A three-phase framework for photon scattering in porous nanocomposites

State-of-the-art theories generally treat these materials as two-phase systems consisting of particles and a matrix, overlooking the air pores that are intrinsically present in porous composites. Here we experimentally determine the scattering coefficients of six BaSO4-acrylic and TiO2-acrylic coatings spanning a range of particle volume fractions and develop a three-phase scattering framework that explicitly accounts for pore-induced scattering.

By representing the composite as two coupled scattering subsystems, particle-matrix and particle-air, the framework resolves discrepancies between theory and experiment: conventional two phase models substantially underpredict scattering in BaSO4 coatings while overpredicting scattering in TiO2 coatings, whereas the three-phase model accurately captures the observed trends and reduces the mean absolute logarithmic error from 0.667 to 0.379.