Glassy dynamics of crystallite formation: The role of covalent bonds

TL;DR

This study uses molecular dynamics simulations to compare the collapse and crystallization behaviors of polymers with covalent bonds to colloidal systems, revealing how chain connectivity influences nonequilibrium dynamics and structural relaxation.

Contribution

It demonstrates that while static and qualitative nonequilibrium features are similar, quantitative differences in rearrangements are driven by chain connectivity, advancing understanding of polymer and protein relaxation.

Findings

Polymer and colloid static properties align when scaled by T_{cryst}

Qualitative nonequilibrium relaxation features are similar in polymers and colloids

Chain connectivity causes quantitative differences in rearrangements

Abstract

We examine nonequilibrium features of collapse behavior in model polymers with competing crystallization and glass transitions using extensive molecular dynamics simulations. By comparing to "colloidal" systems with no covalent bonds but the same non-bonded interactions, we find three principal results: (i) Tangent-sphere polymers and colloids, in the equilibrium-crystallite phase, have nearly identical static properties when the temperature T is scaled by the crystallization temperature T_{cryst}; (ii) Qualitative features of nonequilibrium relaxation below T_{cryst}, measured by the evolution of local structural properties (such as the number of contacts) toward equilibrium crystallites, are the same for polymers and colloids; and (iii) Significant quantitative differences in rearrangements in polymeric and colloidal crystallites, in both far-from equilibrium and near-equilibrium systems, can be understood in terms of chain connectivity. These results have important implications for understanding slow relaxation processes in collapsed polymers, partially folded, misfolded, and intrinsically disordered proteins.