Determination of stereochemical compositions of oligo- and poly(alpha-methylstyrene)s by H-1 and C-13 NMR

A set of oligo- and poly(alpha-methylstyrene) samples were prepared by anio nic polymerization, giving particular attention to the polymerization tempe rature and the initial monomer concentration. The samples were characterize d by H-1 and C-13 NMR spectroscopy and also by three kinds of two-dimension al NMR spectroscopy. It is shown that they have almost the same value 0.72 +/- 0.01 of the fraction f(r) of raceme diads independent of molecular weig ht, indicating that they are adequate for a study of dilute polymer solutio ns within the new framework of polymer solution science based on the helica l wormlike chain model.