Preparation of polystyrene-graphite conducting nanocomposites via intercalation polymerization

In situ polymerization of styrene was conducted in the presence of expanded graphite obtained by rapid heating of a graphite intercalation compound (G IC), to form a polystyrene-expanded graphite conducting composite. The comp osite showed excellent electrically conducting properties even though the g raphite content was much lower than in normal composites. The transition of the composite from an electrical insulator to an electrical semiconductor occurred when the graphite content was 1.8wt%, which is much lower than tha t of conventional conducting polymer composites. TEM, SEM and other studies suggest that the graphite was dispersed in the form of nanosheets in a pol ymer matrix with a thickness of 10-30nm, without modification of the space between carbon layers and the structure of the graphite crystallites. The c omposite exhibited high electrical conductivity Of 10(-2)Scm(-1) when the g raphite content was 2.8-3.0wt%. This great improvement of conductivity coul d be attributed to the high aspect ratio (width-to-thickness) of the graphi te nanosheets. The rolling process strongly affected the conductivity and t he mechanical properties of the composite. (C) 2001 Society of Chemical Ind ustry.