Threading of Ring Poly(ethylene oxide) Molecules by Linear Chains in the Melt

Area of Science:

• Polymer Physics
• Materials Science
• Computational Chemistry

Background:

• Understanding the topological dynamics of polymers is crucial for predicting material properties.
• Ring-linear polymer blends present complex topological interactions affecting chain mobility.

Purpose of the Study:

• To investigate the topological entanglement and dynamics of ring-linear poly(ethylene oxide) (PEO) blends.
• To quantify the impact of linear PEO chains on the dynamics of cyclic PEO.

Main Methods:

• Atomistic molecular dynamics simulations of ring-linear PEO melts.
• Topological reduction to primitive paths and geometric analysis using vector calculus.
• Systematic variation of molecular weight and composition in PEO blends.

Main Results:

• Significant cyclic threading of linear chains through ring PEO observed, especially for molecular weights > 10044 g/mol.
• Threading events were found to be long-lived, with linear chains taking substantially longer to pass through rings than rings relax in their own melts.
• Linear chains dramatically obstruct ring mobility, even at low concentrations, leading to heterogeneous dynamics.

Conclusions:

• The dynamics of ring-linear polymer blends are highly heterogeneous due to persistent topological entanglements.
• Linear polymer chains act as significant obstacles to ring polymer diffusion and relaxation.
• These findings have implications for the design and processing of polymer materials containing cyclic components.