## Abstract

A renormalized one-loop (ROL) theory developed in previous work [P. Grzywacz, J. Qin, and D. C. Morse, Phys. Rev E. 76, 061802 (2007)]10.1103/ PhysRevE.76.061802 is used to calculate corrections to the random phase approximation (RPA) for the structure factor S(q) in disordered diblock copolymer melts. Predictions are given for the peak intensity S(q ^{*}), peak position q^{*}, and single-chain statistics for symmetric and asymmetric copolymers as functions of X _{e}N, where X_{e} is an effective Flory-Huggins interaction parameter and N is the degree of polymerization. The ROL and Fredrickson-Helfand (FH) theories are found to yield asymptotically equivalent results for the dependence of the peak intensity S(q) upon X_{e}N for symmetric diblock copolymers in the limit of strong scattering, or large X_{e}N, but to yield qualitatively different predictions for symmetric copolymers far from the ODT and for asymmetric copolymers. The ROL theory predicts a suppression of S(q) and a decrease of q for large values of X_{e}N, relative to the RPA predictions, but an enhancement of S(q) and an increase in q for small X _{e}N. The decrease in q near the ODT is shown to be unrelated to any change in single-chain statistics, and to be a result of inter-molecular correlations. Conversely, the predicted increase in q at small values of X _{e}N is a direct result of non-Gaussian single-chain statistics.

Original language | English (US) |
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Article number | 084902 |

Journal | Journal of Chemical Physics |

Volume | 135 |

Issue number | 8 |

DOIs | |

State | Published - Aug 28 2011 |

### Bibliographical note

Funding Information:This work was supported by NSF grant DMR-097338. D.C.M. also gratefully acknowledges support in the form of a visiting professorship from the Academy of Sciences of the University of Göttingen.