Abstract: A process for preparing solid polymer blends and composites of controlled porosity in microemulsions containing both hydrophilic and hydrophobic phases. The microemulsions are prepared with surfactant systems that may include a cosolvent as a part thereof, together with a hydrophilic monomer, or monomers, dissolved in the hydrophilic phase of the microemulsion, and a hydrophobic monomer, or monomers, dissolved in the hydrophobic phase. Polymerization of the monomers thus present is carried out to provide highly uniform dispersions of the resulting polymers in each other. The invention allows for the control of the morphology of the blends, the improvement in compatability of otherwise incompatible polymers, and improvements in the processability of the polymers due to enhanced thermal and mechanical properties.