Bicontinuous Phases in Diblock Copolymer/Homopolymer Blends: Simulation and Self-Consistent Field Theory

Handle URI:
http://hdl.handle.net/10754/597667
Title:
Bicontinuous Phases in Diblock Copolymer/Homopolymer Blends: Simulation and Self-Consistent Field Theory
Authors:
Martínez-Veracoechea, Francisco J.; Escobedo, Fernando A.
Abstract:
A combination of particle-based simulations and self-consistent field theory (SCFT) is used to study the stabilization of multiple ordered bicontinuous phases in blends of a diblock copolymer (DBC) and a homopolymer. The double-diamond phase (DD) and plumber's nightmare phase (P) were spontaneously formed in the range of homopolymer volume fraction simulated via coarse-grained molecular dynamics. To the best of our knowledge, this is the first time that such phases have been obtained in continuum-space molecular simulations of DBC systems. Though tentative phase boundaries were delineated via free-energy calculations, macrophase separation could not be satisfactorily assessed within the framework of particle-based simulations. Therefore, SCFT was used to explore the DBC/homopolymer phase diagram in more detail, showing that although in many cases two-phase coexistence of a DBC-rich phase and a homopolymer-rich phase does precede the stability of complex bicontinuous phases the DD phase can be stable in a relatively wide region of the phase diagram. Whereas the P phase was always metastable with respect to macrophase separation under the thermodynamic conditions explored with SCFT, it was sometimes nearly stable, suggesting that full stability could be achieved in other unexplored regions of parameter space. Moreover, even the predicted DD- and P-phase metastability regions were located significantly far from the spinodal line, suggesting that these phases could be observed in experiments as "long-lived" metastable phases under those conditions. This conjecture is also consistent with large-system molecular dynamics simulations that showed that the time scale of mesophase formation is much faster than that of macrophase separation. © 2009 American Chemical Society.
Citation:
Martínez-Veracoechea FJ, Escobedo FA (2009) Bicontinuous Phases in Diblock Copolymer/Homopolymer Blends: Simulation and Self-Consistent Field Theory. Macromolecules 42: 1775–1784. Available: http://dx.doi.org/10.1021/ma802427a.
Publisher:
American Chemical Society (ACS)
Journal:
Macromolecules
Issue Date:
10-Mar-2009
DOI:
10.1021/ma802427a
Type:
Article
ISSN:
0024-9297; 1520-5835
Sponsors:
We thank Prof. David Morse and his student Jian Qin for providing the code and generous guidance to implement the SCFT Calculations. We also thank Prof. U. Wiesner for helpful discussions. The financial support by the NSF (grant 0756248) and by the Cornell-KAUST center is gratefully acknowledged.
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorMartínez-Veracoechea, Francisco J.en
dc.contributor.authorEscobedo, Fernando A.en
dc.date.accessioned2016-02-25T12:44:03Zen
dc.date.available2016-02-25T12:44:03Zen
dc.date.issued2009-03-10en
dc.identifier.citationMartínez-Veracoechea FJ, Escobedo FA (2009) Bicontinuous Phases in Diblock Copolymer/Homopolymer Blends: Simulation and Self-Consistent Field Theory. Macromolecules 42: 1775–1784. Available: http://dx.doi.org/10.1021/ma802427a.en
dc.identifier.issn0024-9297en
dc.identifier.issn1520-5835en
dc.identifier.doi10.1021/ma802427aen
dc.identifier.urihttp://hdl.handle.net/10754/597667en
dc.description.abstractA combination of particle-based simulations and self-consistent field theory (SCFT) is used to study the stabilization of multiple ordered bicontinuous phases in blends of a diblock copolymer (DBC) and a homopolymer. The double-diamond phase (DD) and plumber's nightmare phase (P) were spontaneously formed in the range of homopolymer volume fraction simulated via coarse-grained molecular dynamics. To the best of our knowledge, this is the first time that such phases have been obtained in continuum-space molecular simulations of DBC systems. Though tentative phase boundaries were delineated via free-energy calculations, macrophase separation could not be satisfactorily assessed within the framework of particle-based simulations. Therefore, SCFT was used to explore the DBC/homopolymer phase diagram in more detail, showing that although in many cases two-phase coexistence of a DBC-rich phase and a homopolymer-rich phase does precede the stability of complex bicontinuous phases the DD phase can be stable in a relatively wide region of the phase diagram. Whereas the P phase was always metastable with respect to macrophase separation under the thermodynamic conditions explored with SCFT, it was sometimes nearly stable, suggesting that full stability could be achieved in other unexplored regions of parameter space. Moreover, even the predicted DD- and P-phase metastability regions were located significantly far from the spinodal line, suggesting that these phases could be observed in experiments as "long-lived" metastable phases under those conditions. This conjecture is also consistent with large-system molecular dynamics simulations that showed that the time scale of mesophase formation is much faster than that of macrophase separation. © 2009 American Chemical Society.en
dc.description.sponsorshipWe thank Prof. David Morse and his student Jian Qin for providing the code and generous guidance to implement the SCFT Calculations. We also thank Prof. U. Wiesner for helpful discussions. The financial support by the NSF (grant 0756248) and by the Cornell-KAUST center is gratefully acknowledged.en
dc.publisherAmerican Chemical Society (ACS)en
dc.titleBicontinuous Phases in Diblock Copolymer/Homopolymer Blends: Simulation and Self-Consistent Field Theoryen
dc.typeArticleen
dc.identifier.journalMacromoleculesen
dc.contributor.institutionCornell University, Ithaca, United Statesen
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