Polymerization Of Trimethylene Carbonate Research Articles

Organocatalytic synthesis of temperature-sensitive degradable PNiPAAm- b-PTMC block copolymers and micellar characterizations

Amphiphilic PNiPAAm- b-PTMC were synthesized by ring-opening polymerization of trimethylene carbonate (TMC) initiated by hydroxyl-terminated poly( N-isopropylacrylamide) (PNiPAAm) as the macroinitiator with the organocatalyst 1,5,7-triazabicyclo-[4.4.0]dec-5-ene (TBD). PNiPAAm- b-PTMC solutions had lower critical solution temperature (LCST) that depended on polymer composition and the solution media. The block copolymers form micelles in the aqueous phase with core–shell structure. Transmission electron microscopy analysis of micelle morphology revealed a spherical structure. Observations and determinations show high drug entrapment efficiency and drug-loading content for these drug micelles.

Ring‐opening polymerization of trimethylenecarbonate by the bridged diphenoxo ytterbium (II) complex

AbstractA novel ytterbium (II) complex 2 supporting by a bridged bisphenolate ligand H2LOC4H7 (L = C4H7OCH2N(CH2‐2‐OC6H2‐3,5‐Bu)2) with a tetrahydrofuran donor on side‐arm was synthesized in high yield and characterized by elementary analysis, IR, 1H‐NMR, and 13C‐NMR. Ring‐opening polymerization of 1,3‐trimethylenecarbonate (TMC) was carried out using complex 2 and a known complex [Me2NCH2CH2N(CH2‐2‐O‐3,5‐C6H2(But)2)2]Yb 1 as the initiators, respectively. It was found that both complexes 1 and 2 can alone initiate the ring‐opening polymerization of TMC, and complex 1 showed higher activity than complex 2. The activity of both complexes 1 and 2 was found to be higher than that of monodentate phenoxo ytterbium (II) complex (2,6‐Bu‐C6H3O)2Yb(THF)3. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Poly(carbonate-urethane): an isocyanate-free procedure from α,ω-di(cyclic carbonate) telechelic poly(trimethylene carbonate)s

A simple isocyanate-free method to synthesize poly(trimethylene carbonate hydroxy-urethane)s is described. The strategy first involves the synthesis of α,ω-di(cyclic carbonate) telechelic polycarbonate precursors upon ring-opening polymerization of trimethylene carbonate using a cyclic carbonate alcohol as chain transfer agent, followed by the ring-opening polyaddition of the terminal cyclic carbonate with a diamine. Such poly(carbonate-hydroxyurethane)s exhibit macromolecular carbonate segments of tunable length/molar mass.

Ring-Opening Polymerization of Trimethylene Carbonate Catalyzed by Methanesulfonic Acid: Activated Monomer versus Active Chain End Mechanisms

The ring-opening polymerization (ROP) of trimethylene carbonate (TMC) initiated by water or n-pentanol and catalyzed by trifluoromethanesulfonic acid (HOTf) or methanesulfonic acid (MSA) has been investigated. In contrast with HOTf, MSA was found to afford poly(trimethylene carbonate) (PTMC) free of ether linkages even under forcing conditions. The comparison of the two acids substantiates further that activity does not simply correlate with acidity. Analysis of the resulting PTMC by Size Exclusion Chromatography (SEC), 1H NMR spectroscopy and mass spectrometry revealed the absence of molar mass control due to the formation of two polymer populations. This phenomenon was unambiguously attributed to the occurrence of two competitive mechanisms, namely Activated Monomer (AM) and Active Chain End (ACE). Such a situation is frequently encountered in the ROP of cyclic ethers, but is unprecedented for cyclic carbonates. Its deleterious impact on the polymerization control can be significantly reduced by maintai...

Metal Triflates as Highly Stable and Active Catalysts for the “Immortal” Ring‐Opening Polymerization of Trimethylene Carbonate

AbstractThe controlled “immortal” ring‐opening polymerization of trimethylene carbonate (TMC) using a two‐component catalyst system based on a metal Lewis acid, such as a metal triflate M(OTf)n (M=Ca, Sc, Zn, Al, Bi; OTf=CF3SO3−) or the metallic salt Fe(acac)3, (acac=acetylacetonate) and an alcohol (ROH) as co‐initiator and chain‐transfer agent, is carried out in bulk at 110–150 °C. As a result of the water‐tolerance of these systems, experimental operating conditions do not require any special care. The approach, valorized both with various ROH transfer agents and with either purified or unpurified monomer sources, is highly versatile. Functional telechelic polycarbonates HPTMCOR, devoid of decarboxylation sequences, are obtained [PTMC=poly(trimethylene carbonate)]. The molar mass of the PTMCs can be readily predicted by a simple model, taking into account the [TMC]0/[ROH]0 ratio and the amount of transferring impurities present in the raw/unpurified reagents. Such simple, air‐ and moisture‐robust catalytic systems, which display quite high activities (TOF up to 28 200 h−1) and productivities (TON up to 45 000) are thus extremely valuable, especially industrially. The performances of these systems are described in comparison to the previously established valuable inorganic and organometallic catalytic systems, namely metal amido complexes ([M{N(SiMe3)2}3]) and [(BDI)Zn{N(SiMe3)2}] (BDI=β‐diiminate ligand) derivatives.

Polymerization of trimethylene carbonate in aqueous solutions: Reaction mechanism and characterization

AbstractPolymerization of a trimethylene carbonate (TMC) in an aqueous solution was investigated by gel permeation chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance. The polymerization reaction proceeded rapidly in the aqueous solution and high conversion was achieved in a relatively short time. 1,3‐Propanediol (PPD) formed by hydrolysis of TMC was used as the initiator. The TMC oligomer obtained by ring‐opening polymerization had a TMC unit backbone with terminal 3‐hydroxypropyl groups at both chain ends. The oligomer underwent transesterification reaction with elimination of PPD, resulting in a gradual increase in the molecular weight of the product. The molecular weight was affected by the concentration of TMC. The thermal properties of the polymers were investigated by differential scanning calorimetry. Polymers within the molecular weight (Mn) range from 6.0 × 103 to 2.3 × 104 g/mol crystallized, and endothermic peaks corresponding to the melting temperature were observed. The glass transition temperature increased with the molecular weight of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1485–1492, 2010

Polimery syntetyczne i naturalne w nowoczesnych materialach wielkoczasteczkowych. Cz. I. Polimery z surowcow odnawialnych i nanokompozyty polimerowe

A series of poly(ester-carbonate-urethane)s containing different weight ratios of respective fragments were synthesized by coupling of dihydroxyl compounds with diisocyanates. First, poly(trimethylene carbonate) diol (PTMCD) was prepared via ring opening polymerization of trimethylene carbonate (TMC) using 1,4-butanediol as an initiator and stannous 2-ethylhexanoate as a catalyst. PTMCD was further reacted in the melt with polyester polyol (dimer diol derived from dimerized fatty acid, DD) in the presence of hexamethylene diisocyanate (HDI) as a coupling agent. The structure and physical properties of PTMCD and final copolymer were characterized by ATR FT-IR and DSC measurements. Thermal analysis indicated that temperature transitions were dependent on the copolymer composition. The hydrolytic degradation (pH=9.0) profiles of selected copolymers were also dependent on the polymer composition: higher weight loss was observed for polymers containing higher amount of carbonate units. At high concentration of DD (70 wt. %) the polymers showing high elasticity (330%) were produced.

Fabrication of biodegradable poly(trimethylene carbonate) networks for potential tissue engineering scaffold applications

AbstractBiodegradable poly(trimethylene carbonate) (PTMC) networks were prepared by photopolymerization of linear (L)‐ and star (S)‐shaped PTMC macromonomers for potential tissue engineering scaffold applications. The L‐ (Mn, 6400) and S‐shaped (Mn, 5880) PTMC macromonomers were synthesized using 1,4‐butane diol and 2‐ethyl‐ 2‐hydroxyl‐propane‐1,3‐diol co‐initiated ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of stannous octoate and subsequent acrylation with acryloyl chloride. Chemical structures of the PTMC macromonomers and their corresponding networks were characterized by 1H NMR and 13C NMR spectroscopy. The human endothelial cell line, EA.hy926 was used to test the biocompatibility, cell adhesion, and proliferation behavior of both PTMC networks. The PTMC networks made from the S‐shaped macromonomers exhibited superior cell adhesion and proliferation behavior than those made of the linear macromonomers. Copyright © 2008 John Wiley & Sons, Ltd.

Ultraproductive, Zinc‐Mediated, Immortal Ring‐Opening Polymerization of Trimethylene Carbonate

Ultraproductive, Zinc‐Mediated, Immortal Ring‐Opening Polymerization of Trimethylene Carbonate

Zinc lactate‐catalyzed ring‐opening polymerization of trimethylene carbonate under microwave irradiation

AbstractMicrowave‐assisted ring‐opening polymerization (MROP) of trimethylene carbonate (TMC) was carried out with four different types of zinc lactate, as the catalyst. Poly(trimethylene carbonate)s (PTMC) with a number–average molar mass ranging from 2990 to 75,410 g/mol and a TMC conversion ranging from 85.2% to 98.2% were synthesized effectively in 30 min at 120°C under microwave irradiation. The effects of the catalyst type, catalyst concentration, and microwave irradiation time on the MROP of TMC were studied. The MROP of TMC was much faster than that under conventional heating conditions. Thermal analysis suggested that PTMC with higher molar mass exhibited higher glass transition temperature (Tg) and thermal stability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Ring-Opening Polymerization of Cyclic Monomers by Complexes Derived from Biocompatible Metals. Production of Poly(lactide), Poly(trimethylene carbonate), and Their Copolymers

Tridentate Schiff base calcium derivatives have been prepared and shown to be very effective catalysts for ring-opening polymerization of both lactides and trimethylene carbonate to produce high molecular weight polymers with narrow polydispersity. Optimization of the calcium catalyst was achieved changing the imine backbone, initiator, and substituent on the phenolate ring of the calcium complex. Turnover frequencies were obtained up to 1124 h−1 for a melt polymerization of l-lactide carried out at 110 °C. Solution studies in CDCl3 demonstrated the polymerization reaction is first order in [monomer] and [catalyst], with k = 19.9 M−1 h−1 for lactide polymerization and k = 500.0 M−1 h−1 for trimethylene carbonate polymerization at ambient temperature. The activation parameters for the ring-opening polymerization of l-lactide using catalyst 1a were determined to be ΔH⧧ = 73.5 ± 3.8 kJ/mol and ΔS⧧ = −42.5 ± 12.6 J/(mol K), and catalyst 1a was shown to produce heterotactic polylactide from rac-lactide with a Pr value of 0.73. It was also found that the ring-opening polymerization of trimethylene carbonate is a lower energy process than that of lactide polymerization as revealed by its activation parameters, which were determined to be ΔH⧧ = 37.9 ± 3.1 kJ/mol and ΔS⧧ = −135.1 ± 11.4 J/(mol K). Furthermore, this class of catalysts afforded from biocompatible metals is very effective at producing diblock copolymer from trimethylene carbonate and lactides. Kinetic studies of the copolymerization of trimethylene carbonate and l-lactide are presented as a function of the feed ratio of the two cyclic monomers.

Mechanistic Studies of the Copolymerization Reaction of Oxetane and Carbon Dioxide to Provide Aliphatic Polycarbonates Catalyzed by (Salen)CrX Complexes

Chromium salen derivatives in the presence of anionic initiators have been shown to be very effective catalytic systems for the selective coupling of oxetane and carbon dioxide to provide the corresponding polycarbonate with a minimal amount of ether linkages. Optimization of the chromium(III) system was achieved utilizing a salen ligand with tert-butyl groups in the 3,5-positions of the phenolate rings and a cyclohexylene backbone for the diimine along with an azide ion initiator. The mechanism for the coupling reaction of oxetane and carbon dioxide has been studied. Based on binding studies done by infrared spectroscopy, X-ray crystallography, kinetic data, end group analysis done by (1)H NMR, and infrared spectroscopy, a mechanism of the copolymerization reaction is proposed. The formation of the copolymer is shown to proceed in part by way of the intermediacy of trimethylene carbonate, which was observed as a minor product of the coupling reaction, and by the direct enchainment of oxetane and CO 2. The parity of the determined free energies of activation for these two processes, namely 101.9 kJ x mol (-1) for ring-opening polymerization of trimethylene carbonate and 107.6 kJ x mol (-1) for copolymerization of oxetane and carbon dioxide supports this conclusion.

Development of Three-Dimensional Alginate Encapsulated Chondrocyte Hybrid Scaffold Using Microstereolithography

Hydrogels are useful materials because of their chemical similarity to extracellular matrix and their ability to rapidly diffuse hydrophilic nutrients and metabolites. Using rapid prototyping methods, we fabricated freeform three-dimensional (3D) scaffolds with chondrocytes encapsulated in an alginate hydrogel. The 3D hybrid scaffold was developed as combination of two components, a trimethylene carbonate (TMC)/trimethylolpropane (TMP) framework and an alginate hydrogel within an encapsulation of chondrocytes. To develop 3D hybrid scaffolds, we employed a microstereolithography system. The biodegradable, photopolymerizable liquid prepolymer was prepared by the polymerization of TMC with TMP and subsequently end capped with an acrylate group. The meshed framework of scaffolds withstood mechanical loading effectively. The line depth and linewidth could be controlled by varying laser power, scan path, and scan speed. Results of cell culture indicate that the biomimetic nature of these encapsulated chondrocyte scaffolds effectively retain the phenotypic function of chondrocytes within the scaffold structure. The proposed 3D hybrid scaffolds can be used for cartilage regeneration.

Precise preparation of four-arm-poly(ethylene glycol)-block-poly(trimethylene carbonate) star block copolymers via activated monomer mechanism and examination of their solution properties

The polymerization of trimethylene carbonate (TMC) in the presence of HCl·Et2O via activated monomer mechanism was performed to synthesize 4a-PEG-b-PTMC star block copolymers composed of poly(ethylene glycol) (PEG) and poly(trimethylene carbonate) (PTMC) using four-arm (4a) PEG as an initiator. The TMC conversion and molecular weight of PTMC increased linearly with the polymerization time or the feed ratios of the TMC to 4a-PEG in the presence of HCl·Et2O in CH2Cl2 at 25°C. The obtained PTMC had molecular weights close to the theoretical value calculated from TMC to PEG molar ratio and exhibited monomodal GPC curve. We prepared successfully 4a-PEG-b-PTMC star block copolymers without metal catalyst at room temperature via living ring-opening polymerization (ROP) of TMC from 4a-PEG as an initiator in the presence of HCl·Et2O as a monomer activator. The CMCs of the 4a-PEG-b-PTMC star block copolymers determined from fluorescence measurements. The CMCs of the 4a-PEG-b-PTMC star block copolymers decreased in the order of the increase in the PTMC segment. The partition equilibrium constant, Kv, which is an indicator of the hydrophobicity of the micelles of the 4a-PEG-b-PTMC star block copolymers in aqueous media, increased with the increase in the PTMC segment. In conclusion, we confirmed that the 4a-PEG-b-PTMC star block copolymers form micelles and hence may be potential hydrophobic-drug delivery vehicles.

Microwave‐assisted ring‐opening polymerization of trimethylene carbonate in the presence of ionic liquid

AbstractMicrowave‐assisted ring‐opening polymerization (MROP) of trimethylene carbonate in the presence of 1‐n‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim]BF4) ionic liquid was investigated. In the presence of 5 wt % [bmim]BF4, poly (trimethylene carbonate) (PTMC) with a number‐average molar mass (Mn) of 36,400 g/mol was obtained at 5 W for only 60 min. The Mn of PTMC synthesized in the presence of [bmim]BF4 was much higher than that produced in bulk at the same reaction time. In addition, compared with those produced by conventional heating, the Mn of PTMC and monomer conversion by MROP with or without [bmim]BF4 were both higher. Thermal properties of the resulting PTMC were characterized by differential scanning calorimetry. Under microwave irradiation in the presence of ionic liquid, the polymerization could be carried out efficiently and effectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5857–5863, 2007

Polymeric nano-micelles as drug carrier using polyethylene glycol and polytrimethylene carbonate linear and star-shaped block copolymer

Abstract The polymerization of trimethylene carbonate (TMC) in the presence of HCl · Et2O via activated monomer mechanism was performed to synthesize linear and star-shaped block copolymers composed of polyethyleneglycol (PEG) and poly(trimethylene carbonate) (PTMC). The obtained PTMCs had molecular weights close to the theoretical values calculated from the TMC to PEG molar ratios and exibited monomodal GPC curves. We successfully prepared PEG and PTMC linear and star-shaped block copolymers by activated monomer mechanism. The characterization for formation of micelle of block copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering (DLS), AFM and fluorescence techniques (FL). The block copolymers gave micelles with a critical micelle concentration (CMC) ranging 1.88 × 10−2–3.09 × 10−3 mg/mL depended on the molecular shape of block copolymers. The diameters of micelles, measured by DLS, were 100–250 nm. Most micelles exhibited a spherical shape in AFM.

Rapid synthesis of poly(trimethylene carbonate) by microwave-assisted ring-opening polymerization

Poly(trimethylene carbonate) (PTMC) was synthesized successfully by microwave-assisted ring-opening polymerization of trimethylene carbonate. The polymerizations were carried out in a single-mode microwave oven using ethylene glycol (EG) as the initiator in the absence of any metallic compound catalyst. The temperature–time profiles of the reaction mixture were investigated at different power levels and EG concentrations. The molar mass of the resulting PTMC and TMC monomer conversion by the microwave method is higher than those by the conventional method. Thermal properties of the resulting polymers were studied by differential scanning calorimetry. Microwave irradiation proved to be an effective and efficient method for the preparation of PTMC.

Ring‐opening polymerization of trimethylenecarbonate and its copolymerization with ϵ‐caprolactone by lanthanide (II) aryloxide complexes

AbstractLanthanide metal (II) 2,6‐di‐tert‐butylphenoxide complexes (ArO)2Ln(THF)3 (Ln = Sm 1, Yb 2) alone have been developed to catalyze the ring‐opening polymerization of trimethylenecarbonate (TMC) and random copolymerization of TMC and ε‐caprolactone (ε‐CL) for the first time. The influence of reaction conditions, such as initiator, initiator concentration, polymerization temperature, and polymerization time, on monomer conversion, molecular weight, and molecular weight distribution of the resulting PTMC was investigated. It was found that the divalent complex 1 showed higher activity for the polymerization of TMC than complex 2. The random structure and thermal behavior of the copolymers P(TMC‐co‐CL) have been characterized by 1H NMR, 13C NMR, GPC, and DSC analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Polymeric nano-micelles using poly(ethylene glycol) and poly(trimethylene carbonate) diblock copolymers as a drug carrier

The polymerization of trimethylene carbonate (TMC) in the presence of HCl·Et2O via activated monomer mechanism was performed to synthesize diblock copolymers composed of methoxy poly(ethylene glycol) (MPEG) and poly(trimethylene carbonate) (PTMC). The obtained PTMCs had molecular weights close to the theoretical values calculated from the TMC to MPEG molar ratios and exhibited monomodal GPC curves. We successfully prepared MPEG and PTMC diblock copolymers by activated monomer mechanism. The micellar characterization of MPEG–PTMC diblock copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering, AFM and fluorescence techniques. The diblock copolymers formed micelles with a critical micelle concentration (CMC) ranging 1.76×10−3 to 0.79×10−3mg/mL, depended on the hydrophobic block lengths of MPEG–PTMC copolymers. The diameters of micelles, measured by dynamic light scattering, were 150–360nm. Most micelles exhibited a spherical shape in AFM.

Unprecedented Polymerization of Trimethylene Carbonate Initiated by a Samarium Borohydride Complex: Mechanistic Insights and Copolymerization with ε‐Caprolactone

Poly(trimethylene carbonate) (PTMC) was synthesized through ring-opening polymerization by using a rare-earth borohydride initiator, [Sm(BH(4))(3)(thf)(3)]. This initiator shows a high activity to give high-molar-mass PTMCs with molar-mass distributions ranging from 1.2 to 1.4, and with a regular structure void of ether linkages. The polymers were characterized by (1)H and (13)C NMR spectroscopy, (1)H-(1)H COSY, (1)H-(13)C HMQC NMR spectroscopy, size-exclusion chromatography (SEC), viscosimetry, and MALDI-TOF MS analyses. A coordination-insertion mechanism was established based on detailed NMR characterizations, especially of the polymer chain end-functions. The monomer initially coordinates the samarium to give [Sm(BH(4))(3)(tmc)(3)], 1. The monomer then opens up through cleavage of the cyclic ester oxygen--acyl bond and inserts into the Sm--HBH(3) bond resulting in an alkoxide complex, [Sm{O(CH(2))(3)OC(O)HBH(3)}(3)], 2, or [Sm{O(CH(2))(3)OC(O)H}(3)], 2', which then propagates the polymerization of TMC to give the active polymer [Sm({O(CH(2))(3)OC(O)}(n)O(CH(2))(3)OC(O)HBH(3))(3)], 3 or [Sm(O(CH(2))(3)OC(O){O(CH(2))(3)OC(O)}(n)O(CH(2))(3)OC(O)H)(3)], 3'. Finally, acidic hydrolysis of 3 or 3' gives HO(CH(2))(3)OC(O)[O(CH(2))(3)OC(O)](n)O(CH(2))(3)OC(O)H, 4. This novel alpha-hydroxy,omega-formatetelechelic PTMC represents the first example of a formate-terminated polycarbonate. TMC and epsilon-caprolactone (CL) were copolymerized to afford both random PTMC-co-PCL and block PTMC-b-PCL copolymers that were characterized by (1)H NMR spectroscopy, SEC, and differential scanning calorimetry (DSC). The structure of the block copolymers depends on the order of addition of monomers: if CL is introduced first, dihydroxytelechelic HO-PTMC-b-PCL-OH polymers are formed, whereas introduction of TMC first or simultaneous addition of comonomers leads to hydroxyformatetelechelic HC(O)O-PTMC-b-PCL-OH analogues.