We apply the kinetic multi-layer model of gas-particle interactions (KM-GAP) to simulate the reactive uptake of ozone into a 150 nm diameter BBOA particle for three different cases: 1) a particle comprising only the hydrophobic phase; 2) a particle comprising only the hydrophilic phase, similar to studies that investigate only the water-soluble component of BBOA samples; and 3) a particle that has undergone LLPS to consist of an inner hydrophilic core and an outer hydrophobic shell. The KM-GAP model is described in more detail in the Material and Methods section, and elsewhere . The model explicitly treats mass transport including gas-phase O3 diffusion, adsorption and surfaceto-bulk transport of O3, and bulk diffusion of BrC and O3 within the core and shell phase as well as multiphase reactions between O3 and BrC.