Self-Assembly of Symmetric Diblock Copolymers in Planar Slits with and without Nanopatterns: Insight from Dissipative Particle Dynamics Simulations

Abstract

We present a dissipative particle dynamics simulation study on the formation of nanostructures of symmetric diblock copolymers confined between planar surfaces with and without nanopatterns. The nanopatterned surface is mimicked by alternating portions of the surface that interact differently with the diblock copolymers. The formation of the diblock-copolymer nanostructures confined between the planar surfaces is investigated and characterized by varying the separation width and the strength of the interaction between the surfaces and the diblock copolymers. For surfaces with nanopatterns, we also vary both the mutual area and location of the nanopatterns, where we consider nanopatterns on the opposing surfaces that are vertically (a) aligned, (b) staggered, and (c) partially staggered. In the case of planar slits without nanopatterns, we observe the formation of perpendicular and parallel lamellar phases with different numbers of lamellae. In addition, the symmetric diblock copolymers self-assemble into adsorbed layer and adsorbed layer-parallel lamellar phases and a mixed lamellar phase when the opposing surfaces of the planar slits are modeled by different types of wall beads. In the case of nanopatterned planar slits, we observe novel nanostructures and attempt to rationalize the diblock copolymer self-assembly on the basis of the behavior that we observed in the planar slits without nanopatterns. In particular, we investigate the applicability of predicting the structures formed in the nanopatterned slits by a superposition of the observed structures in slits without nanopatterns.

Dissipative particle dynamics for directed self-assembly of block copolymers

“…The setup for DPD in this work is modified from the previously reported DPD method 34 . In particular, each linear diblock copolymer is represented by 20 beads (compared to 10 beads for previous studies) [34][35][36] . Each bead can be of A and B types, as shown in Figure 1(a).…”

Scaling behaviour of different polymer models in dissipative particle dynamics of unentangled melts

“…The reduced value of the maximum repulsion a* ; a ij r c =ðk B TÞ in Equation (10) was set to 25 [3]. For the harmonic spring (11), values of K * H ; K H =ðk B TÞ were varied from 2 to 10. For the FENE spring (12), we set r * max ; r max =r c ¼ 4, which is a typical value used in the previous DPD studies, [19,31,32] and we used values of K * F ;…”

“…DPD was introduced by Hoogerbrugge and Koelman in 1992 [1,2], and soon after refined for polymers by Groot and Warren [3]. Presently for polymer systems, DPD has been used to simulate a variety of problems such as the static and dynamic properties of polymer melts, [4] polymer solutions, [5,6] self-assembly of block copolymers in bulk, [7 -9] under shear [10] and in confinement, [11,12] self-assembly of nanoparticle mixtures in diblock copolymers, [13 -15] polymer brushes, [16 -18] pressuredriven flow of polymer solutions in nanoconfinement [19] and polymer translocation through a nanopore, [20] as well as many others.…”

Investigation of interfacial and structural properties of CTAB at the oil/water interface using dissipative particle dynamics simulations

“…An alternative approach is to simulate the oil/water/surfactant system at a mesoscopic level. Dissipative particle dynamics (DPD) is a technique that has been developed to simulate fluids at a mesoscopic level [31][32][33]. Compared with usual dynamics simulations, for example all-atom simulation, the major advantage of DPD is its soft interactions [34,35].…”