The effects of variable ionic liquid (IL) treatment time (1 s–60 min) on macroscale morphology evolution in biphasic cellulose xerogels were measured using nitrogen gas physisorption and Raman spectroscopy. Nitrogen gas adsorption/desorption measured a constant pore size (~ 12.5 nm diameter) in the xerogel phase and increasing BET surface area from 0.2 to 148.5 m²g⁻¹ with increasing IL treatment time. Cellulose decrystallization and epoxy penetration measured using Raman spectroscopy confirmed that the xerogel phase is continuous and composed of decrystallized regenerated cellulose. The porosity of the xerogel phase (ϕ_V,S) decreased from 0.89 to 0.57 while the full sample porosity (ϕ_V,T) increased from 0.34 to 0.50 with increasing IL treatment time. Three regimes were identified to describe the propagation and growth of the regenerated xerogel cellulose phase—Regime A, Regime B, and Regime C. These results are compared with non-porous samples formed using the same IL treatment conditions to elucidate the role of solvent exchange on cellulose regeneration in these heterogeneous materials.