Dissociation effect of non-covalent bond for morphological behavior of triblock copolymers: a dissipative particle dynamics study

The nanophase separation structure produced by block polymers is used for highly functional materials and has been studied for 50 years. In recent years, researchers have shown interest in introducing non-covalent bonds, such as hydrogen bonds and metal–ligand bonds, to polymers. The non-covalent bond dissociates or recombines in response to physical conditions, including temperature and concentration. The non-covalent bond freely controls the phase separation structure, namely, the physical properties of the polymer material. However, various interactions are involved in the formation process, for example, polymer–polymer, polymer–solvent, bonding and bending in the polymer. To control the self-assembled structure, it is necessary to understand the influence of the non-covalent bond at the molecular level. In this study, we investigated the effect of the non-covalent bond on a stage of phase separation immediately after dissociation (early-stage) of self-assembled morphologies by introducing the binding site to the triblock polymers. Various stable morphologies, including lamellar, lamellar with a grain boundary, and pre-lamellar, were observed by changing the positions of the non-covalent bond, their dissociation ratio, and the initial configurations. Moreover, we calculated the radial distribution function and static structure factor to identify the structural features. The results suggested that the early-stage of self-assembled morphology in polymer melt could be controlled by the position of the non-covalent bond and its dissociation ratio.