Synthesis and hydrolytic degradation of poly(ethylene succinate) and poly(ethylene terephthalate) copolymers

The conditions of synthesis of statistical poly(ethylene succinate-co-terephthalate) copolymers (2GTS) and high molecular weight poly(ethylene succinate) (PES) with good hydrolytic and optical parameters, designed for the production of biodegradable products and resins, are presented in this article. Copolymers were prepared by melt polycondensation of bis-(β-hydroxyethylene terephthalate) (BHET) and succinic acid (SA) with excess of ethylene glycol (2G) in the presence of a novel titanium/silicate catalyst (C-94) and catalytic grade of germanium dioxide (GeO₂) as cocatalyst. The chemical structure and physical properties of those materials were characterized by ¹H NMR, FT-IR, dynamical-mechanical thermal analyses (DMTA), differential scanning calorimetry (DSC), solution viscosity and spectroscopic methods. The hydrolytic degradation was performed in a water solution with variable pH, also in garden soil and in compost. The highest hydrolytic degradation rate was observed for pH 4 and for compost. Better hydrolytic degradation values in compost medium were observed for copolyester prepared in the presence of GeO₂ as polycondensation cocatalyst. The copolyester with 40 mol% of aliphatic units was chosen for industrial syntheses which were performed in ELANA and subsequently the processing parameters and compatibility with potato starch of this polyester were checked by BIOP Biopolymer Technologies AG.     

聚氧乙烯功能基复合修饰聚氨酯的合成及其血液相容性研究 (Ⅰ)──聚氨酯-接枝-十八烷基聚氧乙烯

通过十八烷基聚氧乙烯和环氧氯丙烷的封端反应制备了α-环氧基-ω-十八烷基聚氧乙烯大单体.并采用BF₃·Et₂O引发THF和大单体共聚合,得到了梳状的十八烷基聚氧乙烯接枝共聚醚.以该共聚醚为软段合成了十八烷基和聚氧乙烯复合修饰的聚氨酯(PEU-g-PEO-C₁₈).通过血小板粘附试验对材料的体外抗凝血性实验结果表明,采用具有选择性吸附白蛋白功能的十八烷基和PEO复合修饰聚氨酯,材料表面血小板粘附量明显减少.材料血液相容性的改善可能来源于疏水性的十八烷基和亲水性聚氧乙烯的协同作用.     

Degradable Polymers. III. Synthesis and Characterization of Aliphatic Thermoplastic Block Copolyesters

A group of new block copolymers has been synthesized and characterized. The copolyesters were step-polymerized with six different poly-ether feeds, ranging from 21.1 to 53.3 mol%. The resulting polyethylene succinate)-b-poly(tetramethylene glycol) (PES/PTMG) polymers were characterized by GPC, DSC, IR, and NMR, and tensile strength measurements were performed. The molar composition of the polymers was determined by NMR and also correlated with IR. The compositions of the polymers agree well with those expected from the composition of the feed. Fibers for tensile strength measurements were extruded, and samples for dynamic mechanical tests (DMTA) were compression molded. The crystallinity, the melting temperature, the fiber strength, and the elastic bending modulus decreased with increasing polyether content, whereas the breaking strain increased.     

Preparation, characterization and hydrolytic degradation of poly[p-dioxanone-(butylene succinate)] multiblockcopolymer

A series of poly[p-dioxanone-(butylene succinate)] (PPDOBS) copolymers were prepared from p-dioxanone (PDO), 1,4-butanediol and succinate acids through a two-step process including the initial prepolymer preparation of poly(p-dioxanone)diol (PPDO-OH) and poly(butylene succinate)diol (PBS-OH) and the following copolymerization of the two kinds of prepolymers by coupling with hexamethylene diisocyanate (HDI). The molecular structures of the prepared PPDO-OH, PBS-OH and PPDOBS were characterized by hydrogen nuclear magnetic resonance spectroscopy (¹H NMR). The crystallization of the copolymers was investigated by using differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide angle X-ray diffraction (WAXD). It has been shown that the crystallization rate and the degree of crystallization increases with the increase of the weight fraction of poly(butylene succinate) (PBS) blocks in the copolymers. In phosphate buffer solution with pH 7.4 at 37 °C for 18 weeks, the hydrolytic degradation behaviors of the copolymers were studied. The changes of retention weight, water absorption, pH value, and surface morphologies with the degradation time showed that the hydrolytic degradation rate of PPDOBS could be controlled by adjusting the weight fraction of poly(p-dioxanone) (PPDO) and PBS blocks in the copolymers. The changes of the thermal properties of PPDOBS during the degradation were also investigated by DSC.     

易水解聚酯的合成及其水解性能

作者合成了一种可纺性易水解聚酯,由于其可与其他熔纺高聚物进行复合或共混纺丝,制成海岛型纤维,这种海岛型纤维只要经过热（碱）水处理,就能形成微细纤维,使该聚合物有着非常广泛的应用前景［１］．本文主要讨论这种可成纤易水解聚酯的合成及其水解性能．１原料对苯...     

AB型两亲聚L-谷氨酸-苄酯-聚乙二醇嵌段共聚物的合成与表征

利用L 谷氨酸和苯甲醇反应制备了L 谷氨酸 苄酯 ,然后将其与三聚光气反应制备了N 羧基 L 谷氨酸 环内酸酐 (NCA) .以聚乙二醇单甲醚 (MPEG)为原料 ,制备了端氨基聚乙二醇单甲醚 (MPEG NH2 ) ,并以此作为引发剂 ,引发NCA开环聚合 ,合成了不同分子量的聚L 谷氨酸 苄酯 聚乙二醇单甲醚 (PBGM )嵌段共聚物 .利用IR、1 H NMR、DSC、GPC等方法对共聚物结构进行了表征 .结果表明 ,MPEG NH2 引发NCA开环聚合得到的是嵌段共聚物 ,通过1 H NMR谱得到共聚物组成及数均分子量 ;随着共聚物中MPEG含量的增高 ,聚L 谷氨酸 苄酯的亲水性有所改善     

配位有机硅在聚醚氨酯中的应用

研究了直接从无定型二氧化硅出发,与乙二醇、氢氧化钾反应,生成高反应活性的五配位硅钾络合物,并以此为原料与2－氯乙醇反应制备双羟基四配位有机硅单体,该单体作为扩连剂再与异氰酸酯基封端的聚醚或聚酯进行低温溶液缩聚反应合成含硅聚醚氨酯,经红外光谱,热重分析,胶渗透色法测定分子量等对合成的物质作了结构表征,热重分析表明该聚合物的耐热性能有所提高,胶渗透色谱法测定分子量高于10万。     

Polymerization of adsorbed monolayers. III. Preliminary structure studies in dilute solution of the insertion polymers

Insertion poly(methyl acrylate) and poly(methyl methacrylate) were prepared from monomers adsorbed in monolayers on the surface of montmorillonite clay, both in the presence and in the absence of bifunctional crosslinkers (ethylene glycol dimethacrylate and tetramethylene glycol dimethacrylate). The insertion poly(methyl acrylate) and the crosslinked insertion poly(methyl methacrylate) and dilute-solution properties quite different from conventional polymers of these monomers, the differences including high light-scattering molecular weights combined with low viscosities, low values of the second virial coefficient, unusually large variations of the Huggins' constant k′ with the time-temperature history of the solutions, and low sedimentation velocities. These properties suggest that the insertion polymers have compact structures and are consistent with the postulate of sheetlike macromolecules. The dilute-solution properties of insertion poly(methyl methacrylate) made without crosslinker, unlike those of similarly prepared poly(methyl acrylate), were similar to those of conventional poly(methyl methacrylate). This difference in behavior is attributed to the different tendencies of the two monomers to undergo branching or crosslinking during radical polymerization.     

Synthesis and characterization of novel degradable photocrosslinked poly(ether‐anhydride) networks

New degradable poly(ether‐anhydride) networks were synthesized by UV photopolymerization. Dicarboxylated poly(ethylene glycol) (PEG) or poly(tetramethylene glycol) (PTMG) was reacted with an excess of methacrylic anhydride to form dimethacrylated macromers containing anhydride linkages. The percent of conversion for the macromer formation was more than 80% at 60 °C after 24 h. ¹H NMR and IR spectroscopies show the presence of anhydride linkages in the macromer. In vitro degradation studies were carried out at 37 °C in PBS with crosslinked polymer networks formed by UV irradiation. All PEG‐based polymers degraded within 2 days, while PTMG‐based polymers degraded by 50% of the initial weight after 14 days. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1277–1282, 2000     

Effects of polymerization conditions on the in vitro hydrolytic degradation of plaques of poly(dl-lactic acid-block-ethylene glycol) diblock copolymers

In the case of poly(lactic acid) stereocopolymers, it has been shown that the hydrolytic degradation of derived devices depends very much on whether zinc lactate or tin octoate was used to polymerize lactides. In contrast, no effect was found in the case of nanoparticles derived from poly(dl-lactic acid)-block-poly(ethylene glycol) copolymers obtained by anionic polymerization of dl-lactide initiated by the sodium salt of monomethoxypoly(ethylene glycol) or by coordination-insertion polymerization of dl-lactide initiated by monomethoxypoly(ethylene glycol) in the presence of tin octoate as catalyst. To understand the difference of behaviour, in vitro hydrolytic degradation of thick plates made of the same copolymers but under different conditions was investigated. Changes were monitored by ¹H Nuclear Magnetic Resonance, Size Exclusion Chromatography, Electrospray Mass Spectrometry and Capillary Zone Electrophoresis. It is shown that chain cleavage occurred from the very beginning of degradation and that plates disintegrated after 13 weeks. In all cases, degradation proceeded faster inside than at the surface, in contrast to what was observed for nanoparticles. Tin-type copolymer plates degraded more slowly than sodium macroalcoholate-type ones and were sensitive to purification conditions, in contrast to the latter.     

Radiation effects on a linear model compound for polyethers

Radiation effects on a model polyether - poly(tetramethylene) glycol (PTMG) induced by high energy radiation were investigated. To understand the degradation mechanism, electron paramagnetic resonance (EPR), Fourier transform infra-red spectroscopy (FTIR), electrospray and gas mass spectrometry (ESI-MS and gas-MS), were carried out to identify radicals and chemical modifications. Size exclusion chromatography (SEC) was used to follow the evolution of the distribution of molecular weight. On the basis of the results, a mechanism of degradation for PTMG is proposed.     

Synthesis and characterization of hydrophilic thermotropic block copolyetheresters

The block copolyetheresters with a hard segment of poly (hexamethylene p,p′-bibenzoate) and a soft segment of poly (ethylene oxide) were prepared by melt polycondensation of dimethyl-p,p′-bibenzoate, 1,6-hexanediol, and polyethylene glycol (PEG) with molecular weights of 400, 1000, 2000, or 4000. These block copolyetheresters were characterized by intrinsic viscosity, GPC, FT-IR, ¹H-NMR, and water absorption. The thermotropic liquid crystalline properties were investigated by DSC, polarized microscope, and x-ray diffraction. The block copolyetheresters exhibit smectic liquid crystallinity due to the polyester segment. The transitions are dependent on the molar content and the molecular weight of PEG used. The block copolyetheresters show high water absorption due to the hydrophilic nature of the poly (ethylene oxide) segment. The water absorption increases with increasing PEG content. As the molecular weight of PEG increases, the water absorption increases significantly. The results indicate that the water absorption of the poly (ethylene oxide) segment in the block copolymers is affected by the presence of polyester segments. © 1995 John Wiley & Sons, Inc.     

Application of New Modified Poly(ethylene Oxide)-Block-Poly(propylene oxide)-Block-Poly(ethylene oxide) Copolymers as Demulsifier for Petroleum Crude Oil Emulsion

Water soluble nonionic amphiphilic block copolymers based on hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(propylene glycol) (PPG) were prepared. Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) copolymers, PEG-PPG-PEG, were prepared in the normal condition. The chemical composition and molecular weights of the prepared copolymers were determined from ¹H NMR and GPC techniques. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The prepared nonionic surfactants were evaluated as demulsifiers for water in crude-oil emulsions that were pronounced at different ratios of crude oil: water at 318 K and 333 K. The experimental results showed that the dehydration rate of the prepared demulsifiers reached 100% based on demulsifier chemical compositions and concentrations.     

Characterization of polysuccinate and hydroxyapatite‐based nanocomposites containing poly(ester‐anhydride) microspheres

Repair and regeneration of bone defects with particular shape may be enhanced by in situ forming biomaterials which can be used in minimal invasive surgery. This study is aimed to prepare novel in situ forming biodegradable nanocomposites based on poly(3‐allyloxy‐1,2‐propylene) succinate (PSAGE) and nanosized hydroxyapatite (HA). These nanocomposite materials contain poly(ester‐anhydride) (PEA) microspheres embedded in a polyester matrix prepared by crosslinking PSAGE with oligo(1,2‐propylene maleate) and methacrylic monomers. Methyl methacrylate and one of hydrophilic oligo(ethylene glycol) methacrylates with different functionality and various length of oligooxyethylene chains were used as polymerizable diluents. Incorporation of microspheres which degrade faster than crosslinked polyester matrices enables formation of porous structure in situ. The obtained materials are liquid before curing and harden in several minutes with moderate exothermic effect. The effect of the composition of nanocomposite materials on selected properties, such as water sorption, mechanical strength, porosity and hydrolytic degradation process, was investigated. Rheological behavior and injectability of liquid formulations were studied. Analysis by energy dispersive spectroscopy confirmed the presence of characteristic features of HA in the nanocomposite materials. The morphology of the cured nanocomposites subjected to hydrolytic degradation was evaluated by scanning electron microscopy. The MTS cytotoxicity assay was carried out for extracts from crosslinked materials using hFOB1.19 cells. It was found that the extracts exhibit a dose‐dependent cytotoxic response. Copyright © 2014 John Wiley & Sons, Ltd.     

Degradable Polymers. I. Synthesis,Characterization, and Long-Term in Vitro Degradation of a 14C-Labeled Aliphatic Polyester

Poly(tetramethylene adipate) has been synthesized with and without ¹⁴C labeling at different molecular weights. Degradation tests of the labeled powder inoculated with microorganisms showed a decrease in molecular weight (GPC) and first an increase and later a decrease of crystallinity (DSC). These changes also occurred in the inoculated material, and the results indicate that the degradation process was abiotic hydrolysis which first takes place in the amorphous region. The radioactivity measurements showed that the microorganisms are able to degrade further the oligomers formed during the hydrolysis. The rate of degradation is related to the molecular weight. Unlabeled poly(tetramethylene adipate) was extruded and cold drawn to yield oriented fibers. These fibers retained more than 50% of the original tensile strength during 100 days of abiotic in vitro hydrolysis.     

聚氨酯-接枝-磺化聚氧乙烯的合成及其血液相容性研究

通过梳状的磺化聚氧乙烯接枝共聚醚和４,４’ 二苯甲烷二异氰酸酯（ＭＤＩ）反应,合成了磺酸根离子和聚氧乙烯复合修饰的聚氨酯（ＰＥＵ ｇ ＰＥＯ ＳＯ３Ｎａ）．通过血小板粘附试验对材料的体外抗凝血性试验表明将具有“类肝素”生物活性的磺酸根离子通过ＰＥＯ为“间隔臂”固定在聚醚氨酯上,不仅可以有效地阻抗血小板的粘附、活化,还可以有效地阻断内外源凝血途径,具有较好的血液相容性．     

Synthesis,characterization, and thermal properties of biodegradable polyetheresteramide copolymers based on 11-aminoundecanoic acid

In this work, new aliphatic polyetheresteramide copolymers based on e-caprolactone, 11-aminoundecanoic acid, and poly(ethylene glycol) (PEG) were synthesized by the melt polycondensation method. The copolymers obtained were characterized by ¹H NMR, differential scanning calorimetry, thermogravimetric analysis/differential thermogravimetry, and wide-angle X-ray diffraction. Water absorption and hydrolytic degradation behavior was also studied. With the increase in PEG content, water absorption and the hydrolytic degradation rate increased accordingly.     

Effect of different polyethers on surface and thermal properties of poly(urethane-siloxane) copolymers modified with side-chain siloxane

Poly(urethane-dimethylsiloxane) (PU-PDMS) copolymers with 4,4′-methylenebis(cyclohexyl isocyanate), different polyethers i.e., poly(oxytetramethylene)diol, poly(ethylene glycol), poly(propylene glycol), and α,ω-dihydroxy terminated polydimethylsiloxane extended with 1,4-butanediol in two-step solution polymerization were obtained. The PU-PDMS were modified using 1.25 mol% of polydimethylsiloxane which was incorporated into main polyurethane backbone as a side chain. The structure of the synthesized PU-PDMS was confirmed by FTIR as well as ¹H and ¹³C-NMR spectroscopy. The effect of different soft segments on free surface energy (FSE) components and thermal stability of poly(urethane-siloxane) copolymers was investigated. The activation energy of the thermal degradation of PU-PDMS using isoconversional methods (Ozawa–Flynn–Wall and Friedman) was calculated. It was concluded that molecular mass, thermal stability, and FSE of PU-PDMS copolymers depend on polyol used. The apparent activation energy at first step of degradation in nitrogen generally increases with the extent of conversion which may result from complex mechanism related to formation of decomposition products. Hydrophobic character of side-chain siloxane on surface properties of the PU-PDMS coatings was confirmed. The obtained coatings are generally soft with the relative hardness in the range of 0.120–0.027.     

Synthesis and characterization of biodegradable aliphatic copolyesters with poly(ethylene oxide) soft segments

A series of multiblock poly(ether-ester)s based on poly(butylene succinate) (PBS) as the hard segments and hydrophilic poly(ethylene oxide) (PEO) as the soft segments was synthesized with the aim of developing degradable polymers which could combine the mechanical properties of high performance elastomers with those of flexible plastics. The aliphatic poly(ether-ester)s were synthesized by the catalyzed two-step transesterification reaction of dimethyl succinate, 1,4-butanediol and α,ω-hydroxyl terminated poly(ethylene oxide) (PEO, = 1000 g/mol) in bulk. The content of soft PEO segments in the polymer chains was varied from about 10 to 50 mass%. The effect of the introduction of the soft PEO segments on the structure, thermal and physical properties, as well as on the biodegradation properties was investigated. The composition and structure of these aliphatic segmented copolyesters were determined by ¹H NMR spectroscopy. The molecular weights of the polyesters were verified by gel permeation chromatography (GPC), as well as by viscometry of dilute solutions and polymer melts. The thermal properties were investigated using differential scanning calorimetry (DSC). The degree of crystallinity was determined by means of DSC and wide-angle X-ray scattering. A depression of melting temperature and a reduction of crystallinity of the hard segments with increasing content of PEO segments were observed. Biodegradation of the synthesized copolyesters, estimated in enzymatic degradation tests in phosphate buffer solution with Candida rugosa lipase at 37 °C was compared with hydrolytic degradation in the buffer solution. The weight losses of the samples were in the range from 2 to 10 mass%. GPC analysis confirmed that there were significant changes in molecular weight of copolyesters with higher content of PEO segments, up to 40% of initial values. This leads to conclusion that degradation mechanism of the poly(ether-ester)s based on PEO segments occurs through bulk degradation in addition to surface erosion.     

Modification of polyester fibrous materials with surface barrier discharge for making them more hydrophilic

The possibility of using surface barrier discharge for the surface modification of polyester fabrics with the aim of making them more hydrophilic was studied. The action of surface-barrier discharge leads to the formation of hydrophilic oxygen-containing groups on the surface of polyester fabrics owing to weak degradation of poly(ethylene terephthalate) macromolecules, and the thread surface becomes rougher on the nanolevel. This leads to a considerable decrease in the contact angle and to an increase in the wettability of the polyester fabric, i.e., the fabric becomes considerably more hydrophilic. Modification of the polyether fabric with surface barrier discharge does not cause appreciable decrease in the strength and breaking elongation of the material.