Simulating Light Scattering Behavior of Branched Molecules

Monte Carlo simulations reveal long chain branching (LCB) topology based on kinetics of systems like low-density polyethylene (ldPE). Examining the topologies computed shows the majority of branch arms to be short as compared to backbone length, while also a significant branch-on-branch fine structure is observed. Until now, predicting scattering function P^-1(θ) from LCB has only been successful for structures like simple combs or stars. Topologies in graph theoretical form are used to predict scattering function P^-1(θ) and ⟨R²_g⟩ by summating intramolecular distances, accounting for branching and excluded volume. Experimental size exclusion chromatography with multiangle light scattering can be brought in line with the predicted branching character. Branching is less than predicted due to a different fine structure in ldPE leading to stronger size contraction.