Phase separation in polydisperse rod–coil block copolymers

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

doi:10.1016/j.physa.2013.08.032

Cited by 5 publications

(5 citation statements)

References 67 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In weak segregation some results of the phase behaviour found in Ref. [1] till [18] are observed in experiments, see also Ref. [41] till [45].…”

Section: Introductionmentioning

confidence: 58%

“…s respectively denote the block length of the j-th block and the persistence length of the i-th block in a chain of type s which consists of N b s blocks. The function θ(...) in (18) between the square brackets is the Heaviside step function. The first term in (17) containing the orientation vectors of the endpoints of the chains and the particular choice of the coefficients in the second term of (17) ensure homogeneity of the chains and Porod-Kratky like behavior in an averaged sense, i.e.…”

Section: The Modelmentioning

confidence: 99%

“…In Ref. [1] till [18] the phase behaviour is described by the weak segregation theory which is only valid just below to the critical temperature. Further away from the phase transition at much smaller temperatures the phase structure becomes more markedly.…”

Section: Introductionmentioning

confidence: 99%

“…In Ref. [14] till [18] the effect of polydispersity is investigated for different kinds of block copolymers, but the work of Ref. [5] till [13] is restricted to monodisperse systems in the framework of the weak segregation limit.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

General weak segregation theory with an application to monodisperse semi-flexible diblock copolymers

Jager¹,

Briels²,

Slot³

2022

Preprint

View full text Add to dashboard Cite

A general theory has been developed for a polydisperse semi-flexible multi-block copolymer melt. Using the Bawendi-Freed approach to model semi-flexible chains an expression for the Landau free energy is derived in the weak segregation regime which includes the density and orientation order-parameters. The orientation order-parameter is described in the smectic phase and in more complicated structures such as the hexagonal phase. The Landau free energy contains contributions of two kinds of interactions. The first kind is the Flory-Huggins interaction which describes the incompatibility of chemically different blocks and may induce microphase separation. The second kind is the Maier-Saupe interaction which may induce nematic ordening. In the framework of the weak segragation limit the Landau theory allows to predict phase structures in the melt as a function of the composition, persistence length and the strength of the Flory-Huggins and Maier-Saupe interaction. The general theory is applied to a simple system of monodisperse semi-flexible diblock copolymers. In several phase diagrams a number of possible phase structures is predicted such as the bcc, hexagonal, smectic-A, smectic-C and nematic phase. The influence of the Maier-Saupe interaction on the microphase structure is thoroughly discussed.

show abstract

“…In weak segregation some results of the phase behaviour found in Ref. [1] till [18] are observed in experiments, see also Ref. [41] till [45].…”

Section: Introductionmentioning

confidence: 58%

Section: The Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

General weak segregation theory with an application to monodisperse semi-flexible diblock copolymers

Jager¹,

Briels²,

Slot³

2022

Preprint

View full text Add to dashboard Cite

show abstract

“…One notes, however, that this approach is valid in the vicinity of the transition into the isotropic disordered phase. The equilibrium monomer density also contains only one Fourier harmonic and hence it can be used in the case of weak segregation only [ 14 ]. Another approach employs the self-consistent field theory (SCFT) which has been successfully used for the description of coil-coil and rod-coil diblock copolymers [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

Liquid-Crystal Ordering and Microphase Separation in the Lamellar Phase of Rod-Coil-Rod Triblock Copolymers. Molecular Theory and Computer Simulations

et al. 2021

View full text Add to dashboard Cite

A molecular model of the orientationally ordered lamellar phase exhibited by asymmetric rod-coil-rod triblock copolymers has been developed using the density-functional approach and generalizing the molecular-statistical theory of rod-coil diblock copolymers. An approximate expression for the free energy of the lamellar phase has been obtained in terms of the direct correlation functions of the system, the Flory-Huggins parameter and the Maier-Saupe orientational interaction potential between rods. A detailed derivation of several rod-rod and rod-coil density-density correlation functions required to evaluate the free energy is presented. The orientational and translational order parameters of rod and coil segments depending on the temperature and triblock asymmetry have been calculated numerically by direct minimization of the free energy. Different structure and ordering of the lamellar phase at high and low values of the triblock asymmetry is revealed and analyzed in detail. Asymmetric rod-coil-rod triblock copolymers have been simulated using the method of dissipative particle dynamics in the broad range of the Flory-Huggins parameter and for several values of the triblock asymmetry. It has been found that the lamellar phase appears to be the most stable one at strong segregation. The density distribution of the coil segments and the segments of the two different rods have been determined for different values of the segregation strength. The simulations confirm the existence of a weakly ordered lamellar phase predicted by the density-functional theory, in which the short rods separate from the long ones and are characterized by weak positional ordering.

show abstract

Microphase separation in polydisperse rod-rod diblock copolymer melt

Aliev

Kuzminyh

2015

The Journal of Chemical Physics

View full text Add to dashboard Cite

The stability limits of the isotropic state of melt of rod-rod AB polydisperse diblock copolymer have been studied within weak segregation theory. The number of units in A block is assumed to be a random variable distributed by the Schulz-Zimm distribution. Inspection of the spinodal curves shows that the copolymer melt with polydisperse rigid blocks is less stable with respect to formation of the nematic and microphase separated states than the monodisperse melt. The values of ratios between strengths of isotropic and anisotropic interactions in the system strongly influences the forms of isotropic-nematic boundary curves.

show abstract

Phase separation in polydisperse rod–coil block copolymers

Cited by 5 publications

References 67 publications

General weak segregation theory with an application to monodisperse semi-flexible diblock copolymers

General weak segregation theory with an application to monodisperse semi-flexible diblock copolymers

Liquid-Crystal Ordering and Microphase Separation in the Lamellar Phase of Rod-Coil-Rod Triblock Copolymers. Molecular Theory and Computer Simulations

Microphase separation in polydisperse rod-rod diblock copolymer melt

Contact Info

Product

Resources

About