TY - JOUR
T1 - Absence of the nematic phase in symmetric diblock copolymers
AU - Morse, David C.
AU - Milner, Scott T.
PY - 1993/1/1
Y1 - 1993/1/1
N2 - We examine the possibility of nematic order in systems described by the Brazovskii model [Sov. Phys. JETP 41, 85 (1975)] of the isotropic-lamellar phase transition, including symmetric diblock copolymer melts and bilayer-forming surfactant systems. We introduce a nematic order parameter and look for states that break rotational symmetry that is, which have a well-defined direction for interfacial normals, but no phase coherence between interfaces. We find an isotropic-nematic phase transition, but it is always precluded by an isotropic-lamellar phase transition occurring at higher temperature. We show that the lamellar phase is stable to dislocation-mediated melting to a nematic phase in the limit of long copolymer chains, even though the isotropic-lamellar phase transition becomes second order in this limit.
AB - We examine the possibility of nematic order in systems described by the Brazovskii model [Sov. Phys. JETP 41, 85 (1975)] of the isotropic-lamellar phase transition, including symmetric diblock copolymer melts and bilayer-forming surfactant systems. We introduce a nematic order parameter and look for states that break rotational symmetry that is, which have a well-defined direction for interfacial normals, but no phase coherence between interfaces. We find an isotropic-nematic phase transition, but it is always precluded by an isotropic-lamellar phase transition occurring at higher temperature. We show that the lamellar phase is stable to dislocation-mediated melting to a nematic phase in the limit of long copolymer chains, even though the isotropic-lamellar phase transition becomes second order in this limit.
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U2 - 10.1103/PhysRevE.47.1119
DO - 10.1103/PhysRevE.47.1119
M3 - Article
AN - SCOPUS:0000518219
VL - 47
SP - 1119
EP - 1125
JO - Physical Review E - Statistical, Nonlinear, and Soft Matter Physics
JF - Physical Review E - Statistical, Nonlinear, and Soft Matter Physics
SN - 1539-3755
IS - 2
ER -