Effect of chemical design of grafted polymers on the self-assembled morphology of polymer-tethered nanoparticles in nanotubes.

There is a clear relationship between the self-assembling architecture of nanoparticles (NPs) and their physical properties, and they are currently used in a variety of applications, including optical sensors. Polymer-tethered NPs, which are created by grafting polymers onto NPs to control the self-assembly of NPs, have attracted considerable attention. Recent synthetic techniques have made it possible to synthesize a wide variety of polymers and thereby create NPs with many types of surfaces. However, self-assembled structures have not been systematically classified because of the large number of tuning parameters such as the polymer length and graft density. In this study, by using coarse-grained molecular simulation, we investigated the changes in the self-assembled structure of polymer-tethered NP solutions confined in nanotubes due to the chemical properties of polymers. Three types of tethered polymer NP models were examined: homo hydrophilic, diblock hydrophilic-hydrophobic (HI-HO), and diblock hydrophobic-hydrophilic. Under strong confinement, the NPs were dispersed in single file at low axial pressure. As the pressure increased, multilayered lamellar was observed in the HI-HO model. In contrast, under weak confinement, the difference in the pressure at which the phases emerge, depending on the model, was significant. By changing the chemical properties of the grafted polymer, the thermodynamic conditions (the axial pressure in this study) under which the phases appear is altered, although the coordination of NPs remains almost unchanged. Our simulation offers a theoretical guide for controlling the morphologies of self-assembled polymer-tethered NPs, a novel system that may find applications in nanooptical devices or for nanopatterning.