Phase segregation in gradient copolymer melts

Michelle D. Lefebvre; Monica Olvera De La Cruz; Kenneth R. Shull

doi:10.1021/ma035141a

Phase segregation in gradient copolymer melts

Michelle D. Lefebvre, Monica Olvera De La Cruz, Kenneth R. Shull^*

^*Corresponding author for this work

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

108 Scopus citations

Abstract

Local segregation in melts of copolymers with composition gradients along their backbones is analyzed. The transition to a lamellar periodic structure as the effective degree of incompatibility χN increases is studied for symmetric copolymers with various composition gradients. A numerical self-consistent mean-field (SCMF) technique is used to characterize the ordered lamellar state in the weak and strong segregation regimes, and the random phase approximation (RPA) is used to calculate the scattering function analytically and find the location of the critical order-disorder transition for each melt. The critical point increases from (χN)_c = 10.495 for block copolymers to (χN)_c = 29.25 for a fully tapered linear gradient copolymer. For broad composition gradients the equilibrium lamellar repeat length is shorter for a given value of χN, and the unit cell composition profile is more sinusoidal. The dependence of the equilibrium repeat distance on χN is nearly universal when renormalized by the critical point of each copolymer.

Original language	English (US)
Pages (from-to)	1118-1123
Number of pages	6
Journal	Macromolecules
Volume	37
Issue number	3
DOIs	https://doi.org/10.1021/ma035141a
State	Published - Feb 10 2004

ASJC Scopus subject areas

Organic Chemistry
Polymers and Plastics
Inorganic Chemistry
Materials Chemistry

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abstract = "Local segregation in melts of copolymers with composition gradients along their backbones is analyzed. The transition to a lamellar periodic structure as the effective degree of incompatibility χN increases is studied for symmetric copolymers with various composition gradients. A numerical self-consistent mean-field (SCMF) technique is used to characterize the ordered lamellar state in the weak and strong segregation regimes, and the random phase approximation (RPA) is used to calculate the scattering function analytically and find the location of the critical order-disorder transition for each melt. The critical point increases from (χN)c = 10.495 for block copolymers to (χN)c = 29.25 for a fully tapered linear gradient copolymer. For broad composition gradients the equilibrium lamellar repeat length is shorter for a given value of χN, and the unit cell composition profile is more sinusoidal. The dependence of the equilibrium repeat distance on χN is nearly universal when renormalized by the critical point of each copolymer.",

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T1 - Phase segregation in gradient copolymer melts

AU - Lefebvre, Michelle D.

AU - Olvera De La Cruz, Monica

AU - Shull, Kenneth R.

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N2 - Local segregation in melts of copolymers with composition gradients along their backbones is analyzed. The transition to a lamellar periodic structure as the effective degree of incompatibility χN increases is studied for symmetric copolymers with various composition gradients. A numerical self-consistent mean-field (SCMF) technique is used to characterize the ordered lamellar state in the weak and strong segregation regimes, and the random phase approximation (RPA) is used to calculate the scattering function analytically and find the location of the critical order-disorder transition for each melt. The critical point increases from (χN)c = 10.495 for block copolymers to (χN)c = 29.25 for a fully tapered linear gradient copolymer. For broad composition gradients the equilibrium lamellar repeat length is shorter for a given value of χN, and the unit cell composition profile is more sinusoidal. The dependence of the equilibrium repeat distance on χN is nearly universal when renormalized by the critical point of each copolymer.

AB - Local segregation in melts of copolymers with composition gradients along their backbones is analyzed. The transition to a lamellar periodic structure as the effective degree of incompatibility χN increases is studied for symmetric copolymers with various composition gradients. A numerical self-consistent mean-field (SCMF) technique is used to characterize the ordered lamellar state in the weak and strong segregation regimes, and the random phase approximation (RPA) is used to calculate the scattering function analytically and find the location of the critical order-disorder transition for each melt. The critical point increases from (χN)c = 10.495 for block copolymers to (χN)c = 29.25 for a fully tapered linear gradient copolymer. For broad composition gradients the equilibrium lamellar repeat length is shorter for a given value of χN, and the unit cell composition profile is more sinusoidal. The dependence of the equilibrium repeat distance on χN is nearly universal when renormalized by the critical point of each copolymer.

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Phase segregation in gradient copolymer melts

Abstract

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