Molecular Dynamics Simulations of Poly(3-hexylthiophenes) in Dilute Solutions

Abstract

University of Washington Abstract Molecular Dynamics Simulations of Poly(3-hexylthiophenes) in Dilute Solutions Stephanie M. Hoffmann Chair of the Supervisory Committee: Professor Jim Pfaendtner, Ph.D. Chemical Engineering Conjugated polymers hold exciting potential in the field of organic electronics. As compared with traditional devices, polymer-based electronic devices are cheaper, lighter, and more easily processed. Molecular dynamics (MD) simulation is a useful tool for the study of these polymers because it allows us to probe structural properties at a length scale unobtainable by current experimental techniques. Using MD simulations, poly(3-hexylthiophene) (P3HT) was studied in multiple solvents to probe the effect of solvation on structural properties. Additionally, poly(3-alkylthiophenes) (P3ATs) with side chains varying from two to twelve carbons in length were studied to determine the effect side chain length on these same properties. P3HT was found to have more flexibility in chlorinated solvents, chloroform and dichlorobenzene, than in the other solvents studied. Analysis of the pairwise distribution functions suggests these differences may arise due to the differences in the polymer-solvent interactions. In the case of varying side chain lengths, a counterintuitive inverse proportionality relationship was found between persistence lengths and conjugation lengths. A variety of analyses were unable to illuminate the underlying reason for this inverse relationship.