Polymers of Carbonic Acid. 16. High Molecular Weight Poly(Neopentanediol Carbonate) by Ring-Opening Polymerization withnBuSnCl3or SnOct2as Initiators

Abstract

Abstract Neopentanediol carbonate, NPC, was polymerized in bulk at 120°C. Either nBuSnCl3 or Sn(II)2-ethylhexanoate (SnOct2) were used as initiators. The reaction time and the monomer/initiator (M/I) ratio were varied. Polymerizations initiated with nBuSnCl3 were more rapid and yielded higher molecular weights (M n up to 150,000 and M w up to 270,000). Furthermore, the molecular weights were almost independent of the M/I ratio, provided the reaction time was optimized. In contrast, the molecular weights of the SnOct2-initiated polymers paralled the M/I ratios more or less. This finding and the 1H-NMR spectra suggest that stoichiometric reactions between monomer and SnOct2 take place, yielding polymers with covalently bound octoate and OH endgroups. Finally, the polymerizability of NPC recrystallized from CCl4 or from tetrahydrofuran was compared. No significant difference was found when nBuSnCl3 was used as initiator, whereas in the case of SnOct2 a difference was observed. NPC recrystallized from CCl4 polymerized more rapidly and gave higher molecular weights than NPC recrystallized from THF.