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Penczek S, Pretula J. Activated Monomer Mechanism (AMM) in Cationic Ring-Opening Polymerization. The Origin of the AMM and Further Development in Polymerization of Cyclic Esters. ACS Macro Lett 2021; 10:1377-1397. [PMID: 35549023 DOI: 10.1021/acsmacrolett.1c00509] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The origin of the activated monomer mechanism (AMM) in cationic ring-opening polymerization (CROP) is described first. Then, conditions leading to the active chain end (ACE) mechanism and AMM are compared, as well as methods allowing to distinguish between these two mechanisms. These methods are based on the "ion trapping" of the active ionic species using highly basic phosphines or by comparing ACE and AMM kinetics of polymerization. The major factors deciding on the actual mechanism include: basicity of the monomers, ring strain, and the presence of the protic additives in the reaction system. These factors are tabulated for major cyclic ethers and cyclic esters. The historically evolved subsequent steps of AMM in the polymerization of cyclic esters are described: from the first experiments with trialkyloxonium salts, precursors of protonic acids, and added alcohols, via HCl as catalyst, and then CF3S(═O)2OH (polymerizing lactides) to the most popular derivatives of phosphoric acid, like diphenyl phosphate. Conditions allowing to synthesize poly(ε-caprolactone) (PCL), according to AMM-CROP, with molar mass up to 105 g·mol-1, are described as well as methods to polymerize CL with a protic initiator and acidic catalyst in one molecule. Then various methods enhancing the activity of the polymerizing systems are compared, based predominantly on hydrogen bonding, either to the polymer active end group (usually the hydroxyl group) or to the acid anion. Finally, kinetic equations for ACE and AMM are compared, and it is shown that the majority of the AMM-CROP systems, mostly studied for CL and lactides, proceed as living/controlled polymerizations. Since polymer end groups are hydroxyl groups, then, as it was shown in several papers, any initiator with one or many hydroxyl groups provides macromolecules with the corresponding architecture. The papers on synthetic methods are not discussed in detail.
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Affiliation(s)
- Stanislaw Penczek
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland
| | - Julia Pretula
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland
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Christodoulou E, Klonos PA, Tsachouridis K, Zamboulis A, Kyritsis A, Bikiaris DN. Synthesis, crystallization, and molecular mobility in poly(ε-caprolactone) copolyesters of different architectures for biomedical applications studied by calorimetry and dielectric spectroscopy. SOFT MATTER 2020; 16:8187-8201. [PMID: 32789409 DOI: 10.1039/d0sm01195a] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In this work, we synthesized poly(ε-caprolactone) (PCL) and three copolyesters of different architectures based on three different alcohols, namely a three arm-copolymer based on 1% glycerol (PCL_Gly), a four arm-copolymer based on 1% pentaerythrytol (PCL_PE), and a linear block copolymer based on ∼50% methoxy-poly(ethylene glycol) (PCL_mPEG), all simultaneously with the ring opening polymerization (ROP) of PCL. Due to their biocompatibility and low toxicity, these systems are envisaged for use in drug delivery and tissue engineering applications. Due to the in situ ROP during the copolyesters synthesis, the molecular weight of PCL, Wm initially ∼62 kg mol-1, drops in the copolymers from ∼60k down to ∼5k. For the structure-properties investigation we employed differential scanning calorimetry (DSC and TMDSC), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), Fourier transform infra red (FTIR) spectroscopy, polarized optical microscopy (POM), broadband dielectric spectroscopy (BDS) and isothermal water sorption. DSC revealed that the crystalline fraction of PCL increases whereas the crystallization rate drops in the copolymers in the order PCL ∼ PCL_Gly > PCL_PE ≫ PCL_mPEG, which coincides with that of decreasing Wm. In PCL_mPEG the major amount of PCL (87%) was found to crystallize while the majority of mPEG (92%) was found amorphous exhibiting constrained amorphous mobility and severely slower/weaker crystallization as compared to neat mPEG. Segmental dynamics in BDS, in agreement with DSC, is similar and in general slow for the samples of star-like structure for Wm ≥ 30k arising from PCL, whereas it is severely faster and enhanced in strength for the linear PCL_mPEG (lower Wm) copolymer arising from mPEG. For the latter system, the data provide indications for the formation of complex structures consisting of many small PCL crystallites surrounded by amorphous mPEG segments with constrained dynamics and severely suppressed hydrophilicity. These effects cannot be easily assessed by conventional XRD and POM, confirming the power of the dielectric technique. The overall recordings indicated that the different polymer architecture results in severe changes in the semicrystalline morphology, which demonstrates the potential for tuning the final product performance (permeability, mechanical).
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Affiliation(s)
- Evi Christodoulou
- Department of Chemistry, Laboratory of Polymer Chemistry and Technology, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Greece.
| | - Panagiotis A Klonos
- Department of Chemistry, Laboratory of Polymer Chemistry and Technology, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Greece. and Department of Physics, National Technical University of Athens (NTUA), Zografou Campus, 15780, Athens, Greece
| | - Kostas Tsachouridis
- Department of Chemistry, Laboratory of Polymer Chemistry and Technology, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Greece.
| | - Alexandra Zamboulis
- Department of Chemistry, Laboratory of Polymer Chemistry and Technology, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Greece.
| | - Apostolos Kyritsis
- Department of Physics, National Technical University of Athens (NTUA), Zografou Campus, 15780, Athens, Greece
| | - Dimitrios N Bikiaris
- Department of Chemistry, Laboratory of Polymer Chemistry and Technology, Aristotle University of Thessaloniki, GR-541 24, Thessaloniki, Greece.
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Zamboulis A, Nakiou EA, Christodoulou E, Bikiaris DN, Kontonasaki E, Liverani L, Boccaccini AR. Polyglycerol Hyperbranched Polyesters: Synthesis, Properties and Pharmaceutical and Biomedical Applications. Int J Mol Sci 2019; 20:E6210. [PMID: 31835372 PMCID: PMC6940955 DOI: 10.3390/ijms20246210] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 12/02/2019] [Accepted: 12/04/2019] [Indexed: 12/13/2022] Open
Abstract
In a century when environmental pollution is a major issue, polymers issued from bio-based monomers have gained important interest, as they are expected to be environment-friendly, and biocompatible, with non-toxic degradation products. In parallel, hyperbranched polymers have emerged as an easily accessible alternative to dendrimers with numerous potential applications. Glycerol (Gly) is a natural, low-cost, trifunctional monomer, with a production expected to grow significantly, and thus an excellent candidate for the synthesis of hyperbranched polyesters for pharmaceutical and biomedical applications. In the present article, we review the synthesis, properties, and applications of glycerol polyesters of aliphatic dicarboxylic acids (from succinic to sebacic acids) as well as the copolymers of glycerol or hyperbranched polyglycerol with poly(lactic acid) and poly(ε-caprolactone). Emphasis was given to summarize the synthetic procedures (monomer molar ratio, used catalysts, temperatures, etc.,) and their effect on the molecular weight, solubility, and thermal and mechanical properties of the prepared hyperbranched polymers. Their applications in pharmaceutical technology as drug carries and in biomedical applications focusing on regenerative medicine are highlighted.
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Affiliation(s)
- Alexandra Zamboulis
- Laboratory of Polymer Chemistry & Technology, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (A.Z.); (E.A.N.); (E.C.)
| | - Eirini A. Nakiou
- Laboratory of Polymer Chemistry & Technology, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (A.Z.); (E.A.N.); (E.C.)
| | - Evi Christodoulou
- Laboratory of Polymer Chemistry & Technology, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (A.Z.); (E.A.N.); (E.C.)
| | - Dimitrios N. Bikiaris
- Laboratory of Polymer Chemistry & Technology, Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece; (A.Z.); (E.A.N.); (E.C.)
| | - Eleana Kontonasaki
- Department of Dentistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece;
| | - Liliana Liverani
- Institute of Biomaterials, Department of Material Science and Engineering, University of Erlangen-Nuremberg, Cauerstr. 6, 91058 Erlangen, Germany;
| | - Aldo R. Boccaccini
- Institute of Biomaterials, Department of Material Science and Engineering, University of Erlangen-Nuremberg, Cauerstr. 6, 91058 Erlangen, Germany;
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Malinová L, Brožek J. Ethyl magnesium bromide as an efficient anionic initiator for controlled polymerization of ε-caprolactone. Polym Bull (Berl) 2013. [DOI: 10.1007/s00289-013-1048-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Jiang G, Jones IA, Rudd CD, Walker GS. Mechanistic study of Sn(Oct)2-catalyzed ε-caprolactone polymerization using Sn(Oct)2/BF3dual catalyst. J Appl Polym Sci 2009. [DOI: 10.1002/app.30597] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Baśko M, Kubisa P. Polyester oligodiols by cationic AM copolymerization ofL,L-lactide and ɛ-caprolactone initiated by diols. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pola.22065] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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