Polymer-derived elastic heat spreader films

An elastic heat spreader film comprising:

• A) A graphitic film prepared from graphitization of a polymer film or pitch film, wherein said graphitic film has graphitic crystals substantially parallel to one another and parallel to a film plane, having an inter-graphene spacing less than 0.34 nm in said graphitic crystals, and wherein said graphitic film has a thermal conductivity of at least 600 W/mK, an electrical conductivity no less than 4,000 S/cm, and a physical density greater than 1.5 g/cm3, all measured without the presence of a resin;
• and
• B) an elastomer or rubber that permeates into said graphitic film from at least a surface of said graphitic film;
• wherein said elastomer or rubber is in an amount from 0.001% to 30% by weight based on the total heat spreader film weight;
• wherein said elastic heat spreader film has a fully recoverable tensile elastic strain from 2% to 100% and an in-plane thermal conductivity from 100 W/mK to 1,750 W/mK.