Microphase separation in polydisperse miktoarm star copolymers

Aliev, M. A.; Kuzminyh, N.Yu.

doi:10.1016/j.physa.2011.05.013

Cited by 7 publications

(5 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In comparison to the cocontinuous window for S 11k L 10k (ω PLA = 0.32–0.62, shown as dotted lines), Figure c demonstrates that increasing the PLA dispersity both widens the cocontinuous window (ω PLA = 0.32–0.72, shaded area) and shifts its center toward larger PLA mass fraction. This is consistent with the behavior of linear block copolymers, where greater dispersity is known to both promote formation of disordered cocontinuous phases − and also favor the location of the high dispersity block on the inward side of curved interfaces, ,,− due to the tendency for increased dispersity in length of the minority domains to relieve packing frustration. Interestingly, when PLA is the majority phase, the overall d spacing has a weak dependence on PLA dispersity (Figure b) because it is more sensitive to the preferred spacing of the PS minority domains, as discussed in the previous section.…”

Section: Resultssupporting

confidence: 81%

Effects of Randomly End-Linked Copolymer Network Parameters on the Formation of Disordered Cocontinuous Phases

Zeng

Hayward

2019

Macromolecules

View full text Add to dashboard Cite

Randomly end-linked copolymer networks (RECNs) provide a robust route to cocontinuous nanoscale structures, yielding opportunities to integrate desirable and distinct properties of the constituent materials. In this report, we rely on gravimetric and mechanical analysis of polystyrene (PS)/poly(dl-lactide) (PLA) RECNs to characterize the continuity of both phases as a function of four key network parameters. (1) For symmetric (M n,PS ≈ M n,PLA) RECNs, variations in strand length reveal a critical segregation strength of χ(N PS + N PLA) ≈ 11 required for microphase separation, above which the disordered cocontinuous phase spans roughly 30 wt % in composition, with dispersed domains of the minority phase residing on either side. Increasing the strand length above this threshold increases the characteristic d spacing but has little effect on the boundaries of the cocontinuous phase. (2) For asymmetric strand lengths, M n,PS ≠ M n,PLA, the d spacing is shifted to adopt the preferred size set by the minority domains, but the breadth and location of the cocontinuous window are not altered. (3) An increase in the dispersity Đ of PLA strands widens the cocontinuous window and shifts it toward the PLA-rich end of the phase diagram. (4) Finally, an increase in the dispersity in junction functionality f expands the cocontinuous window toward both sides of the phase diagram, yielding an overall width of roughly 45 wt %. The understanding provided on how network parameters influence self-assembly of RECNs offers guidelines for the robust design of cocontinuous nanostructures.

show abstract

Section: Resultssupporting

confidence: 81%

Effects of Randomly End-Linked Copolymer Network Parameters on the Formation of Disordered Cocontinuous Phases

Zeng

Hayward

2019

Macromolecules

View full text Add to dashboard Cite

show abstract

“…Intuitively, copolymers with well-defined molecular weights and small polydispersities are needed to self-assemble into highly ordered morphologies. However, the literature has shown that well-ordered morphologies can still be achieved in copolymers with wide molecular weight distributions. − In polydisperse block copolymers, shorter chains preferred to localize at the interface between two microdomains . Simultaneously, the tails of longer chains were squeezed to maintain the segment density in the microdomains at a constant value, leading to an increase in the domain size.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Simultaneously, the tails of longer chains were squeezed to maintain the segment density in the microdomains at a constant value, leading to an increase in the domain size. Furthermore, high polydispersities resulted in the shifting of order–order − and order–disorder , transition temperatures. Similar to the phase behavior of polydisperse block copolymers, in the polydisperse PS- b -P2VP/PS- g -PAA blends, we presume that shorter chains in PS- b -P2VP and PS- g -PAA would localize at the microdomain interface because shorter chains exhibit higher conformational entropy at the interface than longer chains.…”

Section: Results and Discussionmentioning

confidence: 99%

Chain Architecture and Hydrogen Bonding Induced Co-Ordering and Segregation of Block Copolymer/Graft Copolymer Blends

Wang

2019

Macromolecules

View full text Add to dashboard Cite

We investigated the effects of chain architecture and hydrogen-bonding interaction on the phase behavior of binary mixtures containing nearly symmetric polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer and highly asymmetric polystyrenegraf t-poly(acrylic acid) (PS-g-PAA) graft copolymer. When PS-g-PAA was added to PS-b-P2VP, hydrogen bonds between PAA and P2VP chains improved the miscibility of the copolymers and facilitated localization of PS-g-PAA at the PS-b-P2VP interface, which reduced the interfacial free energy of the blends. However, positioning PS-g-PAA with one PS main chain and two PAA grafted chains at the PS-b-P2VP interface increased the stretching free energy of PS-b-P2VP. Consequently, the interfacial coverage of PS-g-PAA reached saturation. Residual PS-g-PAA was segregated into the PS microdomains formed by PS-b-P2VP to regain translational entropy and reduce the stretching free energy. When the molecular weight ratio of PS-b-P2VP to PS-g-PAA (R) was smaller than 8, PS-g-PAA could not swell the PS microdomains formed by PS-b-P2VP. Therefore, the morphology of PS-b-P2VP/PS-g-PAA blends remained lamellar. By contrast, when R > 8, PS-g-PAA effectively swelled the PS microdomains formed by PS-b-P2VP. This behavior amplified the asymmetry effect caused by the branched-chain architecture of PS-g-PAA on altering the interfacial curvature of PS-b-P2VP. Consequently, the morphology of the blends transformed into a cylindrical structure.

show abstract

“…Furthermore, dissipative particle dynamics (DPD) simulations [24] have been used to construct the morphology diagrams for A 2 B copolymer melts and reasonable agreement with the SCFT predictions [7,23] has been established with the addition of new morphologies. Quite recently, a theory addressing the effects of polydispersity [25] on the microphase separation in A 2 B copolymers has been developed.…”

Section: Introductionmentioning

confidence: 99%

Morphology diagrams forA₂Bcopolymer melts: real-space self-consistent field theory

Kumar

Sides

et al. 2012

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

The standard Gaussian model for block copolymermelts M W Matsen -Stability of the fcc structure in block copolymer systems Makiko Nonomura -SCFT simulation and SANS study on spatial distribution of solvents in microphase separation induced by a differentiating non-solvent in a semi-dilute solution of an ultra-high-molecular-weight block copolymer K Ando, T Yamanaka, S Okamoto et al. Abstract. Morphology diagrams for A2B copolymer melts are constructed using real-space self-consistent field theory (SCFT). In particular, the effect of architectural asymmetry on the morphology diagram is studied. It is shown that asymmetry in the lengths of A arms in the A2B copolymer melts aids in the microphase separation. As a result, the disorder-order transition boundaries for the A2B copolymer melts are shown to shift downward in terms of χN, χ and N being the Flory's chi parameter and the total number of the Kuhn segments,respectively, in comparison with the A2B copolymers containing symmetric A arms. Furthermore, perforated lamellar (PL) and a micelle-like (M) microphase segregated morphologies are found to compete with the classical morphologies namely, lamellar, cylinders, spheres and gyroid. The PL morphology is found to be stable for A2B copolymers containing asymmetric A arms and M is found to be metastable for the parameter range explored in this work. IntroductionMicrophase separation in block copolymer melts [1,2,3,4,5,6,7] has motivated the scientific community over the last couple of decades. Delicate balance[3] of chain conformational entropy and repulsive interaction energy between unlike monomers allows block copolymers to readily self-assemble into a number of ordered morphologies. Typical morphologies [3,8,9] include lamellar, cylinder, sphere, gyroid and Fddd network phases, which have been proven to be equilibrium states.Experimentally, the balance of the energy and entropy can be tuned by a number of molecular characteristics such as molecular weight [3], chain architecture [10,11], conformational asymmetry [12,13], polydispersity [14,15,16,17,18] and temperature. A number of studies [1,2,3,4,5,6,7] have been done to elucidate the effects of molecular weight, polydispersity, conformational asymmetry and temperature on the mircophase separation in linear di-block copolymer melts. However, the effects of chain architecture are not that well established. On the computational side, this is primarily due to a large parameter space for the simulations and resulting large number of morphologies, which need to be compared in terms of their free-energy

show abstract

Microphase separation in polydisperse miktoarm star copolymers

Cited by 7 publications

References 44 publications

Effects of Randomly End-Linked Copolymer Network Parameters on the Formation of Disordered Cocontinuous Phases

Effects of Randomly End-Linked Copolymer Network Parameters on the Formation of Disordered Cocontinuous Phases

Chain Architecture and Hydrogen Bonding Induced Co-Ordering and Segregation of Block Copolymer/Graft Copolymer Blends

Morphology diagrams forA₂Bcopolymer melts: real-space self-consistent field theory

Contact Info

Product

Resources

About

Microphase separation in polydisperse miktoarm star copolymers

Cited by 7 publications

References 44 publications

Effects of Randomly End-Linked Copolymer Network Parameters on the Formation of Disordered Cocontinuous Phases

Effects of Randomly End-Linked Copolymer Network Parameters on the Formation of Disordered Cocontinuous Phases

Chain Architecture and Hydrogen Bonding Induced Co-Ordering and Segregation of Block Copolymer/Graft Copolymer Blends

Morphology diagrams forA2Bcopolymer melts: real-space self-consistent field theory

Contact Info

Product

Resources

About

Morphology diagrams forA₂Bcopolymer melts: real-space self-consistent field theory