Darin Q. Pike

Theoretically informed coarse grain simulations of polymeric systems

A Monte Carlo formalism for the study of polymeric melts is described. The model is particle-based, but the interaction is derived from a local density functional that appears in the field-based model. The method enables Monte Carlo simulations in the nVT, nPT, semigrandcanonical and Gibbs ensembles, and direct calculation of free energies. The approach is illustrated in the context of two examples. In the first, we consider the phase separation of a binary homopolymer blend and present results for the phase diagram and the critical point. In the second, we address the microphase separation of a symmetric diblock copolymer, examine the distribution of local stresses in lamellae, and determine the order-disorder transition temperature.

Theoretically informed coarse grain simulations of block copolymer melts: method and applications

A newly developed formalism is described, in which models that have been traditionally addressed using field-theoretic methods are solved by resorting to Monte Carlo simulations in arbitrary ensembles. In the context of block copolymer melts, the formalism starts from a standard, field-based Hamiltonian, but describes the polymeric chains explicitly, as collections of beads connected by springs, and incorporates the effects of fluctuations. The general applicability of the method is illustrated by discussing several examples from the recent literature, including the effect of fluctuations on the order–disorder transition of diblock copolymers, the morphology of linear triblock copolymers, the directed assembly of copolymer on nanopatterned substrates, and the hierarchical assembly of nanoparticle-copolymer mixtures.

Simulations of theoretically informed coarse grain models of polymeric systems

Simulations of theoretically informed coarse grain models, where the interaction energy is given by a functional of the local density, are discussed in the context of polymeric melts. Two different implementations are presented by addressing two examples. The first relies on a grid-based representation of non-bonded interactions and focuses on the concept of density multiplication in block copolymer lithography. Monte Carlo simulations are used in a high-throughput manner to explore the parameter space, and to identify morphologies amenable to lithographic fabrication. In the second example, which focuses on the order-disorder transition of block copolymers, the constraints imposed by a grid are removed, thereby enabling simulations in arbitrary ensembles and direct calculation of local stresses and free energies.

Monte-Carlo simulation of ternary blends of block copolymers and homopolymers.

We perform a theoretically informed coarse grain Monte-Carlo simulation in the nPT-ensemble and the Gibbs ensemble on symmetric ternary mixtures of AB-diblock copolymers with the corresponding homopolymers. We study the lamellar period by varying the length and amount of homopolymers. The homopolymer distribution within the lamellar morphology is determined as is the maximum amount of homopolymer within the lamellae. Gibbs ensemble simulations are used to locate the three-phase coexistence between two homopolymer-rich phases and a lamellar phase.

Integration of Block-Copolymer with Nano-Imprint Lithography: Pushing the Boundaries of Emerging Nano-Patterning Technology.

The extreme nanoscale features prescribed by the International Technology Roadmap for Semiconductors (ITRS, e.g., 11nm half-pitch for dense patterns and 4.5nm critical dimensions by 2022) require infrastructure-heavy extreme ultraviolet (EUV) and/or