Certain embodiments relate to compositions that may be used as thermal interface materials in electronic assemblies. One such composition includes a block copolymer matrix comprising polystyrene and polybutene. The composition also includes a filler positioned in the copolymer matrix, the filler comprising carbon. The filler may in certain embodiments be a material selected from the group consisting of graphite, graphene, and carbon nanotubes. composition may include routing structures and their formation. Assemblies may include the composition positioned between a die and a heat spreader. Other embodiments are described and claimed.