Determination of the interaction parameter and topological scaling features of symmetric star polymers in dilute solution.
Star polymers provide model architectures to understand the dynamic and rheological effects of chain confinement for a range of complex topological structures like branched polymers, colloids, and micelles. It is important to describe the structure of such macromolecular topologies using small-angle neutron and x-ray scattering to facilitate understanding of their structure-property relationships. Modeling of scattering from linear, Gaussian polymers, such as in the melt, has applied the random phase approximation using the Debye polymer scattering function. The Flory-Huggins interaction parameter can be obtained using neutron scattering by this method. Gaussian scaling no longer applies for more complicated chain topologies or when chains are in good solvents. For symmetric star polymers, chain scaling can differ from ν=0.5(d(f)=2) due to excluded volume, steric interaction between arms, and enhanced density due to branching. Further, correlation between arms in a symmetric star leads to an interference term in the scattering function first described by Benoit for Gaussian chains. In this work, a scattering function is derived which accounts for interarm correlations in symmetric star polymers as well as the polymer-solvent interaction parameter for chains of arbitrary scaling dimension using a hybrid Unified scattering function. The approach is demonstrated for linear, four-arm and eight-arm polyisoprene stars in deuterated p-xylene.
Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN-37831, USA.
Durgesh K
DK
Rai
Materials Science and Engineering, University of Cincinnati, Cincinnati, OH-45221, USA.
Gregory
G
Beaucage
Department of Chemistry, University of Athens, Panepistimiopolis, Zografou, 15771, Athens, Greece.|Division of Physical Sciences and Engineering, KAUST Catalysis Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
Kedar
K
Ratkanthwar
Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
Peter
P
Beaucage
Procter & Gamble, 1 P&G Plaza, Cincinnati, OH-45202, USA.
Ramnath
R
Ramachandran
Department of Chemistry, University of Athens, Panepistimiopolis, Zografou, 15771, Athens, Greece.|Division of Physical Sciences and Engineering, KAUST Catalysis Center, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
Nikos
N
Hadjichristidis
D033363:Neutron Diffraction; D011108:Polymers / Q000737:chemistry*; D053838:Scattering, Small Angle; D012996:Solutions / Q000737:chemistry*; D014961:X-Ray Diffraction; D014992:Xylenes / Q000737:chemistry
D011108:Polymers; D012996:Solutions; D014992:Xylenes