Abstract
Micelles formed by ionizable co-polymers are governed by both van der Waals and electrostatic forces. Slight tweaking of the solvent characteristics often drives large structural transformations. Here, the effects of modulating the electrostatic characteristics of solvents on polymeric assemblies formed by a co-polymer with ABCBA topology and an ionizable polystyrene sulfonate center (C) tethered to polyethylene propylene (B) end-capped by t-butyl styrene (A) are probed by small angle neutron scattering in cyclohexane/propanol solutions. With increasing propanol fraction, the spherical core-shell micelles, with the ionic block in their core, elongate and transition into large “swarms.” Surprisingly, as propanol becomes the major component of the solvent, reentrant spherical assemblies with a smaller polystyrene sulfonate core are formed. The propanol partitions across the interface between the core and the corona, affecting the polymer distribution in the corona and the core-corona boundary’s curvature, resulting in morphing of the shape of assemblies.
| Original language | English |
|---|---|
| Article number | 214904 |
| Journal | Journal of Chemical Physics |
| Volume | 162 |
| Issue number | 21 |
| DOIs | |
| State | Published - Jun 7 2025 |
Funding
This work was supported by the NSF (Grant No. DMR-1905407). The SANS measurements conducted using the GP-SANS at ORNL’s high-flux isotope reactor (HFIR) neutron source were sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. Travel to Oak Ridge National Laboratory to carry out this work was supported by a Travel Fellowship from the DOE-EPSCoR Grant to the University of Tennessee (Grant No. DE-FG02-08ER46528). The numerical simulations were performed under the supervision of Dr. Gary S. Grest, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science at Sandia National Laboratories (Contract No. DE-NA-0003525) and at the Palmetto cluster, which is part of the supercomputer facility at Clemson university. The authors would also like to thank Dr. Dipak Aryal for valuable guidance on the numerical simulations.