Intermolecular structural correlations in model globular and unconcatenated ring polymer liquids

Area of Science:

• Polymer Physics
• Soft Matter Physics
• Statistical Mechanics

Background:

• Dense liquids of interpenetrating ring polymers and globule models present complex thermodynamic and structural challenges.
• Understanding the behavior of these systems is crucial for applications in soft nanotechnology and materials science.

Purpose of the Study:

• To develop a segment-level theory for the thermodynamics and pair structure of dense liquids composed of interpenetrating ring polymers and a simple globule model.
• To investigate the influence of macromolecular architecture and volume fraction on system properties.

Main Methods:

• Employing field theoretic polymer integral equation theory.
• Constructing a theoretical framework for a globule model with fractal mass distribution (dF = ds = 3).
• Utilizing a two-fractal exponent ring model for the intramolecular structure factor, incorporating chain-like and space-filling regimes.

Main Results:

• Predicted exponential variation of dimensionless compressibility and pressure with macromolecular volume fraction in an isochoric ensemble.
• Identified an intermolecular correlation hole extending to small length scales for the globule model.
• Observed effective volume fraction growth and crossover to logarithmic growth with increasing degree of polymerization (N) in ring liquids, with a weaker correlation hole.

Conclusions:

• The developed theory provides a useful model for soft nanoparticle suspensions and serves as a reference for ring liquids.
• The findings on ring polymer liquids, including saturation of nearest neighbor rings at large N, align with simulation data.
• The theoretical tools are applicable to other partially interpenetrating soft objects like nanogels and microgels.