A Novel Approach to Biodegradable Block Copolymers of ε‐Caprolactone and δ‐Valerolactone Catalyzed by New Aluminum Metal Complexes
- 7 December 2004
- journal article
- research article
- Published by Wiley in Macromolecular Bioscience
- Vol. 4 (12), 1092-1104
- https://doi.org/10.1002/mabi.200400128
Abstract
Summary: The chemical preparation of structurally well-defined biodegradable amphiphilic block copolymers is now of great interest for biomedical applications and the fundamental mimetic study of biomacromolecule self-assembly. For this purpose, in this study, (R,R)-N,N′-bis(3-tert-butylsalicylidene)-1,2-cyclohexanediamine 2 as a ligand was first synthesized from 1,2-cyclohexanediamine (DACH) and was allowed to further react with AlMe3, leading to a precursor compound 3. Then, the novel five-coordinated aluminum metal complexes 4–6 and 7–8 were prepared with good yields of 80–90%, bearing various molar mass monofunctional methoxy-poly(ethylene glycol) MPEG and difunctional poly(ethylene glycol) PEG as the alkoxy moieties, respectively. By means of nuclear magnetic resonance spectrometry (NMR), mass spectrometry (MALDI-FTMS) and Fourier Transform infrared spectrometry (FT-IR), new metal aluminum complexes 4–8 were characterized as having distinct chemical structures. Utilizing the synthesized metal complexes 4–8 as novel coordination polymerization catalytic templates, biodegradable amphiphilic MPEG-b-PCL, MPEG-b-PVL, PCL-b-PEG-b-PCL and PVL-b-PEG-b-PVL were synthesized with good control of the molecular weight distribution via the ring opening polymerization of ε-caprolactone and δ-valerolactone monomers at 100 °C in toluene. In addition, the chemical and crystalline structures and the thermal properties of these block biodegradable copolymers were analyzed by means of NMR, gel permeation chromatography (GPC), wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). It was found that the melting points and crystallinities of the block copolymers synthesized strongly depended on the molecular structures of the polyether and polyester building blocks. Only one glass transition stage was detected, indicating good chain/segmental miscibility between the hydrophilic MPEG/PEG and hydrophobic PCL/PVL blocks in the non-crystalline regions. Moreover, TGA analysis exhibited typical two-step decomposition profiles with the weight-loss percentages in good agreement with block compositions from NMR calculations.Keywords
This publication has 32 references indexed in Scilit:
- Polycaprolactone−Poly(ethylene glycol) Multiblock Copolymers as Potential Substitutes for Di(ethylhexyl) Phthalate in Flexible Poly(vinyl chloride) FormulationsBiomacromolecules, 2003
- Living Ring-Opening (Co)polymerization of 6,7-Dihydro-2(5H)-oxepinone into Unsaturated Aliphatic PolyestersMacromolecules, 2001
- Synthesis and characterization of poly(oxyethylene)-poly(caprolactone) multiblock copolymersPolymer International, 1998
- Synthesis of Amine-Terminated Aliphatic Polycarbonates via Al(Et)2(OR)-Initiated PolymerizationsMacromolecules, 1997
- Macromolecular Engineering of Lactones and Lactides. 24. Controlled Synthesis of (R,S)-β-Butyrolactone-b-ε-Caprolactone Block Copolymers by Anionic and Coordination PolymerizationMacromolecules, 1997
- Polylactones 27. Anionic polymerization of L-lactide. Variation of endgroups and synthesis of block copolymers with poly(ethylene oxide)Makromolekulare Chemie. Macromolecular Symposia, 1993
- Polymers for biodegradable medical devices: VIII. Hydroxybutyrate-hydroxyvalerate copolymers: physical and degradative properties of blends with polycaprolactoneBiomaterials, 1992
- Block Copolymer Thermodynamics: Theory and ExperimentAnnual Review of Physical Chemistry, 1990
- Polyether-polyester block copolymers by non-catalysed polymerization of ɛ-caprolactone with poly(ethylene glycol)Polymer, 1989
- Aliphatic polyesters. I. The degradation of poly(ϵ‐caprolactone) in vivoJournal of Applied Polymer Science, 1981