Perspective: Single polymer mechanics across the force regimes [corrected].

Area of Science:

• Polymer Physics
• Materials Science
• Biophysics

Background:

• The mechanical response of single polymers is a long-standing theoretical challenge, initially motivated by rubber's thermomechanical properties.
• Historically, polymer elasticity calculations primarily explained bulk material behavior.
• The advent of high-precision single-chain stretching experiments (force spectroscopy) in the 1990s enabled direct testing of theoretical models.

Purpose of the Study:

• To review theoretical and experimental results on the force-extension response of single polymers.
• To focus on scaling laws in low-force elastic regimes and recent experimental measurements.
• To assess the validity of major elasticity models against experimental data and explore insights into polymer structure.

Main Methods:

• Review of theoretical models including blob-chain, linear response theory, freely jointed chain, and worm-like chain models.
• Analysis of experimental data from high-precision single-chain stretching experiments (force spectroscopy).
• Comparison of model predictions with experimental results across different force regimes.

Main Results:

• Discussion of five major single-chain elasticity models and their applicable force regimes.
• Assessment of the rigorous validation of each model against experimental findings.
• Demonstration of how experimental data can reveal new information about polymer structure, particularly for polyelectrolytes.

Conclusions:

• Experimental force spectroscopy provides crucial validation for theoretical polymer elasticity models.
• Understanding polymer elasticity at the single-chain level offers insights into bulk material properties.
• Single-chain polymer mechanics experiments can uncover fundamental aspects of polymer structure and behavior, especially in charged polymers.