Gas phase mineralized graphene as core/shell nanosheet supports for single-site olefin polymerization catalysts and in-situ formation of graphene/polyolefin nanocomposites

A versatile gas phase mineralization process affords nanosheets containing a functionalized graphene (FG) core and a thin silica shell. The number of cycles, exposing FG to sequenced tetrachlorosilane and water vapors, controls the silica content and the silica shell thickness. The resulting high surface area core/shell nanosheets, containing 22 to 34 wt.-% silica, are used to immobilize single-site catalysts. During polymerization, the FG/silica nanosheets are uniformly dispersed in ultrahigh molecular weight polyethylene. This catalytic polymerization filling process, exploiting the encapsulation of graphene in a silica shell, is of interest to prepare electrically insulating carbon/polyolefin composite materials with high thermal conductivity useful in lightweight engineering.