Characterization of amphiphilic hydrocarbon modified Poly(ethylene glycol) synthesized through ring-opening reaction of 2-(1-octadecenyl)succinic anhydride

Poly(ethylene glycol) (PEG) triblock and diblock amphiphilic block copolymers were synthesized from poly(ethylene glycol) and poly(ethylene glycol) monomethyl ether, respectively. The hydroxyl groups of PEG readily react with 2-(1-octadecenyl) succinic anhydride (OSA) at 140 °C through ring-opening reaction of the succinic anhydride. Both the PEG-OSA diblock and triblock copolymers are produced without use of any solvent or catalyst. The molecular structure of the copolymers was characterized by ¹H NMR and FTIR spectroscopy, and the thermal properties by DSC. The behavior of the copolymers in selective and nonselective solvents was studied by ¹H NMR spectroscopy in deuterium oxide and d-chloroform. The aggregation of the polymers in water was studied with a particle size analyzer and a transmission electron microscope (TEM) in bright field mode. The results show that the hydrophobic C₁₈ chain with intramolecular succinic anhydride linker can be attached to the hydrophilic PEG chain, an ester bond forming between the blocks. The copolymers exhibit flexible, liquid-like hydrophobic blocks even in water, which is a nonsolvent for OSA. PEG-OSA block copolymers self-organize in water, forming micellar polymer aggregates in nanoscale.     

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.     

Shape Memory Properties in Poly(ethylene oxide)–Poly(ethylene terephthalate) Copolymers

Memory effects of several copolymers of poly(ethylene oxide) (PEO) and poly(ethylene terephthalate) (PET) were illustrated with photos, determined with shrinkage experiments and characterized by the recovery of samples to their original figures. Copolymers of appropriate composition could undertake an approximately full recovery which is tightly related to the annealing temperature at which shrinkage of samples occurs to some extent. Melting and recrystallization of PEO segments may be responsible for the memory effect. The memory properties of samples almost kept unchanged after many fatigue cycles (e.g. 15–20 cycles), which could make these copolymers useful in practical applications as novel shape memory materials. © 1997 John Wiley & Sons, Ltd.     

Synthesis and characterization of novel biodegradable copolyesters by transreaction of poly(ethylene terephthalate) with copoly(succinic anhydride/ethylene oxide)

Poly(ethylene terephthalate)/copoly(succinic anhydride/ethylene oxide) copolymers, (PET/PES copolymers) were synthesized by the transreaction between PET and PES and characterized with GPC, ¹H NMR, and DSC. Most of the copolymers obtained were random copolymers. The films cast of these copolymers were transparent. The thermal, mechanical properties, and biodegradability of the copolymers obtained were studied with respect to the composition and lengths of aliphatic and aromatic units in the copolymers. In the copolymers having high PET content, the melting points, due to the PET segment, were observed by DSC measurement, although the fusion heats of the copolymers were small. The enzymatic hydrolyzability by a lipase from Rhizopus arrhizus and biodegradability by activated sludge of the copolymers decreased with an increase in PET content. When the length of succinic acid unit in the copolymer was below 2, the hydrolyzability of the copolymers decreased considerably. The tensile strengths of the cast films prepared from the copolymers synthesized by the transreaction increased with an increase in PET content, whereas, the elongations at break decreased. Their tensile strengths were half, and the elongations were double compared to those of PET homopolymer film. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4478–4489, 2000     

Photocurable biodegradable poly(ɛ-caprolactone)/poly(ethylene glycol) multiblock copolymers showing shape-memory properties

Biodegradable multiblock copolymers were synthesized by a polycondensation of poly(ɛ-caprolactone) (PCL) diols of molecular weight (MW)=3,000 and poly(ethylene glycol)s (PEG) of MW=3,000 with 4,4′-(adipoyldioxy)dicinnamic acid (CAC) dichloride as a chain extender in diphenyl ether at 180 °C for 2 h, and were characterized by GPC, ¹H-NMR, FTIR, UV, DSC, and WAXS. These photosensitive copolymers were irradiated by a 400-W high-pressure mercury lamp (λ>280 nm) from 5–60 min to form a network structure. The gel contents increased with irradiation time, and attained ca. 90% after 60 min for all copolymers. The degree of swelling in a distilled water at ambient temperature, and the rate of degradation in a phosphate buffer solution (pH 7.2) at 37 °C increased with increasing PEG components. The shape-memory tests were performed by a cyclic thermomechanical experiments for the photocured CAC/PCL/PEG (75/25) films. The film with a gel content of 57% showed the best shape-memory property with strain fixity rate of 100% and strain recovery rate of 88%.     

Recovery as a measure of oriented crystalline structure in poly(ether ester)s based on poly(ethylene oxide) and poly(ethylene terephthalate) used as shape memory polymers

Poly(ether ester)s consisting of poly(ethylene oxide) and poly(ethylene terephthalate) segments, EOET copolymers, could be used as shape memory polymers (SMP). Crystalline structural characters of the copolymers during the memory process were investigated by dynamic mechanical analysis, differential scanning calorimeter, wide-angle X-ray diffraction, polarizing microscopy, and recovery measurements. PEO crystals in stretched EOET copolymer preferentially oriented along fiber axis or stretch direction. During stretching, the structure of the copolymer undertake a transformation from spherulite to fiber, resulting in a crystalline morphology similar to shish-kebab, and recovery properties of stretched EOET samples were dependent on as-described crystalline structural characters that can be influenced by draw ratio. Driving forces for contraction come from the oriented chains, and only oriented or extended chains can be contributive to the recovery of deformation; these extended chains involve both crystalline and amorphous segments. The recovery process in shape memory behavior was noticed to be deorientation of oriented chains due to thermodynamic entropy effect, and was divided into three stages. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 101–112, 1999     

In vitro ageing and degradation of PEG-PLA diblock copolymer-based nanoparticles

Diblock copolymers composed of poly(oxy-ethylene) (POE) and poly(dl-lactic acid) segments were synthesized by anionic polymerization of d,l-lactide using the oxyanion formed by reaction of the monohydroxyl monomethoxy-poly(ethylene glycol) on sodium hydride. For comparison, a similar copolymer was prepared by using tin octoate to catalyze the lactide polymerization. The copolymers were used to make nanoparticles, which were stored at 4 °C. After a few months under these storage conditions, a dramatic decrease of the poly(ethylene glycol) content was observed, however, the mean diameter of the nanoparticles was not affected. The degradation of the nanoparticles was investigated in vitro under conditions selected to mimic physiological conditions. Changes of characteristics were monitored by ¹H NMR, SEC, DLLS and CZE on nanoparticles and/or on the degradation by-products dissolved in the ageing medium. According to their nanometric dimensions, the microparticles degraded very slowly and there was no difference in behaviour between the sodium hydride and the stannous octoate-derived copolymers.     

New architectures of poly(ethylene glycol) and poly(methylthiirane) in block copolymers

Two synthetic ways were experimented to prepare new architectures of block copolymers made of poly(ethylene glycol) (PEG) and poly(methylthiirane). The coupling of both blocks conveniently end-capped as well as anionic polymerization of methylthiirane initiated by PEG-thiols gave readily the copolymers. Their characterization by ¹H NMR, SEC and IR confirmed the expected structures.     

Synthesis and characterization of polyurethane-g-chitosan

The present work presents a study on the grafting of polyurethane onto chitosan. Prepolymers (polyurethanes) were obtained by condensation reactions between poly(ethylene glycol) of two different molar masses and isophorone diisocyanate. Characterization of graft copolymers was performed by infrared spectroscopy (IR) and ¹³C Nuclear Magnetic Resonance in the solid state (¹³C NMR). Evidences of grafting were obtained by IR from the absorbance increase of relative intensity of NH and CO bands, with respect to chitosan. The degree of NH₂ substitution by urea groups observed from 0.12 to 0.59 was estimated from NMR data. The graft copolymers exhibited different solubility behavior as a function of degree of substitution, such as partial solubility, gelation or swelling in diluted acetic acid, and swelling in water, dimethylsulfoxide and acetic acid/sodium acetate.     

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.     

A water-soluble PPDO/PEG alternating multiblock copolymer: Synthesis, characterization, and its gel-sol transition behavior

Biodegradable and nontoxic alternating multiblock copolymers based on poly (p-dioxanone) (PPDO) and poly (ethylene glycol) (PEG) were synthesized by the coupling reaction of two bifunctional prepolymers, a dihydroxyl-terminated PPDO and dicarboxylated PEG. The prepolymers and the resulting PPDO/PEG multiblock copolymers were characterized by various analytical techniques such as FT-IR, ¹H NMR, GPC, DSC and TG. At high concentration levels above critical gelation concentration (CGC), the aqueous solution of copolymers formed a gel. Temperature-sensitive gel to sol transition behaviors were investigated by the test tube inverting method. Dynamic light scattering (DLS) was used to investigate the micelle of copolymers, whose association probably caused the gelation of the system. Therefore, this novel copolymer has a great potential in injectable drug-delivery system for long-term delivery of drugs.     

Structure and properties of new polyester elastomers composed of poly(trimethylene terephthalate) and poly(ethylene oxide)

Series of PTT-b-PEO copolymers with different composition of rigid PTT and PEO flexible segments were synthesized from dimethyl terephthalate (DMT), 1,3-propanediol (PDO), poly(ethylene glycol) (PEG, M_n = 1000 g/mol) in a two stage process involving transesterification and polycondensation in the melt. The weight fraction of flexible segments was varied between 20 and 70 wt%. The molecular structure of synthesized copolymers was confirmed by ¹H NMR and ¹³C NMR spectroscopy. The superstructure of these polymers was characterized by DSC, DMTA, WAXS and SAXS measurements. It was observed that domains of three types can exist in PTT-b-PEOT copolymers: semi-crystalline PTT, amorphous PEO rich phase (amorphous PEO/PTT blended phase) and semi-crystalline PEO phase. Semi-crystalline PEO phase was observed only at temperature below 0 °C for sample containing the highest concentration of PEO segment. The phase structure, thermal and mechanical properties are effected by copolymer composition. The copolymers containing 30÷70 wt% of PEO segment posses good thermoplastic elastomers properties with high thermal stability. Hardness and tensile strength rise with increase of PTT content in copolymers.     

Parameters affecting transition temperatures of poly(lactic acid‐co‐polydiols) copolymer‐based polyester urethanes and their shape memory behavior

A series of polyester urethanes (PEUs) comprising poly(lactic acid‐co‐polydiol) copolymers as a soft segment, 4,4′‐diphenylmethane diisocyanate (MDI) and 1,4‐butanediol (BDO) as a hard segment were systematically synthesized. Soft segments, which were block copolymers of L ‐lactide (LA) and polydiols such as poly(ethylene glycol) and poly(trimethylene ether glycol), were prepared via ring opening polymerization. Glass transition temperatures (T_g) of the obtained PEUs were found strongly dependent on properties of copolymer soft segments. By simply changing composition ratio, type and molecular weight of polydiols in the soft segment preparation step, T_g of PEU can be varied in the broad range of 0–57°C. The synthesized PEUs exhibited shape memory behavior at their transition temperatures. PEUs with hard segment ratio higher than 65 mole percent showed good shape recovery. These findings suggested that it is important to manipulate molecular structure of the copolymer soft segment for a desirable transition temperature and design optimal soft to hard segment ratio in PEU for good shape recovery. Copyright © 2011 John Wiley & Sons, Ltd.     

The Synthesis of Poly(ethylene oxide)-Block-Polybutylacrylate

ＴｈｅＳｙｎｔｈｅｓｉｓｏｆＰｏｌｙ（ｅｔｈｙｌｅｎｅｏｘｉｄｅ）┐Ｂｌｏｃｋ┐Ｐｏｌｙｂｕｔｙｌａｃｒｙｌａｔｅ＊＊ＳｕｐｐｏｒｔｅｄｂｙｔｈｅＮａｔｉｏｎａｌＮａｔｕｒａｌＳｃｉｅｎｃｅＦｏｕｎｄａｔｉｏｎｏｆＣｈｉｎａａｎｄＤｏｃｔｏｒａｌｆｏ...     

Synthesis and micelle formation of triblock copolymers of poly(methyl methacrylate)-b-poly(ethylene oxide)-b-poly(methyl methacrylate) in aqueous solution

Amphiphilic triblock copolymers of poly(methyl methacrylate)-b-poly(ethylene oxide)-b-poly(methyl methacrylate) (PMMA-b-PEO-b-PMMA) with well-defined structure were synthesized via atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) initiated by the PEO macroinitiator. The macroinitiator and triblock copolymer with different PMMA and/or PEO block lengths were characterized with ¹H and ¹³C NMR and gel permeation chromatography (GPC). The micelle formed by these triblock copolymers in aqueous solutions was detected by fluorescence excitation and emission spectra of pyrene probe. The critical micelle concentration (CMC) ranged from 0.0019 to 0.016 mg/mL and increased with increasing PMMA block length, while the PEO block length had less effect on the CMC. The partition constant K_v for pyrene in the micelle and in aqueous solution was about 10⁵. The triblock copolymer appeared to form the micelles with hydrophobic PMMA core and hydrophilic PEO loop chain corona. The hydrodynamic radius R_h,app of the micelle measured with dynamic light scattering (DLS) ranged from 17.3 to 24.0 nm and increased with increasing PEO block length to form thicker corona. The spherical shape of the micelle of the triblock copolymers was observed with an atomic force microscope (AFM). Increasing hydrophobic PMMA block length effectively promoted the micelle formation in aqueous solutions, but the micelles were stable even only with short PMMA blocks.     

Preparation of degradable polypropylene by an addition of poly(ethylene oxide) microcapsule containing TiO2 part II. Modification of calcium phosphate on the TiO2 surface and its effect

To prepare a novel photo-degradable polypropylene (PP) with a higher degradation rate, a PP composite containing a poly(ethylene oxide) (PEO)/modified TiO₂ microcapsule was prepared. The modification of the TiO₂ was performed by the synthesis of octacalcium phosphate intercalated with succinic acid ion (OCPC) under various Ca/P molar ratio conditions. It was found that the synthesis conditions of the Ca/P = 3.5 and 3.6 M ratios were suitable to prepare the OCPC. However, the microscopic composition on the TiO₂ surface was different between these Ca/P conditions and affected the PP photo-degradation rate in the PP/PEO/modified TiO₂ composite. It was found from the Fourier Transform Infrared (IR) and the tensile testing measurements that the existence of the OCPC covering material on the TiO₂ surface brought about the higher PP photo-degradation rate. The facilitation behavior of the degradation was due to the release of the acid species (succinic acid ion) from the OCPC in the degradation process. In addition, the higher coverage of the OCPC on the TiO₂ surface brought about an induction period for the degradation.     

The Effect of Copolymer Composition on Surface Free‐Energy of Poly(2‐Hydroxyethyl Methacrylate–Crotonic Acid) Copolymers

Abstract

Poly(2‐hydroxyethyl methacrylate–crotonic acid) P(HEMA/CrA) copolymers with varying compositions were prepared from ternary mixtures of 2‐hydroxyethyl methacrylate (HEMA)/crotonic acid (CrA)/water by using ⁶⁰Co γ‐rays. The wetting forces were determined according to the Wilhelmy Plate Technique. Di‐iodomethane, ethylene glycol, and formamide were used as probe liquids. Lifshitz–van der Waals surface energy components, Lewis acid–base surface components, and total surface energies were calculated using van Oss et al. methodology. It was determined that Lifshitz–van der Waals component (γ_S ^LW) of the copolymers did not differ much from the copolymer composition. However, the electron‐donor surface free energy components (γ_S ^?) of the copolymers were decreased considerably with the increase of the CrA content of the copolymers, the surfaces of these copolymers were still found to have a basic character.     

SYNTHESIS OF NOVEL BLOCK COPOLYMERS OF POLY(3-HYDROXYBUTYRIC ACID)WITH POLY(ETHYLENE GLYCOL)THROUGH ANIONIC POLYMERISATION

A novel kind of copolymer with ABA-type block structure was synthesized by anionic ring-openingpolymerization of β-butyrolactone (β-BL) in the presence of a PEG-based dicarboxylates as macroinitiators which wereprepared by the esterification of aliphatic cyclic anhydride and poly(ethylene glycol) (PEG) oligomers (M_n=2000, 4000 and6000) and conversion of potassium dicarboxylates. The resultant copolymers as well as the intermediates were characterizedby IR,~1H-NMR and GPC.     

聚乳酸-b-聚(N~ε-苄氧羰基-L-赖氨酸)-b-聚乙二醇的合成与表征

用端氨基聚乳酸做引发剂,在DMF中引发Nε-苄氧羰基-L-赖氨酸酐(Lys(Z)-NCA)聚合,合成了端氨基聚(Nε-苄氧羰基-L-赖氨酸)-b-聚乳酸两嵌段共聚物.以端羧基聚乙二醇经NHS活化与端氨基聚(Nε-苄氧羰基-L-赖氨酸)-b-聚乳酸偶联,合成了聚(乳酸-b-Nε-苄氧羰基-L-赖氨酸-b-乙二醇)三嵌段聚合物.利用IR、1H-NMR、GPC和TEM对它们的结构、形态进行了表征,结果表明,所合成的分子量可控、分子量分布窄(Mw/Mn=1.07)的嵌段共聚物,酰化反应产率达70%以上.同时聚乙二醇和Nε-苄氧羰基-L-赖氨酸被引入到聚乳酸主链中,在聚合物侧链脱保护后有望改善聚乳酸的细胞亲和性。     

Methoxy poly(ethylene glycol)-b-poly(valerolactone) diblock polymeric micelles for enhanced encapsulation and protection of camptothecin

Amphiphilic block copolymers, methoxy poly(ethylene glycol)-b-poly(valerolactone) (mPEG-b-PVL), were synthesized via ring opening polymerization of δ-valerolactone in the presence of methoxy poly(ethylene glycol) (mPEG). The copolymers form micelle-like nanoparticles by their amphiphilic characteristics and their structures were examined by Nuclear Magnetic Resonance (NMR). The sizes of nanoparticles ranged from 60 to 120 nm as measured by dynamic light scattering detection, and were larger with higher molecular weight of the copolymers. The Critical Micelle Concentration (CMC) of these nanoparticles in water decreased with increasing molecular weight of hydrophobic segment. Stability analysis showed that the micellar solutions maintain their sizes at 37 °C for six weeks without aggregation or dissociation. The lyophilization method was better than the evaporation method when camptothecin (CPT) was incorporated to the micelles. The former method yielded higher CPT loading efficiency and lower aggregation. The loading efficiency of CPT could be more than 96% and a steady release rate of CPT was kept for twenty six days. Moreover, the mPEG-b-PVL polymeric micelles offered good protection of CPT lactone form at 37 °C for sixteen days. The copolymers showed no cytotoxicity towards L929 mouse muscular cells when incubated for one day. Taken together, the mPEG-b-PVL copolymer has potential to be used for the delivery of CPT or other similar drugs.