Calibration of a lattice model for high-molecular-weight block copolymer melts

Abstract

The Morse calibration is applied to a lattice model designed for efficient simulations of two-component polymer melts of high molecular weight. The model allows multiple occupancy per site, which results in high invariant polymerization indices, and interactions are limited to monomers within the same site, which enhances the computational speed. The calibration maps the interaction parameter of the lattice model, α, onto the Flory-Huggins χ parameter of the standard Gaussian-chain model, by matching the disordered-state structure function, S(k), of symmetric diblock copolymers to renormalized one-loop predictions. The quantitative accuracy of the calibration is tested by comparing the order-disorder transition of symmetric diblock copolymer melts to the universal prediction obtained from previous simulations. The model is then used to confirm the universality of fluctuation corrections to the critical point of symmetric binary homopolymer blends.

Instability of the Microemulsion Channel in Block Copolymer-Homopolymer Blends

“…The effect of fluctuations is not as extreme as suggested by the experiments. There is a small shift in the Scott line consistent with the prediction for binary homopolymer melts [43,44,52], and a considerably larger shift in the DIS-to-LAM transition similar to that predicted for neat diblocks [36,42,53]. The three-phase coexistence of the SCFT phase diagram still remains, but the DIS-to-LAM line intersects it part way down on account of its larger shift.…”

Computationally Efficient Field-Theoretic Simulations for Block Copolymer Melts

“…A convenient feature of L-FTS are their similarity to SCFT calculations, on account of the fact that they rely on the same statistical mechanics of non-interacting polymers. Although conventional particle-based simulations can already handle diblock copolymer melts over the full experimental range ofN , 7,10,39 this is not generally the case for more complicated systems. On the other hand, as explicitly demonstrated in previous studies, field-theoretic simulations can be readily extended to elaborate block copolymers architectures 40,41 and innovative ensembles for dealing with blends.…”

Field-Theoretic Simulations for Block Copolymer Melts Using the Partial Saddle-Point Approximation

“…The earliest treatment by Fredrickson and Helfand [ 24 ] predicted a shift of , where is the invariant polymerization index. Particle-based simulations of different models [ 8 , 9 , 10 , 11 ] have since provided the more accurate prediction …”

“…Consequently, they can all be mapped onto the standard Gaussian chain model (GCM) [ 5 ], which is a minimal model that treats block copolymer systems as incompressible melts of thin elastic threads that interact by pairwise contact forces. At present, the most accurate method of performing the mapping is the Morse calibration [ 4 , 6 ], which has been well demonstrated for experiments [ 7 ] and particle-based simulations [ 8 , 9 , 10 , 11 , 12 ], as well as field-theoretic simulations [ 13 ].…”