Chain Folding Produces a Multilayered Morphology in a Precise Polymer: Simulations and Experiments

Area of Science:

• Polymer Science
• Materials Science
• Nanotechnology

Background:

• Precise control over polymer architecture is key for designing self-assembled nanostructures.
• Functional polyethylenes offer potential for tailored material properties.

Purpose of the Study:

• To elucidate the crystal structure of a semicrystalline polyethylene with precisely placed pendant carboxylic acid groups.
• To understand the chain folding mechanism and resulting nanometer-scale features.

Main Methods:

• Atomistic molecular dynamics simulations.
• Experimental X-ray scattering.
• Raman spectroscopy.

Main Results:

• The polymer chains exhibit hairpin folding near each carboxylic acid group.
• This folding creates multiple embedded layers of functional groups with an interlayer distance of 2.5 nm.
• This folding pattern contrasts with the mostly trans-chain conformation in other precise polyethylenes.

Conclusions:

• The unique hairpin folding in this functional polyethylene leads to embedded functional layers.
• These layers present potential as two-dimensional pathways for ionic or molecular transport.