Systematic derivation of implicit solvent models for the study of polymer collapse

Area of Science:

• Polymer Physics
• Computational Chemistry
• Soft Matter Physics

Background:

• Polymer chain conformations in water depend on complex interactions.
• Explicit solvent models are computationally expensive.
• Implicit solvent models offer a computationally feasible alternative.

Purpose of the Study:

• To systematically derive implicit water models.
• To evaluate the impact of solvent representation simplification on polymer conformations.
• To compare explicit water, implicit solvent, and vacuum simulations.

Main Methods:

• Developed implicit solvent models from an explicit coarse-grained water model.
• Generated potentials of mean force using umbrella sampling and replica exchange molecular dynamics.
• Simulated hydrophobic homopolymers of varying lengths.

Main Results:

• Implicit solvent models showed limitations in capturing key interaction energetics.
• Vacuum simulations unexpectedly provided more accurate polymer conformations than implicit models.
• An implicit model with a desolvation barrier led to spurious extended polymer structures.

Conclusions:

• Simplifying solvent representation requires careful model development.
• Vacuum simulations can be a surprisingly effective alternative for certain polymer studies.
• Current implicit solvent models may not accurately represent hydrophobic polymer behavior.