Paper Number
SM27 

Session
Polymers Solutions, Melts, and Blends

Title
Predicting the plateau modulus from molecular parameters of conjugated polymers

Presentation Date and Time
October 12, 2021 (Tuesday) 5:00

Track / Room
Track 1 / Ballroom 5

Authors (Click on name to view author profile)

  1. Fenton, Abigail M. (The Pennsylvania State University, Chemical Engineering)
  2. Gomez, Enrique D. (The Pennsylvania State University, Chemical Engineering)
  3. Colby, Ralph H. (The Pennsylvania State University, Material Science and Engineering)

Author and Affiliation Lines (in printed abstract book)
Abigail M. Fenton1, Enrique D. Gomez1 and Ralph H. Colby2
1Chemical Engineering, The Pennsylvania State University, University Park, PA 16802; 2Material Science and Engineering, The Pennsylvania State University, University Park, PA 16802

Speaker / Presenter 
Fenton, Abigail M.

Keywords
polymer melts

Text of Abstract
The relationship between Kuhn length b, Kuhn monomer volume v0, and plateau modulus GN° initially proposed by Graessley and Edwards and experimentally investigated by Everaers, while well-studied for flexible and stiff polymers, has a large gap in experimental data between the flexible and stiff regimes. This gap prevents the validation of the crossover between flexible and stiff polymers and therefore, the prediction of mechanical properties from chain structure of any polymer in this region. Given the chain architecture, including a semiflexible backbone and side chains, conjugated polymers are an ideal class of material to study this cross-over region. Using small angle neutron scattering, oscillatory shear rheology, in-situ polarized optical rheology, along with the freely rotating chain model, we have shown that twelve polymers with aromatic backbones, including conjugated polymers, populate a large part of this gap. We also have shown that a few of these polymers exhibit nematic ordering, which explains a lower experimental GN° than predicted using Everaers’ plot, as nematic polymers have fewer entanglements than isotropic polymers. Nevertheless, when 50 ? above the nematic to isotropic transition, these polymers follow the proposed relationship between b, v0, and GN°.