Abstract
The effects of polymer chain topology on the order-disorder transition of symmetric AB diblock copolymer melts are studied using coarse-grained molecular dynamics simulations. Specifically, we compared chain conformations near the lamellar-disordered transition in melts of symmetric (i.e., 50-50) AB diblock copolymers of linear chains, rings, and trefoil knots at the same chain lengths. The order (lamellar)-disorder transition temperature and the domain sizes both shifted to lower values with the introduction of topological constraints, leading to the following sequence: linear chains > rings > trefoil knots. Investigation of the polymer chain conformations in terms of their radii of gyration, their writhe values (a measure for the degree of intertwining of a chain around itself), and their Jones polynomials (a method to measure entanglement of curves) showed that linear chains and rings remained stretched, while knots were stretched and tightened in disordered melts close to the lamellar-disorder transition. This work highlights chain topology as an important factor in affecting microphase separation in block copolymers.
| Original language | English |
|---|---|
| Pages (from-to) | 7492-7499 |
| Number of pages | 8 |
| Journal | Macromolecules |
| Volume | 54 |
| Issue number | 16 |
| DOIs | |
| State | Published - Aug 24 2021 |
Funding
This work was performed at the Center for Nanophase Materials Sciences, a US DOE Office of Science User Facility. This research used resources of the Oak Ridge Leadership Computing Facility (OLCF) and of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC05-00OR22725. T.H. and E.P. thank the support of NSF DMS #1913180.