Cobalt-Containing Hyperbranched Poly(silylenearylene)s

A group of hyperbranched poly(silylenearylene)s are synthesized by homopolycyclotrimerizations of A(2)-type silylenediynes. The polymers can be readily metallized by complexations of their periphery triple bonds with cobalt octacarbonyls Co-2(CO)(8). Pyrolysis of these organometallic polymers gives magnetic ceramics in good yields. Analyses by SEM, TEM, XPS, EDX, and XRD demonstrate that the ceramics comprise ferromagnetic Co and paramagnetic Co2Si nanocrystallites wrapped by carboneous shell. The ceramics show high magnetic susceptibilities (M (s) up to similar to 50 emu/g) and near-zero coercivity (H (c) down to similar to 0.14 kOe), suggesting that they are good soft magnetic materials with low hysteresis loss.