Mass spectrometric assay of polymerization catalysts for combinational screening

Electrospray ionization mass spectrometry of a homogeneous Ziegler-Natta polymerization catalyzed by a Pd(II) diimine complex shows two distinct distributions of metal-bound oligomeric ions corresponding to catalytic centers which have not undergone chain transfer and those that have. A fit of two distributions by numerical integration of the kinetic equations describing the polymerization gives the absolute rates for initiation, propagation, and chain transfer in the polymerization reaction, from which the bulk polymer properties can be predicted. The mass spectrometric method requires mg quantities of catalyst, requires only a few minutes, and is suitable for both pooled and parallel screens of catalyst libraries. (C) 2000 Elsevier Science B.V.