Abstract
The self-assembly of multiblock copolymers in solutions is controlled by a delicate balance between inherent phase segregation due to incompatibility of the blocks and the interaction of the individual blocks with the solvent. The current study elucidates the association of pentablock copolymers in a mixture of selective solvents which are good for the hydrophobic segments and poor for the hydrophilic blocks using small angle neutron scattering (SANS). The pentablock consists of a center block of randomly sulfonated polystyrene, designed for transport, tethered to poly-ethylene-r-propylene and end-capped by poly-t-butyl styrene, for mechanical stability. We find that the pentablock forms ellipsoidal core-shell micelles with the sulfonated polystyrene in the core and Gaussian decaying chains of swollen poly-ethylene-r-propylene and poly-t-butyl styrene tertiary in the corona. With increasing solution concentration, the size of the micelle, the thickness of the corona, and the aggregation number increase, while the solvent fraction in the core decreases. In dilute solution the micelle increases in size as the temperature is increased, however, temperature effects dissipate with increasing solution concentration.
| Original language | English |
|---|---|
| Article number | 184903 |
| Journal | Journal of Chemical Physics |
| Volume | 145 |
| Issue number | 18 |
| DOIs | |
| State | Published - Nov 14 2016 |
Funding
This work was supported by the U.S. Department of Energy under Contract No. DE-SC007908. The SANS measurements conducted using the EQ-SANS at ORNLs Spallation Neutron Source and GP-SANS at ORNLs High Flux Isotope Reactor 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. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. Department of Energy and Office of Basic Energy Sciences user facility. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energys National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.