Ring and Linear Copolymer Blends under Confinement

Abstract

The behavior of dense mixtures of two topologically different diblock-copolymer (CP) chains, viz., linear(L)-CP and ring(R)-CP of same molecular weight which forms lamellae is studied under confinement by two non-selective substrates. The effect of varying interaction strength between L-CP and R-CP, from purely repulsive (demixed state) to weakly attractive (mixed state), on the morphology, domain size, chain conformations and distribution of chains in the film are investigated. In the demixed state, collective structure factor S(q) shows a split of the predominant peak indicating the presence of two dominant length scales. While there is only one predominant peak in the mixed state, and hence a lamellar structure with single domain size. We show that the peak position q * of S(q) can be varied with the L/R interaction strength and thus allow one to control domain size by tuning L/R interaction strength without altering the chain size. We further characterize the chain size and illustrate that this domain size variation is a consequence of the variation in the size of L-CPs. Furthermore, results on the average instantaneous shape of R/L-CP reveal that their shapes are very different both in bulk and near the substrate, and R-CP assumes an oblate shape near the substrate. This shape/size difference leads to the segregation of R-CPs near the polymer-substrate interface and hence a relatively higher density of R-CPs at the interface.

Phase and Order Behavior of Charged Asymmetric Diblock‐Copolymer Melts in Bulk

“…In this section, we study how the domain size of charged DBCs changes when the charge fraction of A‐block is varied. Here, we employ box counting method [ 27,28 ] to compute the domain sizes. In this approach, we calculate the concentration of A‐monomers ρ A in a sphere of radius r drawn at a random position within our simulation box.…”

“…In this section, we study how the domain size of charged DBCs changes when the charge fraction of A-block is varied. Here, we employ box counting method [27,28] to compute the domain sizes.…”

Effect of Topology on the Collapse Transition and the Instantaneous Shape of a Model Heteropolymer

“…In this regard, ring or cyclic polymer, a topologically constrained chain made by closing the chain ends of a linear polymer and thus no chain ends, is relevant not only in physics, but also in biology as a model system for chromatin folding and existence of chromosome territories. [4][5][6][7] DOI: 10.1002/mats. 202200074 The existance of circular topology in biopolymer, e.g., in DNA of bacteriophage, ϕX174, was observed as early as 1964.…”

“…In this regard, ring or cyclic polymer, a topologically constrained chain made by closing the chain ends of a linear polymer and thus no chain ends, is relevant not only in physics, but also in biology as a model system for chromatin folding and existence of chromosome territories. [ 4–7 ]…”