Molecular sources of ratcheting in poly-dispersed polycarbonate

Molecular dynamics (MD) of polycarbonate is used to understand the molecular bases of ratcheting and sensitivity to variation in polymer chain lengths. We find that ratcheting is almost insensitive to molecular weight in mono-disperse systems, but not in poly-disperse systems. MD-to-continuum measures show that molecular motions of short chains in poly-dispersed systems are distinct from longer-sized chains, and, via easily detangling, moving, and relaxing, become compact even when the bulk expands. This indicates that short chains in poly-disperse systems play a central role in creating non-affine volume that accelerates ratcheting, while having no influence in short-chained mono-disperse systems.