Aliphatic Polycarbonates Research Articles

Segmented polyurethane elastomers derived from aliphatic polycarbonate and poly(ester‐carbonate) soft segments for biomedical applications

AbstractA series of biomedical polyurethane elastomers (PURs) based on poly(ester‐carbonate)s (PECs) and polycarbonates (PCs) were synthesized and spectrally characterized fully. PEC or PC diols were synthesized by the ring‐opening polymerization of ε‐caprolactone, trimethylene carbonate, and neopentyl carbonate catalyzed by lipase from Candida antarctica. PURs were prepared by free‐metal method from PEC or PC diols and 4,4′‐methylenebis(phenyl isocyanate), with 1,4‐butanediol as a chain extender. The physical and mechanical properties as well as hydrolytic stability of the obtained PURs were determined. The toxicity of the received polymers was evaluated using bacterial luminescence test and two protozoans assays. The presented preliminary studies suggest that PEC or PC diols prepared in this way might be applied for the synthesis of biomedical PURs with improved hydrolytic stability. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Synthesis of Poly(Urethane-Urea)s from Polycarbonate Macrodiols and IPDI with the Addition of Derivant of Propylene Carbonate

In this paper, poly(urethane-urea)s were synthesized from two aliphatic polycarbonate macrodiols with different molecular mass, isophoronodiisocyanate (IPDI) and a pseudo-chain extender, a derivant of propylene carbonate, which was synthesized by propylene carbonate and 1,6-diaminohexane. The obtained poly(urethane-urea) elastomers exhibit very good mechanical properties, they are colorless and transparent and could be applied in biomedical material field.

Effect of chemical structure of polycarbonates on entanglement spacing

The master curves of a series of aliphatic polycarbonates (APCs) with different lengths of methylene segments in the repeat unit were obtained by dynamic rheological measurements. The plateau modulus and entanglement molecular weight were determined and cross-checked by different methods. Though having distinct difference in chemical structure of repeat units, both APCs and bisphenol-A polycarbonates have the similar entanglement weight and entanglement spacing. On the other side, the plateau modulus decreases with increasing the length of the side group of aliphatic polycarbonates with different side-chain lengths in the literature. The packing length model can explain the relationship between chain structure and entanglements.

A Water‐Soluble Polycarbonate With Dimethylamino Pendant Groups Prepared by Enzyme‐Catalyzed Ring‐Opening Polymerization

A water-soluble polycarbonate with dimethylamino pendant groups, poly(2-dimethylaminotrimethylene carbonate) (PDMATC), is synthesized and characterized. First, the six-membered carbonate monomer, 2-dimethylaminotrimethylene carbonate (DMATC), is prepared via the cyclization reaction of 2-(dimethylamino)propane-1,3-diol with triphosgene in the presence of triethylamine. Although the attempted ring-opening polymerization (ROP) of DMATC with Sn(Oct)(2) as a catalyst fails, the ROP of DMATC is successfully carried out with Novozym-435 as a catalyst to give water-soluble aliphatic polycarbonate PDMATC with low cytotoxicity and good degradability.

The influence of hard segment content on mechanical and thermal properties of polycarbonate-based polyurethane materials

Aliphatic segmented polyurethanes were prepared by one-step procedure in catalytic reaction between polycarbonate diol, hexamethylene-diisocyanate and 1,4-butandiol (as chain extender). The hard segment content TS was varied (17, 24, 30 and 42 wt. %) by changing the ratio of starting compounds. The soft segment is made from flexible aliphatic polycarbonate diol, while hard segments consist of chain extender and diisocyanate component. In order to study the hydrogen bonding formation and phase separation, Fourier transform infrared spectroscopy (FT-IR) was used. Wide angle X-ray scattering (WAXS) was performed to determine a degree of crystallinity and to investigate the phase behavior of prepared elastomers. The effect of TS content on mechanical properties (tensile strength, elongation at break and hardness) was tested. Thermal behavior of prepared novel polycarbonate-based polyurethanes was investigated using differential scanning callorimetry (DSC). It was determined that the elastomer which contains the highest amount of urethane groups in its structure (TS content of 42 wt. %) exhibits the most pronounced phase separation and the highest degree of crystallinity. All prepared polyurethanes exhibit high elongation at break (over 700%). The glass transition temperature Tg of prepared samples was in the temperature region from ?39 to ?36?C, and it was found to be slightly influenced by the soft segment content. The enthalpy of chain segments relaxation in diffused region between hard and soft domains (detected in the temperature range from 35 to 55 ?C) was decreased with the increase of hard segment content. The multiple melting of hard segments (connected with the dissruption of physical crosslinks) appeared above 100 ?C. It was found that the melting enthalpy linearly increases with the increase of urethane group content. Sample with 42 wt. % of TS has the highest value of melting enthalpy (41.5 J/g).

Organo-catalyzed synthesis of aliphatic polycarbonates in solvent-free conditions

Download options Please wait... Article information DOI https://doi.org/10.1039/C2PY20056B Article type Paper Submitted 03 Feb 2012 Accepted 07 Mar 2012 First published 11 Apr 2012 Download Citation Polym. Chem., 2012,3, 1475-1480 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Organo-catalyzed synthesis of aliphatic polycarbonates in solvent-free conditions P. U. Naik, K. Refes, F. Sadaka, C. Brachais, G. Boni, J. Couvercelle, M. Picquet and L. Plasseraud, Polym. Chem., 2012, 3, 1475 DOI: 10.1039/C2PY20056B To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Social activity Tweet Share Search articles by author Prashant U. Naik Karima Refes Faten Sadaka Claire-Hélène Brachais Gilles Boni Jean-Pierre Couvercelle Michel Picquet Laurent Plasseraud

Synthesis and polymerization of alkyl halide-functional cyclic carbonates

To increase the diversity in functional aliphatic polycarbonates, a series of novel chloro- and bromo-functional six-membered cyclic carbonate monomers were synthesized. Despite asymmetry in the monomer functionalities, homopolymerization of the monomers afforded semicrystalline polycarbonates with a high tendency to crystallize from the melt and/or on precipitation from a THF solution. Melting points were found in the 90–105 °C or 120–155 °C range for polymers comprising methyl or ethyl moieties, respectively, in the backbone. The monomers were further copolymerized with trimethylene carbonate to form random copolymers. Even among some of these random copolymers elements of semicrystallinity were found as confirmed by melting endotherms in DSC. The results clearly show that the incorporation of alkyl halide functionalities in aliphatic polycarbonates may lead to materials with a high ability to form crystallites, even in random copolymers, likely driven by polar interactions due to the presence of the halide functionalities.

Cyclic carbonates as monomers for phosgene- and isocyanate-free polyurethanes and polycarbonates

Polyurethanes and polycarbonates are widely used in a variety of applications including engineering, optical devices, and high-performance adhesives and coatings, etc., and are expected to find use also in the biomedical field owing to their biocompatibility and low toxicity. However, these polymers are currently produced using hazardous phosgene and isocyanates, which are derived from the reaction between an amine and phosgene. Extensive safety procedures are required to prevent exposure to phosgene and isocyanate because of its high toxicity. Therefore, the demand for the production of isocyanate-free polymers has now emerged. Among the alternative greener routes that have been proposed, a popular way is the ring-opening polymerization (ROP) of cyclic carbonate in bulk or solution, usually using metallic catalyst, metal-free initiator, or biocatalyst. This review presents the recent developments in the preparation and application of cyclic carbonates as monomers for ROP, with emphasis on phosgene- and isocyanate-free polymerization to produce aliphatic polycarbonates and polyurethanes and their copolymers.

Improving the thermal and mechanical properties of poly(propylene carbonate) by incorporating functionalized graphite oxide

AbstractPoly(propylene carbonate) (PPC) is a new biodegradable aliphatic polycarbonate. However, the poor thermal stability, low glass transition temperatures (Tg), and relatively low mechanical property have limited its applications. To improve the thermal and mechanical properties of PPC, functionalized graphite oxide (MGO) was synthesized and mixed with PPC by a solution intercalation method to produce MGO/PPC composites. A uniform structure of MGO/PPC composites was confirmed by X‐ray diffraction and scanning electron microscope. The thermal and mechanical properties of MGO/PPC composites were investigated by thermal gravimetric analysis, differential scanning calorimetric, dynamic mechanical analysis, and electronic tensile tester. Due to the nanometer‐sized dispersion of layered graphite in polymer matrix, MGO/PPC composites exhibit improved thermal and mechanical properties than pure PPC. When the MGO content is 3.0 wt %, the MGO/PPC composites shows the best thermal and mechanical properties. These results indicate that nanocomposition is an efficient and convenient method to improve the properties of PPC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Lipase-mediated synthesis of six-membered cyclic carbonates from trimethylolpropane and dialkyl carbonates: Influence of medium engineering on reaction selectivity

Six-membered cyclic carbonates are potential monomers for aliphatic polycarbonates and polyurethanes in a process without using toxic phosgene and isocyanate. Lipase catalyzed transesterification of the polyol, trimethylolpropane (TMP) with dimethyl carbonate (DMC) or diethyl carbonate (DEC) followed by thermal cyclization was used for synthesis of six-membered cyclic carbonates with pendant hydroxyl and alkoxycarbonyloxyl groups. Immobilized lipase B from Candida antarctica (Novozym (R) 435) was used as the catalyst. Mixture of a hydrophilic solvent such as THF for high solubility of TMP, and a hydrophobic solvent such as toluene, were selected as the best solvent system for achieving high substrate conversion and selectivity. A relationship between polyol conversion and solvent hydrophobicity (log P) and solvent type, respectively, was established. THF:toluene system at a ratio of 0.5:1.0 (v/v) provided high degree of TMP conversion to product with high proportion of cyclic carbonates (>80%). The cyclic carbonate with pendant hydroxyl group was obtained with almost 85% selectivity at TMP conversion of 68.6% using 10% (w/w)Novozym (R) 435 at TMP:DMC ratio of 1:1. However, at TMP:DMC ratio of 1:5 and the same biocatalyst concentration, the TMP conversion was 100% with 72% selectivity for the cyclic carbonate with pendant alkoxycarbonyloxyl group. The product formed was without or with less content of linear carbonates, bis and tris(methoxycarbonyloxy)-TMP, as compared to that in a solvent-free system. The reactivity of DEC was lower than that of DMC. The reaction pathway leading to the formation of cyclic carbonate in this process comprised enzymatic carbonation of TMP with alkylcarbonates and thermal cyclization of linear carbonates. The process affords high degree of conversion of polyol to cyclic carbonates and provides a potentially attractive synthetic route for monomers of polycarbonates and polyurethanes. (C) 2011 Elsevier B.V. All rights reserved. (Less)

Synthesis, Characterization and Degradation of Novel Biodegradable Poly(butylene-co-hexamethylene carbonate) Copolycarbonates

A series of high molecular weight poly(butylene-co-hexamethylene carbonate) (PBHC) copolycarbonates were synthesized by copolymerizations of dimethyl carbonate (DMC), 1,4-butanediol (BD) and 1,6-hexanediol (HD) via a two-step melt polycondensation method. Microstructure analysis determined by high-resolution 13C-NMR showed that butylene carbonate (BC) units and hexamethylene carbonate (HC) units of the synthesized copolymers take a random distribution along the polymer chains. Analyses of the formed byproducts indicated that sublimation of oligomer and thermal degradation of polymer happen during the aliphatic polycarbonate polycondensation. The thermal properties and crystalline structure of the copolymers were studied by DSC, TGA and WAXD. WAXD patterns showed that the copolymers with 11 and 91 mol% HC units form poly(butylene carbonate) (PBC) and poly(hexamethylene carbonate) (PHC) crystals, respectively, while the three other copolymers with intermediate HC unit contents are completely amorphous. The results indicated that the BC and HC units are incompatible in each crystal lattice, and that cocrystallization cannot take place. TGA results indicated that the thermal stability of the obtained PBHC random copolymers is higher than that of PBC and increases with increasing the HC unit content. The enzymatic degradation study revealed that the biodegradation rate of the PBHC copolymers mainly depends not only on the degree of crystallinity and melting temperature but also on the type of crystalline structure, while the composition and microstructure dependences of biodegradability are negligible.

Preparation and properties of poly(propylene carbonate maleate) microcapsules for controlled release of pazufloxacin mesilate

AbstractA novel biodegradable aliphatic polycarbonate, poly(propylene carbonate maleate) (PPCMA) was synthesized by terpolymerization of carbon dioxide, propylene oxide, and maleic anhydride (MA), using a polymer supported bimetallic complex as catalyst. The utility of PPCMA to encapsulate and control the release of drug pazufloxacin mesilate (PZFX), via microcapsules, was investigated. PPCMA microcapsules containing PZFX were elaborated by solvent evaporation method based on the formation of double W/O/W emulsion. The manufacturing parameters such as the volume ratio of V(PPCMA) : V(PZFX), the concentration of stabilizer gelatin in outer aqueous phase played major roles on microcapsule characters, and were altered to optimize the process parameters. The PPCMA‐PZFX microcapsules were obtained with smooth and spherical surface under optimum condition, the mean diameter of microcapsules was ∼ 2 μm, and the drug loading and drug encapsulation efficiency of the microcapsules were 22.9 ± 1.05% and 82.1 ± 2.03%, respectively. PZFX released from PPCMA microcapsules was found to reach 89.8 ± 2.89% after 36d in a pH 7.4 phosphate‐buffered solution, and the release profile obeyed the Higuchi equation. The results suggest that the new polymer PPCMA provides an alternative to degradable matrix polymers for long‐term sustained releasing drug delivery systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Preparation and Characterization of Poly(propylene carbonate)/Alkali Lignin Composite Sheets by Calendering Process

PPC is a new biodegradable aliphatic polycarbonate with poor thermal stability and mechanical properties which is difficult to form sheets or films and so on. Through the addition of alkali lignin, thermal stability and mechanical properties of PPC was improved largely. PPC/ alkali lignin sheets could be prepared. DSC results showed that the thermal stability of PPC was improved by the introduction of alkali lignin. SEM showed good dispersion of alkali lignin particles into PPC matrix that resulted in good miscibility. Improved mechanical properties and thermal stability of PPC/ alkali lignin blends were attributed to stronger interfacial interaction of PPC and alkali lignin. These results indicate that blending PPC with alkali lignin is an efficient and convenient method to improve the properties of PPC.

Laser-induced breakdown spectroscopy for polymer identification

This study aims at differentiating several organic materials, particularly polymers, by laser induced breakdown spectroscopy. The goal is to apply this technique to the fields of polymer recycling and cultural heritage conservation. We worked with some usual polymers families: polyethylene (PE), polypropylene (PP), polyoxymethylene, (POM), poly(vinyl chloride), polytetrafluoroethylene, polyoxyethylene (POE), and polyamide for the aliphatic ones, and poly(butylene terephthalate), acrylonitrile-butadiene-styrene, polystyrene, and polycarbonate for the aromatic ones. The fourth harmonic of a Nd:YAG laser (266 nm) in ambient air at atmospheric pressure was used. A careful analysis of the C(2) Swan system (0,0) band in polymers containing no C-C (POM), few C-C (POE), or aromatic C-C linkages led us to the conclusion that the C(2) signal might be native, i.e., the result of direct ablation from the sample. With use of these results, aliphatic and aromatic polymers could be differentiated. Further data treatments, such as properly chosen line ratios, principal component analysis, and partial least squares regression, were evaluated. It was shown that many polymers could be separated, including PE and PP, despite their similar chemical structures.

Syntheses of Aliphatic Polycarbonates from 2′-Deoxyribonucleosides

Poly(2'-deoxyadenosine) and poly(thymidine) constructed of carbonate linkages were synthesized by polycondensation between silyl ether and carbonylimidazolide at the 3'- and 5'-positions of the 2'-deoxyribonucleoside monomers. The N-benzoyl-2'-deoxyadenosine monomer afforded the corresponding polycarbonate together with the cyclic oligomers. However, the deprotection of the N-benzoyl group resulted in the scission of the polymer main chain. Thus, the N-unprotected 2'-deoxyadenosine monomers were examined for polycondensation. However, there was involved the undesired reaction between the adenine amino group and the carbonylimidazolide to form the carbamate linkage. In order to exclude this unfavorable reaction, dynamic protection was employed. Strong hydrogen bonding was used in place of the usual covalent bonding for reducing the nucleophilicity of the adenine amino group. Herein, 3',5'-O-diacylthymidines that form the complementary hydrogen bonding with the adenine amino group were added to the polymerization system of the N-unprotected 2'-deoxyadenosine monomer. Consequently, although the oligomers (M(n) = 1000-1500) were produced, the contents of the carbamate group were greatly reduced. The dynamic protection reagents were easily and quantitatively recovered as the MeOH soluble parts from the polymerization mixtures. In the polycondensation of the thymidine monomer, there tended to be involved another unfavorable reaction of carbonate exchange, which consequently formed the irregular carbonate linkages at not only the 3'-5' but also the 3'-3' and 5'-5' positions. Employing the well-designed monomer suppressed the carbonate exchange reaction to produce poly(thymidine) with the almost regular 3'-5'carbonate linkages.

Aliphatic Polycarbonates Produced from the Coupling of Carbon Dioxide and Oxetanes and Their Depolymerization via Cyclic Carbonate Formation

The (salen)CrCl/onium salt catalyzed coupling reactions of several oxetane derivatives and carbon dioxide are reported. The oxetanes investigated contain substituents in the 3-position covering a range of steric requirements. The oxetanes examined include, 3,3-dimethyloxetane, 3-methoxymethyl-3-methyloxetane, and 3-benzyloxymethyl-3-methyloxetane. The rates of reaction of these oxetanes with CO2 were found to be significantly slower than the corresponding process with the parent oxetane monomer. Furthermore, in these instances the formation of copolymer was found to proceed via the preformed cycloaddition product, i.e., the six-membered cyclic carbonate, to a greater extent and increasing with the steric bulk of the substituents on oxetane. For these sterically more hindered oxetanes, the CO2 coupling reaction carried out in toluene at 110 °C reached an equilibrium product distribution of copolymer to cyclic carbonate which increased in cyclic carbonate product with increasing steric requirements of the oxetane monomer. For example, the catalyzed coupling of the parent oxetane and CO2 provides a copolymer to cyclic carbonate ratio of greater than 95%, whereas the corresponding product distribution for 3-benzyloxymethyl-3-methyloxetane was observed to be 60%. The catalytic rate of depolymerization of a purified sample of the copolymer afforded from 3-benzyloxymethyl-3-methyloxetane and CO2 to the corresponding cyclic carbonate, 5-benzyloxymethyl-5-methyl-1,3-dioxan-2-one, was found to be greatly retarded when carried out in an atmosphere of CO2.

High‐molecular‐weight aliphatic polycarbonates by melt polycondensation of dimethyl carbonate and aliphatic diols: synthesis and characterization

AbstractAliphatic polycarbonates (APCs) synthesized by polycondensation of dialkyl carbonates and aliphatic diols have often been used as precursors for the preparation of novel polyurethanes. However, they could not be applied in plastics directly because of poor mechanical properties caused by low molecular weight. In the work reported in this paper, three kinds of fairly high molecular weight (Mw ≥ 166 000 g mol−1) APCs with narrow dispersity ($\rlap{-}{D} \leq 1.86$) were successfully synthesized via a successive two‐step polycondensation of dimethyl carbonate and diols, using a novel TiO2/SiO2‐based catalyst. This process gave a high yield of above 85%. 1H NMR spectra indicated that there was no detectable decarboxylation happening during polycondensation at high temperature. The effects of molecular weight on the mechanical properties of the APCs are discussed. APCs with Mw greater than 70 000 g mol−1 showed useful mechanical properties. Especially, poly(butylene carbonate) and poly(hexamethylene carbonate) exhibited excellent tensile strengths of 34.1 and 40.0 MPa, respectively, when their Mw was ca 170 000 g mol−1. All the APCs showed appreciable biodegradability under enzymatic degradation. Copyright © 2011 Society of Chemical Industry

Chain Growth and Branch Structure Formation during Lipase-Catalyzed Synthesis of Aliphatic Polycarbonate Polyols

This study explored Candida antarctica Lipase B (CALB)-catalyzed condensation reactions to prepare high-purity, metal-free, polycarbonate polyols. Terpolymerizations of diethyl carbonate (D) with 1,8-octanediol (O) and tris(hydroxymethyl)ethane (T) were performed in bulk at relatively low temperature (80 °C) using a pressure-varied two-stage process to minimize evaporative loss of diethyl carbonate. NMR experiments of resulting polycarbonate polyols, including analysis of proton NMR resonances by COSY spectra and carbon-13 resonances by HSQC, HSQC-TOCSY, and HMBC spectra, allowed determination of copolymer composition as well as relative percentages of linear, terminal, and dendritic T-units. With D/O/T monomer feed ratio 3:0.9:0.1, the highest values of dendritic T-unit content (83%) and Mw (23 900) by SEC-MALLS were attained. By decreasing D content in the monomer feed, the mol % of dendritic T-units in chains decreased to as low as 0%. By keeping the D/(O + T) ratio constant at 2.0 while increasing the...

Functionalized cyclic carbonates: from synthesis and metal-free catalyzed ring-opening polymerization to applications

Aliphatic polycarbonates are often referenced for their interesting applications due to their lower tendency to undergo hydrolysis, lower Tg, and their degradation in renewable resources. Their synthesis is described using a series of metal-free catalysts allowing preparation of well-defined polymers in terms of molecular weights and structures. Additionally, some highlights regarding their biomedical applications such as drug targeting are presented.

Aliphatic polycarbonates and poly(ester carbonate)s from fatty acid derived monomers

Fatty acid derivatives were efficiently used as starting materials for the synthesis of polycarbonates and poly(ester carbonate)s. A novel AB-type self-condensable monomer, ethyl(9-hydroxy-10-methoxyoctadecyl)carbonate (EHMOC) and a dicarbonate monomer, 4-[(ethoxycarbonyl)oxy]butyl-12-[(ethoxycarbonyl)oxy]octadec-9-enoate (EOBEOE) were prepared from oleyl alcohol and ricinoleic acid, respectively. Of these, EHMOC was polymerized by the alcohol–carbonate exchange self-polycondensation approach, while EOBEOE was polycondensed with various biobased diols to give polycarbonates and poly(ester carbonate)s, respectively. The monomers and polymers were well characterized by FTIR and 1H-NMR spectroscopy. The 13C-NMR spectroscopy revealed the formation of randomly distributed sequences in the poly(ester carbonate)s due to the carbonate interchange reaction. An unexpected formation of polyricinoleate was observed and confirmed by NMR and MALDI-TOF spectroscopy. Most of the polymers displayed good thermal stability with the temperature at 10% weight loss in the range 273–325 °C. Due to the presence of aliphatic segments, these materials exhibit very low glass transition temperature.