Kinetics of Polymer Gel Formation Cause Deviation from Percolation Theory in the Dilute Regime

• DOI: 10.1021/acs.macromol.3c00831
• Publication Date: 2023-11-14T12:18:25Z
• Authors: Haley K. Beech; Tzyy-Shyang Lin; Devosmita Sen; Dechen Rota; Bradley D. Olsen
• Keywords: Gel point; Percolation (cognitive psychology); Critical point (mathematics); Percolation Theory

Gelation has long been conceptualized and modeled as a percolation process in which bond formation or destruction events are random. Percolation assumes that connections created destroyed randomly such the critical point should occur at same when approached from either direction. Here, gel of an end-linked poly(ethylene glycol) was measured during forward (bond forming) reverse breaking) gelation degelation processes to interrogate how scales with synthesis concentration, where decreased concentration leads increased prevalence inelastic loops. Forward points, combined kinetic nuclear magnetic resonance (NMR) diffusing wave spectroscopy (DWS) experiments, were identical results generated Monte Carlo (KMC) simulation, demonstrating expected suppression decreased. Reverse selective degradation technique, within error points high concentrations but displayed lesser degree This deviation between low qualitatively reproduced KMC simulation. These experiments simulations show diverge system becomes more dilute, suggesting effects cause departure behavior defect-rich gels.