Abstract: Polyester-based polymers represent excellent candidates in synthetic biodegradable and bioabsorbable materials for medical applications owing to their tailorable properties. The use of synthetic polyesters as biomaterials offers a unique control of morphology, mechanical properties and degradation profile through monomer selection, polymer composition (i.e. copolymer vs. homopolymer, stereocomplexation etc.) and molecular weight. Within this review, the synthetic routes, degradation modes and application of aliphatic polyester- and polycarbonate-based biomaterials are discussed.

Abstract: Lignin polymerization has been considered as an effective approach for lignin valorization Herein we report the synthesis of a series of new lignin-based copolymers (lignin–poly(e-caprolactone-co-lactide), lignin–PCLLA) via solvent-free ring-opening polymerization Lignin–PCLLA copolymers with tunable molecular weights (10 to 16 kDa) and glass transition temperatures (−40 to 40 °C) were obtained Such copolymers were engineered into ultrafine nanofibers by blending with polyesters (polycaprolactone, PCL and poly(l-lactic acid), PLLA) via electrospinning Both PCL/lignin–PCLLA and PLLA/lignin–PCLLA nanofibers displayed uniform and beadless nanofibrous morphology The size (diameters ranging from 300 to 500 nm) and tensile tests of the obtained nanofibers indicated that the lignin copolymers are miscible with the polyester matrices and can significantly improve the mechanical properties of the nanofibers Moreover, good antioxidant activity and biocompatibility of the lignin nanofibers were demonstrated in

Abstract: Polyurethanes (PU) are widely used synthetic polymers. The growing amount of PU used industrially has resulted in a worldwide increase of plastic wastes. The related environmental pollution as well as the limited availability of the raw materials based on petrochemicals requires novel solutions for their efficient degradation and recycling. The degradation of the polyester PU Impranil DLN by the polyester hydrolases LC cutinase (LCC), TfCut2, Tcur1278 and Tcur0390 was analyzed using a turbidimetric assay. The highest hydrolysis rates were obtained with TfCut2 and Tcur0390. TfCut2 also showed a significantly higher substrate affinity for Impranil DLN than the other three enzymes, indicated by a higher adsorption constant K. Significant weight losses of the solid thermoplastic polyester PU (TPU) Elastollan B85A-10 and C85A-10 were detected as a result of the enzymatic degradation by all four polyester hydrolases. Within a reaction time of 200 h at 70 °C, LCC caused weight losses of up to 4.9% and 4.1% of Elastollan B85A-10 and C85A-10, respectively. Gel permeation chromatography confirmed a preferential degradation of the larger polymer chains. Scanning electron microscopy revealed cracks at the surface of the TPU cubes as a result of enzymatic surface erosion. Analysis by Fourier transform infrared spectroscopy indicated that the observed weight losses were a result of the cleavage of ester bonds of the polyester TPU.

Abstract: Polypeptides. Polysaccharides. Bacterial Polyesters and Their Models Obtained by Ring-Opening Polymerization of b-Lactones. Synthetic Polyphosphates Related to Nucleic and Teichoic Acids.

Abstract: Biodegradable polyesters have a large potential to replace persistent polymers in numerous applications and to thereby reduce the accumulation of plastics in the environment Ester hydrolysis by extracellular carboxylesterases is considered the rate-limiting step in polyester biodegradation In this work, we systematically investigated the effects of polyester and carboxylesterase structure on the hydrolysis of nanometer-thin polyester films using a quartz-crystal microbalance with dissipation monitoring Hydrolyzability increased with increasing polyester-chain flexibility as evidenced from differences in the hydrolysis rates and extents of aliphatic polyesters varying in the length of their dicarboxylic acid unit and of poly(butylene adipate-co-terephthalate) (PBAT) polyesters varying in their terephthalate-to-adipate ratio by Rhizopus oryzae lipase and Fusarium solani cutinase Nanoscale nonuniformities in the PBAT films affected enzymatic hydrolysis and were likely caused by domains with elevated tere

Abstract: Biodegradable synthetic polymers have been widely used as tissue engineering scaffold materials. Even though they have shown excellent biocompatibility, they have failed to resemble the low stiffness and high elasticity of soft tissues because of the presence of massive rigid ester bonds. Herein, we synthesized a new thermoplastic polyurethane elastomer (CTC-PU(BET)) using a polyester ether triblock copolymer (polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone triblock copolymer, PCTC) as the soft segment, an aliphatic diisocyanate (hexamethylene diisocyanate, HDI) as the hard segment, and a degradable diol (bis(2-hydroxyethyl)terephthalate, BET) as the chain extender. PCTC inhibited the crystallization and reduced the melting temperature of CTC-PU(BET), and BET dramatically enhanced the thermal decomposition and the hydrolytic degradation rate when compared with conventional polyester-based biodegradable TPUs. The CTC-PU(BET) synthesized in this study possessed a low tensile modulus and tensile strength of 2.2 MPa and 1.3 MPa, respectively, and an elongation-at-break of over 700%. Meanwhile, it maintained a recovery rate of 95.3% and a resilience of 90% over ten cycles of loading and unloading. In addition, TPU could be electrospun into both random and aligned fibrous scaffolds consisting of major microfibers and nanobranches. The 3T3 fibroblast cell culture confirmed that these scaffolds outperformed the conventional biodegradable TPU scaffolds in terms of substrate cellular interactions and cell proliferation. Considering the advantages of these TPU scaffolds, such as the ease of synthesis, low cost, low stiffness, high elasticity, controllable degradation rate, ease of processability, and excellent biocompatibility, they have great prospects for use as tissue engineering scaffold materials for soft tissue regeneration.

Abstract: Summary Due to the rising global environment protection awareness, recycling strategies that comply with the circular economy principles are needed Polyesters are among the most used materials in the textile industry; therefore, achieving a complete poly(ethylene terephthalate) (PET) hydrolysis in an environmentally friendly way is a current challenge In this work, a chemo-enzymatic treatment was developed to recover the PET building blocks, namely terephthalic acid (TA) and ethylene glycol To monitor the monomer and oligomer content in solid samples, a Fourier-transformed Raman method was successfully developed A shift of the free carboxylic groups (1632 cm−1) of TA into the deprotonated state (1604 and 1398 cm−1) was observed and bands at 1728 and 1398 cm−1 were used to assess purity of TA after the chemo-enzymatic PET hydrolysis The chemical treatment, performed under neutral conditions (T = 250 °C, P = 40 bar), led to conversion of PET into 85% TA and small oligomers The latter were hydrolysed in a second step using the Humicola insolens cutinase (HiC) yielding 97% pure TA, therefore comparable with the commercial synthesis-grade TA (98%)

Abstract: The formation of bio-derived materials is gaining momentum in academic and industrial laboratories, though the use of terpene oxides as renewable monomers for the preparation of bio-based polymers yet remains limited. In order to advance the impact of such monomers, we have investigated the use of terpene-derived epoxides (limonene oxide, carene oxide, limonene dioxide, and menthene oxide) for the ring-opening copolymerization (ROCOP) in the presence of various aromatic anhydrides. These copolymerization reactions were mostly performed under mild reaction conditions (65 °C; low loading of catalyst: 0.50 mol %) using a binary catalyst composed of a Fe(III)-based aminotriphenolate complex and PPNCl (bis(triphenylphosphine)iminium chloride) providing partially bio-based semiaromatic polyesters with molecular weights of up to 25 kg/mol (Đ = 1.54) and glass transitions spanning a wide range from 59 to 243 °C. The copolymerization reactions proceed with excellent selectivity toward fully alternating polyesters ...

Abstract: Aliphatic polyesters are important biodegradable polymers with wide applications. Polyesters prepared by ring-opening polymerization often have a limited range of properties, because of the minimal functional diversity of available lactone monomers. In this review, synthetic strategies in preparing functional lactone monomers are highlighted, as well as recent controlled polymerization strategies to synthesize functional aliphatic polyesters, which include proton-transfer polymerization, ring opening polymerization of O-carboxyanhydrides, radical ring-opening polymerization of cyclic ketene acetals, and copolymerization of epoxide/anhydride.

Abstract: For the first time, the free-radical copolymerization of cyclic ketene acetals (CKAs) and vinyl ethers (VEs) was investigated as an efficient, yet simple approach for the preparation of functional aliphatic polyesters. The copolymerization of CKA and VE was first predicted to be quasi-ideal by DFT calculations. The theoretical prediction was experimentally confirmed by the copolymerization of 2-methylene-1,3-dioxepane (MDO) and butyl vinyl ether (BVE), leading to rMDO = 0.73 and rBVE = 1.61. We then illustrated the versatility of this approach by preparing different functional polyesters: (i) copolymers functionalized by fluorescent probes; (ii) amphiphilic copolymers grafted with poly(ethylene glycol) (PEG) side chains able to self-assemble into PEGylated nanoparticles; (iii) antibacterial films active against Gram+ and Gram- bacteria (including a multiresistant strain) and (iv) cross-linked bioelastomers with suitable properties for tissue engineering applications.

Abstract: Hypophosphorous acid-modified chitosan (PCS), as a novel phosphorus-containing chitosan derivative, was first successfully synthesized and characterized by Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy. Subsequently, thin films of the ecofriendly PCS and branched polyethylenimine were deposited on polyester–cotton (PTCO) blends by the layer-by-layer assembly technique, in an effort to enhance their thermal properties and fire resistance properties. Thermogravimetric analysis, thermogravimetric analysis–Fourier transform infrared spectrometry, scanning electron microscopy, and horizontal flame test (HFT) were used to investigate the quality of the coatings as well as their fire resistance performance. The thermal and thermal oxidation stabilities at high temperature were enhanced for all coated PTCO blends. During the HFT, the afterglow phenomenon was eliminated for all coated blends, and self-extinguishing was achieved for the PCS2-20BL sample. It was found that the enhancem...

Abstract: Linear aliphatic polyesters are degradable thermoplastic polymers, which can be obtained by ring-opening polymerization (ROP) of cyclic esters through a coordination-insertion mechanism. Aluminum b ...

Abstract: A range of fully biobased unsaturated polyesters (bio-UPs) derived from 2,5-furandicarboxylic (FDCA), itaconic acid (IA), succinic acid (SA), and 1,3-propanediol (PD) were obtained via direct polycondensation. The chemical structures of the bio-UPs were identified by Fourier transfrom infrared spectroscopy and 1H NMR before they were cured together with a biobased, nonvolatile reactive diluent, guaiacol methacrylate (GM). The thermal and mechanical characterizations of the cured bio-UPs were evaluated using thermogravimetric analysis, 3-point bending tests, and dynamic mechanical analysis. Results showed that the thermal properties, flexural strength, and modulus of the cured bio-UPs were greatly improved after the introduction of FDCA. The temperature of 5% thermal weight loss reached 330 °C, and the flexural strength and modulus reached 122.8 and 3521 MPa, respectively. These results indicate that the bio-UPs have the potential to replace petroleum-based UPs.

Abstract: High molecular weight aliphatic polyesters were synthesized from biobased 1,5-pentanediol and aliphatic diacids with 4, 5, 6, 9, 10, or 12 carbon atoms via melt polycondensation. The poly(1,5-pentylene dicarboxylate)s were characterized with intrinsic viscosity, gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), and tensile testing. The effects of dicarboxylate chain length on crystalline structure and thermo-mechanical properties were investigated. All the polyesters had weight-average molecular weight over 100,000 g/mol or intrinsic viscosity over 1.05 dL/g except poly(1,5-pentylene adipate) (PPeA), which was less thermally stable than others. As semicrystalline polymers, they have a polyethylene-like crystal structure and crystallize rapidly except poly(1,5-pentylene succinate) (PPeS). As a whole, the crystallizability and melting temperature (Tm) increase with dicarboxyla...

Abstract: Aliphatic biodegradable polyesters have been the most widely used synthetic polymers for developing biodegradable devices as alternatives for the currently used permanent medical devices. The performances during biodegradation process play crucial roles for final realization of their functions. Because physiological and biochemical environment in vivo significantly affects biodegradation process, large numbers of studies on effects of mechanical loads on the degradation of aliphatic biodegradable polyesters have been launched during last decades. In this review article, we discussed the mechanism of biodegradation and several different mechanical loads that have been reported to affect the biodegradation process. Other physiological and biochemical factors related to mechanical loads were also discussed. The mechanical load could change the conformational strain energy and morphology to weaken the stability of the polymer. Besides, the load and pattern could accelerate the loss of intrinsic mechanical properties of polymers. This indicated that investigations into effects of mechanical loads on the degradation should be indispensable. More combination condition of mechanical loads and multiple factors should be considered in order to keep the degradation rate controllable and evaluate the degradation process in vivo accurately. Only then can the degradable devise achieve the desired effects and further expand the special applications of aliphatic biodegradable polyesters.

Abstract: Unsaturated polyester resin (UPe)-based nanocomposites and fumed silica Aerosil R812S, R805 and R816, and R200 modified with phenyl terminal group, R200NPh, were prepared. UPe resins were synthesized from maleic anhydride and products of glycolysis, obtained by polyethylene terephthalate depolymerization with dipropylene glycol in the presence of tetrabutyl titanate catalyst. The obtained unsaturated polyesters were characterized by acid, hydroxyl, and iodine values and by FTIR and NMR analysis. The microstructural analysis of the prepared nanocomposites, performed by using transmission electron microscopy, confirmed that silica nanoparticles formed chain-like aggregates in the polymer matrix. The presence of modified silica nanoparticles had no influence on the glass transition temperature and thermal stability of polyester matrix. The tensile modulus, stress at break, and hardness of cured products increased with increasing silica content. The impact strength of cured samples was not influenced by the silica content. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Abstract: A family of monomers, including 2,5-hexandiol, 2,7-octandiol, 2,5-furandicarboxylic acid (FDCA), terephthalic acid (TA), and branched-chain adipic and pimelic acid derivatives, all find a common derivation in the biomass-derived platform molecule 5-(chloromethyl)furfural (CMF). The diol monomers, previously little known to polymer chemistry, have been combined with FDCA and TA derivatives to produce a range of novel polyesters. It is shown that the use of secondary diols leads to polymers with higher glass transition temperatures (Tg) than those prepared from their primary diol equivalents. Two methods of polymerisation were investigated, the first employing activation of the aromatic diacids via the corresponding diacid chlorides and the second using a transesterification procedure. Longer chain diols were found to be more reactive than the shorter chain alternatives, generally giving rise to higher molecular weight polymers, an effect shown to be most pronounced when using the transesterification route. Finally, novel diesters with high degrees of branching in their hydrocarbon chains are introduced as potential monomers for possible low surface energy materials applications.

Abstract: An azobenzene-containing thermotropic liquid crystalline polyester showing unique thermo- and photo-responsive behaviours was synthesized by polycondensation from mesogenic dial 4,4′-bis(6-hydroxyhexyloxy)azobenzene (BHHAB) with 2-phenylsuccinic acid (PSA), and named as poly(4,4′-bis(6-hydroxyhexyloxy)azobenzene phenylsuccinate) (PBHPS). Liquid crystalline behaviours were investigated through differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). PBHPS showed a smectic phase with strong π–π interactions between the adjacent phenyl rings or between the side group and mesogenic unit, which could be regarded as physical crosslinking points that made PBHPS have good shape memory and self-healing properties. A series of PBHPS/methylcellulose bilayer films were prepared to study the reversible photo-mechanical properties. UV-vis absorption spectra were used to study the reversible photo-responsive behaviour of the polyester, proving that the reversible photoisomerization-induced volume expansion of the PBHPS layer resulted in good reversible photo-responsive properties.

Abstract: A series of renewable unsaturated polyesters were synthesized from itaconic acid (IA), succinic acid, and 1,4-butanediol by solvent-free polycondensation. Previous studies utilizing IA to make polyesters for coating applications have shown great potential; however, the curing and material properties have not been investigated in detail. The aim of this study was to investigate how the curing is affected by the amount of unsaturations and how well itaconate-based polyesters crosslink without the addition of any other unsaturated monomers or reactive diluents. The chemical structures of the polyesters were confirmed with FTIR, 1H-NMR, and THF–SEC. The degree of curing was studied with FTIR, and the mechanical properties of the crosslinked polyesters were evaluated with DMA, pendulum hardness, and microindentation. The degree of curing was found to be up to 75%, and furthermore, it was found that the final mechanical properties of the crosslinked coatings could be tuned by modifying the IA content in the monomer composition. The results from DMA showed that there is a clear trend between mechanical properties and crosslinking density.