Poly(10-undecene-1-ol) characterized by MALDI-TOF MS and NMR spectroscopy

Abstract

Poly(10-undecene-1-ol)s were synthesized by metallocene-catalyzed polymerization. MALDI-TOF MS allows obtaining detailed information on the monomer units in the polymer chains and the nature of the head and end groups of these polymers in dependence on the Al alkyl triisobutyl aluminum (TIBA) as well as methylalumoxan (MAO), both used as protecting agent for the hydroxyl groups of the monomer. The peak-to-peak distances of the main peaks could be distinctly assigned to the monomer unit 10-undecene-1-ol. Evaluating the MALDI-TOF peak distributions, polymers with -H, -C4H9, -CH3 head groups in combination with vinylidene and saturated (–CH3) end groups could be detected. By 1H NMR spectroscopy, it was verified that with the used catalysts polymers with vinylidene end groups were obtained predominantly. The presence of saturated end groups could be proved qualitatively by combination of 1H and 13C NMR spectroscopy for polymers produced by TIBA protection, which strikingly confirm the results from MALDI-TOF MS. For the polymers prepared with only MAO protection, saturated groups are also proved but discrimination between head and end groups was not possible. A polymerization mechanism corresponding to the detected different head and end groups is proposed.