Topological constraint of ring fillers on the lamellar forming ABA-type tri-block copolymers using coarse-grained molecular dynamics simulations

Abstract

Coarse-grained molecular dynamics simulations were performed under the restriction of chain-crossing prohibition to investigate the effect of topological constraints by ring fillers on the lamellar domain spacing D of ABA tri-block copolymers (BCPs), where A domain is hard, and B domain is soft. Here, we introduced an effective bridge by linking a B component ring filler between two U-shaped loop configurations of the ABA tri-BCPs. For a large fraction (f_add) of the additional ring fillers, we found that D for the linked ring cases became much smaller than that for the unlinked ring cases. It was also confirmed that the reduction effect was greater for smaller sizes of the linked rings. Moreover, we found that normalized domain spacing (D/N_total) was proportional to number of links by ring fillers, where N_total denotes the total number of beads in the system under the periodic boundary conditions. For small f_add, void growth and stretching of fibril-like ring fillers were observed in the soft B domain, whereas for large f_add, temporal void growth in the soft B domain was observed before total fracture in the hard A domain. A bonded ring complex was also considered as an alternative to a simple ring, but it was found that there was little difference. This work will promote syntheses of a linked ring filler with deuterated polymers and observations of the behavior of single-molecules.