Surface-Initiated Polymerization with an Initiator Gradient: A Monte Carlo Simulation

Area of Science:

• Polymer Science
• Materials Science
• Computational Chemistry

Background:

• Gradient brushes (GBs) properties like molecular weight (Mn) and grafting density (σ) are difficult to characterize.
• Traditional analysis assumes uniform spatial properties for simplification.

Purpose of the Study:

• To investigate the assumption of uniform properties in gradient brushes (GBs).
• To explore surface-initiated polymerizations (SIPs) with initiator gradients using simulations.

Main Methods:

• Utilized a stochastic reaction model (SRM) for heterogeneous polymerizations.
• Employed lattice Monte Carlo simulations to model SIPs with initiator gradients.

Main Results:

• Increased grafting density (σ) slows polymerization, reducing molecular weight (Mn) and increasing dispersity (Đ).
• SIPs with initiator gradients show position-dependent polymer properties (lower Mn, higher Đ in high σ regions).
• Observed significant deviation in brush height scaling with σ compared to existing data.

Conclusions:

• Gradient brushes (GBs) exhibit inherent non-uniformity in polymer properties.
• Non-uniform molecular weight (Mn) and dispersity (Đ) explain deviations in brush height scaling behavior.