Polymer matrix composite comprising a porous polymeric network; and a plurality of thermally insulating particles distributed within the polymeric network structure, wherein the thermally insulating particles are present in a range from 15 to 99 weight percent, based on the total weight of the thermally insulating particles and the polymer (excluding the solvent); and wherein the polymer matrix composite has a density not greater than 3 g/cm3; and methods for making the same. The polymer matrix composites are useful, for example, in electronic devices.