Chain Conformation of Polymers Densely Grafted onto Plate-Shaped Particles

Polymer-grafted platelets (PGPLs) were prepared via atom transfer radical polymerization of butyl methacrylate with the initiator bonded to the surface of hematite platelets, and the conformation of the poly(butyl methacrylate) (PBMA) chains grafted onto the top and bottom of the platelets at a dimensionless graft density (σ*) of 0.3–0.9 was studied. PGPLs were shaped into films with platelets parallel to the film surface via dispersion casting followed by hot pressing. The face-to-face distance between platelets increases with the number-average molecular weight of the grafted polymer and equals 2Lcσ*, where Lc is the contour length of the grafted PBMA chains. This suggests that the polymer chains grafted onto a platelet are stretched perpendicular to the platelet face to a similar extent as those grafted onto flat substrates, and their ends are opposed to those grafted from the opposite platelets to fill the space between the platelets.