Abstract: Inertial confinement fusion(ICF) experiments need the incorporation of dopant atoms into the low density foam. Through a phase-separation process, the Bromine (Br) doped foams with a typical density of 50 mg/cm3 were synthesized contaning 58.91% Br atom. A lamellar structure was observed in the scanning electron microscope (SEM) image of the PMP foam. The monomer hexabromobenzene acted as the “crystalloid” in the sol-gel process. As the dopant level increased, there were more “crystalloids”, which would make the lamellar become smaller. Taking the measurement error into account, the dopant was dispread uniformly in the foam sample. The thermo gravimetric analysis used in different dopant level indicates the solvent was removed completely from the whole foam system.