(Co)polymer matrix composites including a porous (co)polymeric network; a multiplicity of thermally-conductive particles and a multiplicity of magnetic particles distributed within the (co)polymeric network structure; wherein the thermally-conductive particles, magnetic particles and optional magnetic particles are present in a range from 15 to 99 weight percent, based on the total weight of the particles and the (co)polymer (excluding the solvent). Methods of making and using the (co)polymer matrix composites are also disclosed. The (co)polymer matrix composites are useful, for example, as heat dissipating or heat absorbing thermal interface materials that also provide magnetic properties useful, for example, in flux field directional materials or shielding from electromagnetic interference.