Polystyrene Chain Geometry Probed by Ion Mobility Mass Spectrometry and Molecular Dynamics Simulations

Area of Science:

• Polymer Chemistry
• Computational Chemistry
• Analytical Chemistry

Background:

• Polystyrene (PS) is a widely used thermoplastic polymer with valuable bulk properties.
• Designing functional PS with defined structures is crucial but limited by analytical methods for atomistic folding.
• Understanding gas-phase ion structures is key to advancing PS functionalization.

Purpose of the Study:

• To investigate the gas-phase structure of polystyrene ions with varying end groups.
• To determine how monomer rigidity and end-group nature influence charge stabilization in PS ions.
• To compare the structural behavior of PS ions with other polymer types, like polyethers.

Main Methods:

• Ion mobility spectrometry coupled with molecular dynamics (MD) simulations.
• Analysis of gas-phase polystyrene ions with different end groups.
• Comparison of simulation data with experimental observations.

Main Results:

• Polystyrene ions exhibit charges located at the periphery of the polymer backbone, not deep within the structure.
• Singly and doubly charged PS ions adopt dense, elliptic-shaped structures.
• MD simulations show phenyl ring interactions drive PS chain folding, excluding charge from the core, unlike flexible polyether ions.

Conclusions:

• The rigid, apolar nature of polystyrene dictates unique gas-phase ion structures with peripheral charge localization.
• This finding provides critical insights for designing functional polystyrenes with controlled folding and charge distribution.
• The study highlights the power of integrating ion mobility and MD simulations for characterizing polymer ion structures.