TITLE:
Highly Branched Poly(α-Methylene-γ-Butyrolactone) from Ring-Opening Homopolymerization
AUTHORS:
Pascal Binda, Zakiya Barnes, Dechristian Guthrie, Rasaan Ford
KEYWORDS:
Lanthanide, α-Methylene-γ-Butyrolactone, Polyesters, Ring-Opening Polymerization
JOURNAL NAME:
Open Journal of Polymer Chemistry,
Vol.7 No.4,
November
30,
2017
ABSTRACT: New heteroleptic lanthanide complex [L1ILaN{Si(CH3)2}] (1) containing tridentate
[ONO] ancillary ligand was synthesized from an acid-base ligand exchange
reaction with ligands H2L1 and corresponding homoleptic lanthanide
compound La[N{Si(CH3)3}2]3. Meanwhile, dimeric complexes [L1LaCl] (2)
and [L1ILaCl] (3) were prepared from salt metathesis reaction between one
equivalent of ligands H2LI,II, three equivalent of NaN{Si(CH3)3}2, and one equivalent
of LaCl3. These compounds were characterized by nuclear magnetic resonance
(300 MHz) and elemental analysis. These complexes were used as catalysts in
the ring-opening homopolymerization of α-methylene-γ-butyrolactone. While
compound 1 did not show any significant reactivity, compounds 2 and 3 gave
significant amount of highly branched poly(α-methylene-γ-butyrolactone) as
confirmed by 1H NMR spectroscopy and Malvern’s triple detector GPCMax
analysis in DMSO with molecular weights of over 500,000 Dalton. The
glass-transition temperatures of the branched polymer samples were determined
using a Dynamic Mechanical Analyzer, DMA Q800.