Recent Developments in Ring Opening Polymerization of Lactones for Biomedical Applications

Albertsson, † and Ann-Christine; Varma, I. K.

doi:10.1021/bm034247a

Cited by 1,479 publications

(1,350 citation statements)

References 356 publications

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“…Zhang et al 68,69 reported similar observations with aluminum complexes of functionalized phenolate ligands, which he interpreted to arise from higher reaction temperatures resulting in transesterification. [70][71][72] However, it could also be that when 4 and 5 are used, initiation proceeds via acid-initiation (HCl generated in situ from adventitious water) and this reaction is more uncontrolled than in reactions catalyzed by an Al-alkyl/alcohol system. Another possibility is that the reaction may be proceeding via a reaction pathway involving insertion of the monomer into the Al-Cl bond.…”

Section: Ring-opening Polymerization Of ε-Caprolactonementioning

confidence: 99%

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

et al. 2012

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Abstract:A series of aluminum methyl and chloride complexes bearing 2(N-piperazinyl-N′-methyl)-2-methylene-4-R′-6-R-phenolate or 2(N-morpholinyl)-2-methylene-4-R′-6-R-phenolate ([ONE R1,R2 ]-) {[ R 1 = t Bu, R 2 = Me, E = NMe (L1); R 1 = R 2 = t Bu, E = NMe (L2); R 1 = R 2 = t Bu, 1 E = O (L3)} ligands were synthesized and characterized through elemental analysis, 1 H, 13 The catalytic activity of complexes 1-3 toward ring-opening polymerization (ROP) of ε-caprolactone was assessed. These complexes are more active than analogous Zn complexes for this reaction but less active than the Zn analogs for ROP of rac-lactide. Characteristics of the polymer as well as polymerization kinetics and mechanism were studied. Polymer end-group analyses were achieved using 1 H NMR spectroscopy and MALDI-TOF MS. Eyring analyses were performed and the activation energies for the reactions were determined, which were significantly lower for 1 and 2 compared with 3. This could be for several reasons: (1) the methylamine (NMe) group of 1 and 2, which is a stronger base than the ether (O) group of 3, might activate the incoming monomer via non-covalent interactions, and/or (2) the ether group is able to temporarily coordinate to the metal center and blocks the vacant coordination site towards incoming monomer, whilst the amine cannot do this. Preliminary studies using 4 and 5 towards copolymerization of cyclohexene oxide with carbon dioxide have been performed. 4 was inactive and 5 afforded polyethercarbonate (66.7% epoxide conversion, polymer contains 54.0% carbonate linkages).

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Section: Ring-opening Polymerization Of ε-Caprolactonementioning

confidence: 99%

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

et al. 2012

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“…The synthesis of novel polymer structures through ring opening polymerization (ROP) has been studied for several years [27][28][29] and is the most popular route for poly(α-ester) synthesis. One of the most important factors that influences the properties of aliphatic polyesters is the molecular weight, with high molecular weight materials generally having better mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of a novel terpolymer based on L-lactide, D,L-lactide and trimethylene carbonate

Motta

Duek

2014

Mat. Res.

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Terpolymers of L-lactide, D,L-lactide and trimethylene carbonate (TMC) were synthesized via the ring-opening polymerization reaction for cyclic monomers using stannous octoate as the initiator at a ratio of ~0.05 mol% (monomers/(SnOct) 2 ). Synthesis was done at 130 °C for 48 h. The inclusion of TMC, an aliphatic elastomeric polycarbonate, alongside polymer chain segments containing L-lactide and D,L-lactide, was expected to yield a material with improved properties such as increased elongation; this would overcome the limitation of copolymers consisting entirely of lactide and D,L-lactide. The terpolymer properties were assessed by Nuclear magnetic resonance spectroscopy 1 H and 13 C NMR, infrared spectroscopy, differential scanning calorimetry and thermogravimetry, with particular attention being given to the effect of TMC on the copolymer of L-lactide-co-D,L-lactide. The mixing of these polymers resulted in material with a high molar mass (10 5 g/mol). The mechanical properties of the terpolymer were assessed using pins of this material that were tested by mechanical flexion at three points. When compared with results for the copolymer PLDLA there was a decrease in Young's modulus for the TMC-containing terpolymer.

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“…These polymers and various copolymer compositions have shown considerable potential as effective drug carriers [41,42] and have been extensively studied for the controlled release of drugs due to their tunable degradation rates (from months to years), wide range of mechanical properties and biodegradability [40,[43][44][45][46][47][48][49]. Poly(l-lactide) (PLLA) is particularly advantageous since its degradation product, lactic acid, is well tolerated by the body [50][51][52][53]. The degradation properties of polyesters have been widely studied [54,55] and are known to be affected by polymer properties (i.e., molecular weight, chemistry, wettability and crystallinity) and also the properties of the release medium (i.e., pH, ionic strength and solvent) [56].…”

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confidence: 99%

Controlled Drug Delivery From Composites of Nanostructured Porous Silicon and Poly( L -Lactide)

et al. 2012

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Aims: Porous silicon (pSi) and poly(L-lactide) (PLLA) both display good biocompatibility and tunable degradation behavior, suggesting that composites of both materials are suitable candidates as biomaterials for localized drug delivery into the human body. The combination of a pliable and soft polymeric material with a hard inorganic porous material of high drug loading capacity may engender improved control over degradation and drug release profiles and be beneficial for the preparation of advanced drug delivery devices and biodegradable implants or scaffolds. Materials & methods: In this work, three different pSi and PLLA composite formats were prepared. The first format involved grafting PLLA from pSi films via surface-initiated ring-opening polymerization (pSi–PLLA [grafted]). The second format involved spin coating a PLLA solution onto oxidized pSi films (pSi–PLLA [spin-coated]) and the third format consisted of a melt-cast PLLA monolith containing dispersed pSi microparticles (pSi–PLLA [monoliths]). The surface characterization of these composites was performed via infrared spectroscopy, scanning electron microscopy, atomic force microscopy and water contact angle measurements. The composite materials were loaded with a model cytotoxic drug, camptothecin (CPT). Drug release from the composites was monitored via fluorimetry and the release profiles of CPT showed distinct characteristics for each of the composites studied. Results: In some cases, controlled CPT release was observed for more than 5 days. The PLLA spin coat on pSi and the PLLA monolith containing pSi microparticles both released a CPT payload in accordance with the Higuchi and Ritger–Peppas release models. Composite materials were also brought into contact with human lens epithelial cells to determine the extent of cytotoxicity. Conclusion: We observed that all the CPT containing materials were highly efficient at releasing bioactive CPT, based on the cytotoxicity data. Original submitted 16 December 2010; Revised submitted 29 September 2011; Published online 6 March 2012

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Recent Developments in Ring Opening Polymerization of Lactones for Biomedical Applications

Cited by 1,479 publications

References 356 publications

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

Aluminum Methyl and Chloro Complexes Bearing Monoanionic Aminephenolate Ligands: Synthesis, Characterization, and Use in Polymerizations

Synthesis and characterization of a novel terpolymer based on L-lactide, D,L-lactide and trimethylene carbonate

Controlled Drug Delivery From Composites of Nanostructured Porous Silicon and Poly( L -Lactide)

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