Telechelic Polyesters Research Articles

One-Step Upcycling the Engineering Plastic of Polyoxymethylene toward a Flowing Telechelic Polyester: From Poly(A) to Poly(A-alt-B)

One-Step Upcycling the Engineering Plastic of Polyoxymethylene toward a Flowing Telechelic Polyester: From Poly(A) to Poly(A-<i>alt</i>-B)

Synthesis of Polyesters Containing Long Aliphatic Methylene Units by ADMET Polymerization and Synthesis of ABA-Triblock Copolymers by One-Pot End Modification and Subsequent Living Ring-Opening Polymerization.

The synthesis of high-molecular-weight (Mn up to 62,000 g/mol) polyesters has been achieved by acyclic diene metathesis (ADMET) polymerization of α,ω-dienes prepared from biobased bis(undec-10-enoate) and diols [ethylene glycol (M1), propylene glycol (M2), 1,9-nonanediol (M3), 1,4-benzenedimethanol (M4), and hydroquinone (M5)] using ruthenium-carbene catalysts. Replacement of the solvent during the ADMET polymerization was effective for obtainment of the high-molecular-weight polymers (expressed as P1-P5). The melting temperatures (Tm) in the resultant polyesters were dependent upon the diol (middle) segment employed, and the polymer prepared from M5 exceeded 100 °C (a Tm value of 122.5 °C). The polymerization of M3 and M4 in the presence of 1,4-cis-diacetoxy-2-butene (DAB, as the chain transfer agent) afforded the telechelic polyesters [P3(OAc)2 and P4(OAc)2, respectively] containing acetoxy end groups exclusively. The resultant polymers containing hydroxy group termini [P3(OH)2 and P4(OH)2], prepared by the selective deprotection of the acetoxy end groups, were treated with AlEt3 followed by addition of ε-caprolactone to afford the ABA-type triblock copolymers exclusively, through a living ring-opening polymerization. The depolymerization (hydrolysis) under basic conditions (NaOH aqueous solution) of P3 was explored.

Short-Loop Chemical Recycling via Telechelic Polymers for Biobased Polyesters with Spiroacetal Units

Spirocyclic acetal structures have recently received growing attention in polymer science due to their dual potential to raise the glass transition temperature (Tg) and enable chemical recycling of biobased polymers. In the present work, a vanillin-based diol with a spirocyclic acetal structure was incorporated in a series of rigid amorphous polyesters based on neopentyl glycol and dimethyl terephthalate (DMT). Up to 50 mol % of spirocyclic diol (with respect to DMT) could be incorporated in the copolyesters, but a reasonably high molecular weight was only achieved when ≤30 mol % of the spirocyclic diol was used. The presence of the spiroacetal units in the polyesters not only enhanced the Tg (up to 103 °C) and thermal stability (T5 ≥ 300 °C) but also the oxygen barrier of solution-cast films. We found that the acetal units in the copolyesters could be selectively hydrolyzed under acidic conditions while virtually retaining all of the ester bonds in the polymer backbone. After acidic hydrolysis, telechelic polymers exclusively terminated by two aldehyde end groups were obtained. In this work, we have demonstrated that these telechelic polyesters can be conveniently converted back into poly(acetal-ester)s via cycloacetalization reactions with pentaerythritol.

ROP and crystallization behaviour of partially renewable triblock aromatic-aliphatic copolymers derived from L-lactide

Two series of partially biobased ABA triblock copolyesters were successfully prepared by ring-opening polymerization (ROP) of L-lactide initiated by two telechelic polyester polyols using an organic catalyst. B blocks were made of telechelic poly(hexamethylene terephthalate) (PHT) and poly(hexamethylene 2,5-furandicarboxylate) (PHF), respectively, with average molar masses of around 3500 g mol−1 and A blocks were made of poly(lactic acid)s (PLA) of different block lengths.For each series, four copolymers with different PHT/PLA and PHF/PLA compositions were prepared by varying the feed molar ratios. The triblock structure of the obtained copolymers was ascertained by 13C NMR, which confirms that the organic catalyst employed does not promote transesterification reactions at the low temperatures used for the reaction. All copolyesters were thermally stable under inert atmosphere up to around 300 °C. For all synthesized copolyesters, the PLA blocks were unable to crystallize, mainly due to racemization reactions taking place during L-lactide ROP. Both, PHT and PHF blocks were able to crystallize and their thermal and structural properties (Tm, Tc, Xc and lamellar thickness) were independent on PLA content until its concentration was very high and topological restrictions difficulted crystallization. According to SAXS, most copolymers were found to be miscible in the melt. Both PLA-b-PHT-b-PLA or PLA-b-PHF-b-PLA triblock copolymers showed a single Tg indicating that the components are miscible in the amorphous state.

Synthesis of telechelic polyesters by means of transesterification of an A2 + B2 polycondensation-derived cyclic polyester with a functionalized diester

End-functionalized linear polyesters were synthesized by means of base-catalyzed transesterification of a cyclic polyester, obtained by A2 + B2 polycondensation, with a symmetric functional diester as an exchange reagent.

Metal-free catalyzed ring-opening polymerization and block copolymerization of ω-pentadecalactone using amino-ended initiators

Metal-free catalysis was successfully applied to polymerize ω-pentadecalactone (PDL) by ring-opening polymerization (ROP) using several amino-ended initiators, namely hexylamine, allylamine and O,O′-bis(3-aminopropyl)diethylene glycol. This polymerization method was suitable to prepare telechelic polyesters carrying functional-end groups. The technique was then extended to the synthesis of block copolymers by ROP of PDL using bisamino-ended poly(ethylene glycol) (Mn = 2600) as macroinitiator. PPDLx-PEG56-PPDLx triblock copolymers with Mn ranging between ∼4000 and ∼90,000 g ·mol−1 were synthesized and extensively characterized by NMR, DSC, TGA and XRD. The amphiphilic copolymers thus produced were demonstrated to be able to self-assemble in nanoparticles with average diameters of ∼100–200 nm and morphologies highly depending on blocks lengths. The described synthetic route distinguishes in providing “clean” amphiphilic copolymers, which are attractive candidates for biomedical applications.

Hydroxyl-functionalized amphiphilic triblock copolyesters made of tartaric and lactic acids: Synthesis and nanoparticle formation

Bio-based triblock copolyesters were synthesized by ring-opening polymerization of l-lactide in solution using a hydroxyl-ended polytartrate as di-functional macroinitiator. This telechelic polyester with a Mn about 3000 g·mol−1 was obtained by non-stoichiometric melt polycondensation of dimethyl 2,3-di-O-isopropylidene-l-tartrate and 1,4-butanediol. Two symmetrical triblock copolyesters with Mn in the 5000–7000 g·mol−1 range and differing in the length of the polylactide blocks were prepared. The protecting isopropylidene group was removed in trifluoracetic acid to generate amphiphilic triblock copolyesters bearing free hydroxyl groups in the central block. All copolyesters started to decompose approximately at 260–280 °C, were semicrystalline, and readily degraded by hydrolysis of the main chain under both acid and basic conditions. The acetalized copolyesters had a single Tg, whereas free-hydroxyl bearing copolyesters showed two Tg indicative of blocks phase separation. All copolyesters were able to form nanoparticles with average diameters within the ~200–450 nm range. The influence of the block lengths and protection/deprotection of the hydroxyl groups on size and ζ-potential of the nanoparticles was evaluated.

Fully biobased triblock copolyesters from l-lactide and sulfur-containing castor oil derivatives: Preparation, oxidation and characterization

The synthesis and characterization of fully biobased ABA triblock copolyesters from PLA and castor oil derivatives are described. The synthetic strategy uses a dihydroxy telechelic polyester as a macroinitiator for the ring opening polymerization of l-lactide. This macroinitiator was obtained from a sulfur-containing hydroxyacid derivative of 10-undecenoic acid, which undergoes self-polycondensation with low amounts of biobased 1,4-butanediol, enables the obtention of two prepolymers of different weight. Two series of triblock copolyesters with different percentage of PLA contents were prepared and the resulting thioether-bearing copolyester oxidized to polysulfones. Both series of copolyesters showed improved thermal stability, decrease of crystallinity and a similar hydrophilicity with respect to the PLA homopolymer.

Robot Assisted Synthesis and Characterization of Polyester-based Polyurethanes

ABSTRACTDihydroxy telechelics are precursors for the synthesis of multiblock copolymers. In order to synthesize high molecular weight polymers with good elastic properties it is necessary to gain detailed knowledge of the reaction behavior of these precursors. Therefore it was explored whether the polyaddition reaction of polyester-diols can be established in a robotic synthesizer platform to facilitate the elucidation of reaction characteristics. A series of 16 reactions was performed using a telechelic polyester and trimethylhexamethylene diisocyanate. The chain extension behavior of the building block was compared with respect to the Carothers equation. It was found, that the chain extension behavior follows the expected trend. The molecular weight of the polymers increased when the optimal ratio of reactive groups was approached.

α,ω-Di(glycerol carbonate) telechelic polyesters and polyolefins as precursors to polyhydroxyurethanes: an isocyanate-free approach

α,ω-Di(glycerol carbonate) telechelic poly(propylene glycol) (PPG), poly(ethylene glycol) (PEG), poly(ester ether) (PEE), and poly(butadiene) (PBD) have been synthesized through chemical modification of the corresponding α,ω-dihydroxy telechelic polymers (PPG-OH2, PEG-OH2, PEE-OH2 and PBD-OH2, respectively). Tosylation of the polymer diols with 4-tosylmethyl-1,3-dioxolan-2-one (GC-OTs) afforded, in high yields, the desired PPG, PEG, PEE and PBD end-capped at both termini with a five-membered ring cyclic glycerol carbonate (4-hydroxymethyl-1,3-dioxolan-2-one, GC). The GC-functionalization of the polymers at both chain-ends has been confirmed by NMR (1H, 13C, 1D and 2D) and FTIR spectroscopies. Using PPG-GC2 to demonstrate the concept, the corresponding polyhydroxyurethanes (PHUs/non-isocyanate polyurethanes (NIPUs)) have been subsequently prepared following a non-isocyanate method upon ring-opening catalyst-free polyaddition of the PPG-GC2 with JEFFAMINEs (Mn = 230–2000 g mol−1). The effect of various additives introduced during the polyaddition reaction has been studied at different temperatures. In particular, addition of LiBr (5 mol%) to the reaction medium was found to slightly promote the cyclocarbonate/amine reaction. The polymerization process was supported by FTIR and SEC analyses.

Vegetable oils as platform chemicals for polymer synthesis

AbstractNatural vegetable oils have been transformed in polymers following three main routes. The first is the direct polymerization through the double bonds of the fatty acid chain. The cationic copolymerization of soybean oil with styrene, divinylbenzene, and different amounts of styrenic monomers containing Si allows producing materials with improved mechanical and flame retardant properties. The second route is the functionalization of the triglyceride double bonds to introduce readily polymerizable groups: The singlet oxygen photoperoxidation–dehydration of the allylic positions of the high oleic sunflower oil allows producing enone‐containing triglycerides that are chemically crosslinked with aromatic diamines through aza‐Michael reactions. At high temperatures, this curing reaction proceeds through a complex mechanism leading to quinoline moieties. This new crosslinking approach can be also applied to aldehyde containing triglycerides. The third route consists of using plant oil‐derived chemicals like 10‐undecenoic acid to produce tailor made monomers. Acyclic diene metathesis polymerization has been applied to allyl 10‐undecenoate, 10‐[2′,5′‐bis(10‐undecenoyloxy)phenyl]‐9,10‐dihydro‐9‐oxa‐10‐phospha‐phenanthrene‐10‐oxide, and 1,3‐bis(10‐undecenoyl)glycerol to prepare a set of polyesters with different phosphorus and hydroxyl contents. Moreover thiol‐ene “click” coupling of allyl 10‐undecenoate with mercaptoethanol, 3‐mercaptopropanoic acid, and 3‐mercaptopropyl‐trimethoxysilane has been used to produce difunctional telechelic polyesters.

Effect of ethylene glycol on the end group structure of poly(3-hydroxybutyrate)

Ralstonia eutropha was cultivated in a culture medium supplemented with ethylene glycol (EG), which is known to act as a chain transfer agent in the production of poly(3-hydroxybutyrate) (PHB). The PHB extracted from the bacterial cells was analyzed by 1H and 31P NMR spectroscopies and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The addition of EG exerted a remarkable influence on the mass of production and molecular weight of PHB, and then was found to result in chain transfer and termination reactions. MALDI-TOF MS of the partially hydrolyzed PHB revealed that either succinate or glutarate combined with the hydroxyl terminals of PHB as polymerization starters. From 31P NMR analysis, the carboxyl groups of the succinyls and glutaryls held in the terminals of the isolated PHB were found to be capped with EG, giving the telechelic polyester with hydroxy functionalities. Based on these results, we propose a plausible mechanism of enzymatic polymerization in the microbial PHB synthesis in the presence of EG.

Synthesis and characterization of telechelic phosphine oxide polyesters and cobalt(II) chloride complexes

A monofunctional phosphine oxide containing endcapping reagent, 4-carboxyphenyl biphenyl phosphine oxide, was synthesized for the preparation of telechelic polyester oligomers. The chemical structure of the endcapping reagent was verified using NMR spectroscopy, mass spectroscopy, and elemental analysis. Phosphine oxide telechelic polyesters were prepared for the first time via copolymerization of a low molar mass polyester oligomer precursor and the phosphine oxide endcapping reagent in the melt state. The quantitative incorporation of telechelic phosphine oxide functionality was confirmed using 1H NMR spectroscopy and elemental analysis. The corresponding complexes of phosphine oxide terminated polyesters and cobalt(II) chloride were prepared via charging the cobalt salt at the onset of melt polymerization. 31P { 1H} NMR spectroscopy, FT-IR spectroscopy, and UV–vis spectroscopy indicated that the cobalt(II) ion preferentially coordinated with the phosphine oxide end groups. The complexes exhibited higher melt viscosity than their salt-free analogues due to the formation of coordinated polymers. The presence of the telechelic phosphine oxide end groups also aided in the homogeneous dispersion of the cobalt salt in a poly(ethylene terephthalate) (PET) matrix.

Synthesis of trimethoxy- or triethoxysilane-endcapped polylactones via a bismuth(III)hexanoate-catalyzed one-pot-procedure

It was shown that bismuth(III)hexanoate (Bi(OHex)3) efficiently and selectively catalyzes the addition of tetra(ethylene glycol) (TEG) onto the isocyanate group of 3-isocyanatopropyl triethoxysilane, IPTES. δ-Valerolactone (δ VL), ε-caprolactone (εCL) and D,L-lactide were polymerized by initiation with TEG/Bi(OHex)3. The resulting telechelic polyesters were in situ functionalized with IPTES or with 3-isocyanatopropyl trimethoxysilane, IPTMS. Using pentaerythritol as co-initiator of Bi(OHex)3 and εCL as monomer, star-shaped polylactones having triethylsilyl end-groups were synthesized in a one-pot-procedure. All functionalized polyesters were characterized by 1H-NMR and 13C-NMR spectroscopy and by MALDI-TOF mass spectrometry. Bi(OHex)3 is a remarkable initiator and catalyst, because of its extraordinary low toxicity.

Telechelic polylactones functionalized with trimethoxysilyl groups

Telechelic poly(ε-caprolactone)s or poly( d, l-lactide)s were prepared by SnOct 2-initiated polymerization of ε-caprolactone (εCL) or d, l-lactide ( d, l-LA) coinitiated with 1,4-butane diol or tetra(ethylene glycol). These telechelic polyesters were in situ functionalized with 3-isocyanatopropyl trimethoxysilane (IPTMS) by SnOct 2-catalized addition of the OH-endgroups. Analogously, star-shaped polyesters were synthesized and functionalized using 1,1,1-trishydroxymethyl propane or pentaerythritol as coinitiators. All functionalized polymers were characterized by 1H NMR and MALDI-TOF mass spectra. In crosslinking experiments with oligo(ethylene–glycol)s the trimethoxysilyl groups proved to be 10–30-fold more reactive than triethoxysilyl end-capped polyesters.

Telechelic polyesters of ethane diol and adipic or sebacic acid by means of bismuth carboxylates as non-toxic catalysts

Dimethyladipate or dimethylsebacate were polycondensed with an excess of 1,2-ethane diol in bulk using two different temperature/time programs. Bismuth(III) n-hexanoate (BiHex 3), tin(II)2-ethylhexanoate (SnOct 2) and titanium tetrabutoxide were used as catalysts. Only the bismuth catalyst yielded clean telechelic polyesters having two ethylene glycol endgroups. With SnOct 2 cyclic oligoesters were obtained as byproducts. Ti(OBu) 4 yielded OH-terminated linear chains containing large amounts of diethylene glycol units (detectable up to three ether groups per chain). Furthermore, small amounts of cycles were also formed. Acid-catalyzed polycondensations of ethylene glycol with sebacic acid gave low yields of low oligomers, part of which contained diethylene glycol units.

Polylactones, 68

AbstractFull Paper: Using Sn(II)2‐ethylhexanoate (SnOct2) in combination with 1,4‐butanediol, 1,1,1‐tris(hydroxymethyl)propane (THMP) or pentaerythritol as initiator systems telechelic polyesters or star‐shaped homopolyesters of ε‐caprolactone (ε‐CL) or L,L‐lactide (L‐LA) were prepared. These homopolymers were characterized by solution viscosities, 1H NMR and MALDI‐TOF mass spectra. Using preformed homopolymers as coinitiators star‐shaped polymers having two‐block star arms were obtained. Polymerizations of equimolar mixtures of two monomers yielded star‐shaped polymers with random copolyesters as star arms. The blockiness or randomness of the star arms was characterized by 13C NMR spectroscopy. Homo‐ and copolymerizations of trimethylene carbonate (TMC) were also studied, but they were plagued by intensive side reactions such as formation of cyclic oligomers, coinitiation with water and crosslinking via transesterification.Star‐shaped polymers having two‐block star arms obtained in this study.magnified imageStar‐shaped polymers having two‐block star arms obtained in this study.

Solid-supported well-defined synthesis of telechelic polyester by acid-promoted ring-opening polymerization of ?-caprolactone

Solid-supported well-defined synthesis of telechelic polyester by acid-promoted ring-opening polymerization of ?-caprolactone

In vitro biosynthesis of polyesters with isolated enzymes in aqueous systems and organic solvents

In vitro synthesis of aliphatic polyesters was achieved by lipase-catalysed polymerization. A lipase-catalysed polycondensation of a dicar☐ylic acid and a glycol proceeded in an aqueous medium in which a dehydration took place in water. From a combination of sebacic acid and 1,8-octanediol, the corresponding polyester with a molecular weight of 1600 was obtained. Lipase also catalysed a ring-opening polymerization of lactones with different ring sizes. The polymerization behaviors depended on the lipase origin and the monomer structure. Macrolides (12-, 13- and 16-membered) showing much lower anionic polymerizability were enzymatically polymerized faster than ɛ-caprolactone. The lipase-catalysed polymerizability of these lactones was evaluated by Michaelis-Menten kinetics. The enzymatic ring-opening polymerization of lactones was expanded to an enantioselective polymerization of 3-methyl-4-oxa-6-hexanolide. The polymerization of the ( S)-isomer proceeded much faster than that of the ( R)-isomer. Single-step synthesis of end-functional polymers, methacryl-type macromonomer and a telechelic polyester having a car☐ylic acid group at both ends, was achieved by the polymerization in the presence of vinyl methacrylate and divinyl sebacate, respectively. Lipase catalysis provided the copolymerization of lactones, dicar☐ylic acid divinyl esters and glycols, in which two different types of polymerization—ring-opening polymerization and polycondensation—simultaneously occurred via the same acyl-lipase intermediate.

Macromolecular engineering of polylactones and polylactides: 13. Synthesis of telechelic polyesters by coupling reactions

Abstract Aromatic diisocyanates, such as phenylene-1,4-diisocyanate have proved to be very effective coupling agents of α-X functional ω-hydroxy poly-e-caprolactone (PCL). Very high yields (> 98%) have been observed in the presence of triethylamine, in tetrahydrofuran. Accordingly α,ω-X functional PCL of a two-fold molecular weight have been obtained and characterized by size exclusion chromatography and nuclear magnetic resonance spectroscopy. More interestingly, the same coupling reactions have been successfully carried out when applied to the precursor living polyester (XCH2OPCLOAlEt2) rather than to the chains recovered after hydrolysis of the living propagating sites. Terephthalic acid chloride has been the most efficient coupling agent and, in the presence of pyridine, has yielded quantitatively the expected α,ω-functional polyesters.