 38619553 DOI: 10.1039/d4sm00331d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The nature of the transition between worm-like and spherical micelles in block copolymer dispersions varies between systems. In some formulations, heating drives a transition from worms to spheres, while in other systems the same transition is induced by cooling. In addition, a sphere-worm interconversion can be accompanied either by an increase or a decrease in the core solvation, even if the direction of the temperature dependence is the same. Here, self-consistent field theory is used to provide a potential explanation of this range of behaviour. Specifically, we show that, within this model, the dependence of the transition on the incompatibility χBS of the solvophobic block B and the solvent S (the parameter most closely related to the temperature) is strongly influenced by the incompatibility χAB between B and the solvophilic block A. When χAB is small (χAB < 0.1), it is found that increasing χBS produces a transition from worm-like micelles to spheres (or, more generally, from less curved to more curved structures). When χAB is above 0.1, increasing χBS drives the system from spheres to worm-like micelles. Whether a transition is observed within a realistic range of χBS is also found to depend on the fraction of solvophilic material in the copolymer. The relevance of our calculations to experiments is discussed, and we suggest that the direction of the temperature dependence may be controlled not only by the solution behaviour of the solvophobic block (upper critical solution temperature-like versus lower critical solution temperature-like) but also by χAB.
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Affiliation(s)
- M J Greenall
- School of Mathematics and Physics, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK.
| | - M J Derry
- Aston Institute for Membrane Excellence, Aston University, Birmingham, B4 7ET, UK
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Sarkar A, Thyagarajan A, Cole A, Stefik M. Widely tunable persistent micelle templates via homopolymer swelling. SOFT MATTER 2019; 15:5193-5203. [PMID: 31204753 DOI: 10.1039/c9sm00484j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The combination of precision control with wide tunability remains a challenge for the fabrication of porous nanomaterials suitable for studies of nanostructure-behavior relationships. Polymer micelle templates broadly enable porous materials, however micelle equilibration hampers independent pore and wall size control. Persistent micelle templates (PMT) have emerged as a kinetic controlled platform that uniquely decouples the control of pore and wall dimensions. Here, chain exchange is inhibited to preserve a constant template dimension (pore size) despite the shifting equilibrium while materials are added between micelles. Early PMT demonstrations were synthesis intensive with limited 1-1.3× pore size tuning for a given polymer. Here we demonstrate PMT swelling with homopolymer enables 1-3.2× (13.3-41.9 nm) pore size variation while maintaining a monomodal distribution with up to 250 wt% homopolymer, considerably higher than the ∼90 wt% limit found for equilibrating micelles. These swollen PMTs enabled nanomaterial series with constant pore size and precision varied wall-thickness. Kinetic size control here is unexpected since the homopolymer undergoes dynamic exchange between micelles. The solvent selection influenced the time window before homopolymer phase separation, highlighting the importance of considering homopolymer-solvent interactions. This is the first PMT demonstration with wide variation of both the pore and wall dimensions using a single block polymer. Lastly this approach was extended to a 72 kg mol-1 block polymer to enable a wide 50-290 nm range of tunable macropores. Here the use of just two different block polymers and one homopolymer enabled wide ranging pore sizes spanning from 13.3-290 nm (1-22×).
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Affiliation(s)
- Amrita Sarkar
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC, USA.
| | - Akshay Thyagarajan
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC, USA.
| | - August Cole
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC, USA.
| | - Morgan Stefik
- Department of Chemistry & Biochemistry, University of South Carolina, Columbia, SC, USA.
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Coarse-grained modelling of self-assembling poly(ethylene glycol)/poly(lactic acid) diblock copolymers. JOURNAL OF POLYMER RESEARCH 2018. [DOI: 10.1007/s10965-018-1457-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Affiliation(s)
- M. J. Greenall
- Institute of Mathematics,
Physics and Computer Science, Physical Sciences Building, Aberystwyth University, Aberystwyth SY23 3BZ, United Kingdom
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Yang S, Lei Z, Hu N, Chen EQ, Shi AC. Regulating block copolymer phases via selective homopolymers. J Chem Phys 2015; 142:124903. [PMID: 25833605 DOI: 10.1063/1.4915538] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The phase behavior of strongly segregated AB diblock copolymer and selective C homopolymer blends is examined theoretically using a combination of strong stretching theory (SST) and self-consistent field theory (SCFT). The C-homopolymer is immiscible with the B-blocks but strongly attractive with the A-blocks. The effect of homopolymer content on the order-order phase transitions is analyzed. It is observed that, for AB diblock copolymers with majority A-blocks, the addition of the C-homopolymers results in lamellar to cylindrical to spherical phase transitions because of the A/C complexation. For diblock copolymers with minor A-blocks, adding C-homopolymers leads to transitions from spherical or cylindrical morphology with A-rich core to lamellae to inverted cylindrical and spherical morphologies with B-rich core. The results from analytical SST and numerical SCFT are in good agreement within most regions of the phase diagram. But the deviation becomes more obvious when the composition of A-blocks is too small and the content of added C-homopolymers is large enough, where the SCFT predicts a narrow co-existence region between different ordered phases. Furthermore, it is found that the phase behavior of the system is insensitive to the molecular weight of C-homopolymer.
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Affiliation(s)
- Shuang Yang
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Zhen Lei
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Nan Hu
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Er-Qiang Chen
- Beijing National Laboratory for Molecular Sciences, Department of Polymer Science and Engineering and Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - An-Chang Shi
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
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Greenall MJ, Marques CM. Can amphiphile architecture directly control vesicle size? PHYSICAL REVIEW LETTERS 2013; 110:088301. [PMID: 23473205 DOI: 10.1103/physrevlett.110.088301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 10/09/2012] [Indexed: 06/01/2023]
Abstract
Bilayer membranes self-assembled from simple amphiphiles in solution always have a planar ground-state shape. This is a consequence of several internal relaxation mechanisms of the membrane and prevents the straightforward control of vesicle size. Here, we show that this principle can be circumvented and that direct size control by molecular design is a realistic possibility. Using coarse-grained calculations, we design tetrablock copolymers that form membranes with a preferred curvature and demonstrate how to form low-polydispersity vesicles while suppressing micellization.
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Affiliation(s)
- Martin J Greenall
- Institut Charles Sadron, University of Strasbourg, CNRS-UPR 22, 23, rue du Loess, 67034 Strasbourg, France
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Greenall MJ, Gompper G. Simple and Complex Micelles in Amphiphilic Mixtures: A Coarse-Grained Mean-Field Study. Macromolecules 2011. [DOI: 10.1021/ma2014639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Martin J. Greenall
- Theoretical
Soft Matter and Biophysics, Institute for Complex Systems, Forschungszentrum Jülich, 52425 Jülich,
Germany
- Institut Charles Sadron, 23, rue du Loess, 67034 Strasbourg,
France
| | - Gerhard Gompper
- Theoretical
Soft Matter and Biophysics, Institute for Complex Systems, Forschungszentrum Jülich, 52425 Jülich,
Germany
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Zhou J, Shi AC. Critical Micelle Concentration of Micelles with Different Geometries in Diblock Copolymer/Homopolymer Blends. MACROMOL THEOR SIMUL 2011. [DOI: 10.1002/mats.201100042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Greenall MJ, Schuetz P, Furzeland S, Atkins D, Buzza DMA, Butler MF, McLeish TCB. Controlling the Self-Assembly of Binary Copolymer Mixtures in Solution through Molecular Architecture. Macromolecules 2011. [DOI: 10.1021/ma2008546] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Peter Schuetz
- Unilever R&D Colworth, Colworth Park, Sharnbrook, MK44 1LQ, U.K
| | - Steve Furzeland
- Unilever R&D Colworth, Colworth Park, Sharnbrook, MK44 1LQ, U.K
| | | | - D. Martin A. Buzza
- Department of Physics, The University of Hull, Cottingham Road, Hull HU6 7RX, U.K
| | | | - Tom C. B. McLeish
- Department of Physics, Durham University, South Road, Durham DH1 3LE, U.K
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Greenall MJ, Gompper G. Bilayers connected by threadlike micelles in amphiphilic mixtures: a self-consistent field theory study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:3416-3423. [PMID: 21381728 DOI: 10.1021/la200138b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Binary mixtures of amphiphiles in solution can self-assemble into a wide range of structures when the two species individually form aggregates of different curvatures. A specific example of this is seen in solutions of lipid mixtures where the two species form lamellar structures and spherical micelles, respectively. Here, vesicles connected by threadlike micelles can form in a narrow concentration range of the sphere-forming lipid. We present a study of these structures based on self-consistent field theory (SCFT), a coarse-grained model of amphiphiles. First, we show that the addition of sphere-forming lipid to a solution of lamella-former can lower the free energy of cylindrical, threadlike micelles and hence encourage their formation. Next, we demonstrate the coupling between composition and curvature; specifically, that increasing the concentration of sphere-former in a system of two bilayers connected by a thread leads to a transfer of amphiphile to the thread. We further show that the two species are segregated within the structure, with the concentration of sphere-former being significantly higher in the thread. Finally, the addition of larger amounts of sphere-former is found to destabilize the junctions linking the bilayers to the cylindrical micelle, leading to a breakdown of the connected structures. The degree of segregation of the amphiphiles and the amount of sphere-former required to destabilize the junctions is shown to be sensitive to the length of the hydrophilic block of the sphere-forming amphiphiles.
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Affiliation(s)
- Martin J Greenall
- Theoretical Soft Matter and Biophysics, Institute for Complex Systems, Forschungszentrum Jülich, 52425 Jülich, Germany
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Holoubek J, Baldrian J, Hromádková J, Steinhart M. Self-assembled structures in polystyrene-block-polyisoprene-blend-polystyrene and polystyrene-block-poly(methyl methacrylate)-blend-polystyrene or -blend-poly(methyl methacrylate) in the strong segregation regime. POLYM INT 2010. [DOI: 10.1002/pi.2994] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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