Preparation of poly (ethylene glycol) acrylate grafted polystyrene resin for solid-phase peptide synthesis

The solid-phase synthesis resin with high loading capacity was prepared through grafting poly (ethylene glycol) acrylate monomer from Merrifield resins via activators generated by electron transfer atom transfer radical polymerization. The grafted resins demonstrate well-swellability in both polar and nonpolar solvent such as dichloromethane, dimethylformamide, ethanol, tetrahydrofuran, acetonitrile, methanol and water. Particularly, the swelling ability of the grafted resin has reached two-fold of Merrifield resin in the polar solvent such as acetonitrile, methanol and water, and it enable high functional loadings up to 0.5–1.2 mmol g⁻¹ compared with the conventional polystyrene-grafting-poly (ethylene glycol) (0.15–0.25 mmol g⁻¹). This resin was derived to be used for synthesis of a difficult sequence-acyl carrier protein fragment 65-74 (ACP 65-74). The quantity and purity of peptide obtained from the grafted resin were higher than when the commercial Wang resin was used. The synthesis efficiency enhanced with the increase of grafting chains’ length within the range of hydroxyl capacity at 0.5–1.0 mmol g⁻¹. It was relative that the longer grafting chains were favor to suppress the hydrophobicity of the Merrifield resin.     

Novel Synthesis of Reactive Poly(ethylene glycol) grafted Poly(L-lactide) via Two Step Polymerizations

Summary Novel poly(L-lactide)-graft-poly(ethylene glycol) having reactive group at the end of grafted chain was prepared by two step polymerizations: ring-opening polymerization of L-lactide and 1,2-epoxy-5-hexene followed by radical polymerization of the product of ring-opening reaction and poly(ethylene glycol) methacrylate. Al(Et)₃·0.5H₂O and AIBN were used as catalyst and initiator for the two step polymerizations respectively. The structure of the synthesized polymers was also characterized.     

Synthesis and Characterization of Poly(ethylene glycol) grafted Poly(ε-Caprolactone)

Summary A new graft copolymer, poly(ε-caprolactone) (PCL) grafted with poly(ethylene glycol) (PEG), was prepared by one-pot synthesis of ε-caprolactone and modified PEG. Aluminium isopropoxide or potassium tert-butoxide was used as a catalyst for the ring-opening polymerization. Polymerization using potassium tert-butoxide as a catalyst showed very effective graft reaction of PEG onto poly(ε-caprolactone). A slight decrease in the melting temperature was observed with the increase of the PEG graft frequency. Interestingly, considerable changes were observed on the surface property by the introducing PEG side chains compared to that of PCL homopolymer. Measurements of water contact angle showed that the hydrophilic surface of the polymer could be obtained even at a low graft frequency of PEG.     

Conformation of oligo(ethylene glycol) grafted polystyrene in dilute aqueous solutions

Temperature induced conformational changes of poly(p-oligo(ethylene glycol) styrene) (POEGS) in aqueous solutions were investigated by small angle neutron scattering (SANS), neutron transmission and dynamic light scattering (DLS). The molecular weight of the polymer studied was 9400 g/mol with a polydispersity index of 1.18 and each repeat unit of the polymer had four ethylene glycol monomer segments. The polymer was water soluble due to the hydrophilicity of the OEG side chains and these solutions showed lower critical solution temperature (LCST) depending on the concentration of the polymer. Measurements of solution behavior were made as a function of temperature in the range of 25-55 °C for three polymer concentrations (0.1 wt%, 0.3 wt%, and 1.8 wt%). Neutron transmission measurements were used to monitor the amount of polymer which precipitated or remained in solution above the cloud point temperature (T_CP). DLS revealed the presence of large clusters in all solutions both below and above T_CP while SANS provided information on the structure and interactions between individual chains. It was found that in the homogeneous region below T_CP the shape of individual polymers in solution was close to ellipsoidal with the dimensions R_a = 37 Å and R_b = 14 Å and was virtually independent of temperature. The SANS data taken for the most concentrated solution studied (1.8 wt%) were fit to the ellipsoidal model with attractive interactions which were approximated by the Ornstein-Zernike function with a temperature-dependent correlation length in the range of 24-49 Å. The collapse of individual polymers to spherical globules with the radius of 15 Å above T_CP was observed.     

The synthesis and characterization of poly(ethylene glycol) grafted on pullulan

The pullulans grafted with poly(ethylene glycol) with different degrees of substitution (DS: 0.02–0.2) are synthesized by reaction of pullulan and poly(ethylene glycol) terminated with carboxylic acid. The structure of the resulting modified pullulans is characterized with ¹H‐NMR and FTIR spectra. The DS of the products increase with the amount of the poly(ethylene glycol) added. The appearances of the products change considerably and the solubility in organic solvent is enhanced visibly. It was found that pullulan derivative is biodegradable. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1217–1221, 2004     

Hydrophilic polymer supports grafted by poly(ethylene glycol) derivatives via atom transfer radical polymerization

In this study, a newly structured hydrophilic polymer supports are prepared by the chemical modification (grafting) of the polystyrene-based preformed beads via atom transfer radical polymerization (ATRP) employing the CuBr/PMDETA catalyst system. Hydrophilic monomers including N,N-dimethylacrylamide (DMA) and poly(ethylene glycol) (PEG) macromonomers were grafted onto Merrifield type resin. Based on optical microscopic data, the particle sizes of the resins were increased in the order of 10 μm after the polymerization. This increment indicated that monomers are grafted not only to the particle surface but also to within a polymer matrix. These resins demonstrate well-swellability in polar solvent, and they enable high functional loadings up to 0.7-1.8 mmol g⁻¹. The high loading capacity in polar solvents and favorable mechanical properties of resins render them to have great potential applications in peptide and oligonucletide syntheses.     

Surface modification of poly(ethylene terephthalate) film by coating with poly(ethylene glycol)‐grafted polystyrene

The poly(ethylene glycol) (PEG)‐grafted styrene (St) copolymer, which was formed as a nanosphere, was used as an agent to modify the surface of poly(ethylene terephthalate) (PET) film. The graft copolymer was dissolved into chloroform and coated onto the PET film by dip–coating method. The coated amount depends on the content ratios of PEG and St, the solution concentration, and the coating cycles. The graft copolymers having a low molecular weight of PEG‐ or St‐rich content was fairly stable on washing in sodium dodecyl sulfate (SDS) aqueous solution. It was confirmed that the PET surface easily altered its surface property by the coating of the graft copolymers. The contact angles of the films coated with the graft copolymers were very high (ca. 105–120°). The coated film has good antistatic electric property, which agreed with PEG content. The best condition of coating is a one‐cycle coating of 1% (w/v) graft copolymer solution. The coated surface had water‐repellency and antistatic electric property at the same time. The graft copolymer consisted of a PEG macromonomer; St was successfully coated onto PET surfaces, and the desirable properties of both of PEG macromonomer and PSt were exhibited as a novel function of the coated PE film. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1524–1530, 1999     

Poly(ethylene oxide) grafted onto polystyrene-divinylbenzene macroporous resins. Covalent binding of mercuric chloride

Chelating resins selective for mercuric chloride have been prepared by the reaction between chloromethylated macroporous styrene-divinylbenzene copolymers (PS-DVB) and monomethoxy-polyoxyethylenes of three different molecular weights (M_w = 164, 350 and 750). It has been shown that the degree of grafting on the PS-DVB matrix is limited by the steric hindrance of the initially grafted polymeric coils. These resins bind mercuric chloride by forming polycomplexes with one mercury atom for each four ethylene oxide units. This stoichiometry is independent of the chain length, in contrast to the case observed with poly(ethylene oxide) (PEO) in water or ethanolic solution. Infrared spectroscopy and anion effects confirm that the complexed species is covalent mercury and not any ionic form. ¹H NMR experiments, using the free induction decay technique on a wet resin containing the longer PEO chain at the maximum ratio of grafting, indicate that 77% of the PEO hydrogens are mobile at room temperature and become rigid in the complex.     

不同PEG含量对PLA/PEG共混物结晶动力学的影响

采用溶液共混法制备了一系列不同配比的聚乳酸(PLA)/聚乙二醇(PEG)共混物。通过偏光显微镜(POM)、扫描电镜(SEM)和差式扫描量热仪(DSC)研究了不同PEG含量的PLA/PEG共混物在不同结晶温度下,聚乳酸的晶体形貌、球晶生长速率及热力学性能。研究发现,PEG能够显著提高聚乳酸球晶的生长速率。当PEG含量为60%时,PLA/PEG共混物中聚乳酸球晶的生长速率最快,达到23.6μm/min,比纯聚乳酸的最快球晶生长速率(0.5μm/min)高47倍。但是,当PEG含量高于60%时,聚乳酸球晶的生长速率有所降低。同时,PLA/PEG共混物中聚乳酸球晶速率随结晶温度变化的取向,均向低温移动。另外,PLA/PEG共混物中聚乳酸球晶呈现环状花纹。DSC测试结果表明,随着PEG含量的增加,PLA/PEG共混物的玻璃化转变温度明显降低。     

Miscibility of polystyrene with poly(ethylene oxide) and poly(ethylene glycol)

The intrinsic viscosity of polystyrene–poly(ethylene oxide) (PS–PEO) and PS–poly(ethylene glycol) (PEG) blends have been measured in benzene as a function of blend composition for various molecular weights of PEO and PEG at 303.15 K. The compatibility of polymer pairs in solution were determined on the basis of the interaction parameter term, Δb, and the difference between the experimental and theoretical weight-average intrinsic viscosities of the two polymers, Δ[η]. The theoretical weight-average intrinsic viscosities were calculated by interpolation of the individual intrinsic viscosities of the blend components. The compatibility data based on [η] determined by a single specific viscosity measurement, as a quick method for the determination of the intrinsic viscosity, were compared with that obtained from [η] determined via the Huggins equation. The effect of molecular weights of the blend components and the polymer structure on the extent of compatibility was studied. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1471–1482, 1998     

单甲氧基聚乙二醇氨基的制备

通过两步反应制备了相对分子质量(简称分子量)为5 000的单甲氧基聚乙二醇氨基(m PEG5k-EDA)。首先以单甲氧基聚乙二醇5 000(m PEG5k)和对甲苯磺酰氯(p-Ts Cl)为原料,反应得到活性中间体m PEG5k-OTs,然后通过与乙二胺的亲核取代反应获得目标产物,并通过正交实验确定了最佳反应条件:m PEG5k-OTs与乙二胺的摩尔比为1∶25、反应温度为80℃和反应时间为24 h。产物和中间体的结构通过IR和1HNMR进行表征,并通过SDS-PAGE碘染色法检测产物分子量的变化情况。结果表明,通过该方法能简便快捷地制备m PEG5k-EDA,在最优实验条件下,目标产物的总收率高达76.8%,且SDS-PAGE检测表明,产物纯度较高,不含交联副产物。     

Injectable gel: Poly(ethylene glycol)-sebacic acid polyester

In order to develop an injectable material for drug delivery that has both formulation advantages of a sol-to-gel transition system and minimal burst release of a drug, a soft thermogel of poly(ethylene glycol)-sebacic acid polyester was synthesized. The polymer aqueous solution (25 wt%) undergoes ‘clear sol-to-gel’ transition as the temperature increases from 5 to 65 °C. The drug can be mixed in a low viscous sol state at low temperature (<15 °C). In particular, the thermogel is soft enough to be injected through a 21-gauge syringe needle even as a gel state. The model hydrophilic drug, FITC-dextran (molecular weight: 40,000 Da), was released from the gel over 24 h. The biodegradable poly(ethylene glycol)-sebacic acid polyester soft thermogel is believed to be promising for the hydrophilic drug delivery where an initial burst of a drug might be a concern.     

Facile and controllable synthesis of hybrid silica nanoparticles densely grafted with poly(ethylene glycol)

We report that a mixture of good and poor solvents greatly enhances the grafting density of nanosized silica grafted with poly(ethylene glycol) (PEG ) by the ‘grafting to’ method. Methoxypolyethylene glycol (MPEG ) (molecular weight 750, 2000 and 4000 g mol^?1) was modified in a controlled manner to prepare epoxide terminated PEG (MPEG‐EO ). Silica nanoparticles were modified with N ‐(2‐aminoethy)‐3‐aminopropylmethyldimethoxysilane through the silanization coupling reaction to obtain a well‐defined siloxane structure. MPEG‐EO was coupled to the modified silica by the reaction of their terminal groups in a mixed solvent (n ‐decane/toluene). The grafting density of MPEG‐EO was found to be controlled by the concentration of MPEG‐EO and the ratio of n ‐decane to toluene in the grafting system. Based on TGA , the maximum grafting density was found to be about 2.8, 1.47 and 0.76 chains nm^?2 for molecular weights of 750, 2000 and 4000, respectively, which is extremely high compared to previous reports. This high grafting density can be explained by the decreased chain dimension of PEG in the presence of the poor solvent. The method can be applied to other nanoparticles and polymers which can greatly enhance the application of SiO₂ nanocomposites. © 2017 Society of Chemical Industry     

Synthesis,characterization and application of tetraethylene glycol diacrylate crosslinked polystyrene support for gel phase peptide synthesis

Styrene and tetraethylene glycol diacrylate (TTEGDA) were copolymerized by the free radical aqueous suspension polymerization technique, employing toluene as the monomer diluent at 80°C. The resulting beads were functionalized by chloromethylation. The copolymer was characterized by IR and high-resolution solid-state ¹³C-NMR techniques. Scanning electron microscopy was employed to observe shape, size, and morphological features of the crosslinked bead copolymer. The swelling capacities of the copolymer were measured in various solvents. Reactivity of the amino functionalized polymer was compared with divinylbenzene-polystyrene (PS) resin. Stability of the copolymer was tested under various peptide synthetic conditions. High capacity chloromethyl TTEGDA-crosslinked PS was employed as a solid support in the synthesis of the hydrophobic peptide Boc(Ala-Leu-Ala)₄-OMe. The coupling and deprotection steps in the synthetic scheme proceeded in near quantitative yields, supporting the positive role of the flexible and hydrophilic crosslinking agent. The fully protected 12-residue peptide was cleaved from the support by a transesterification procedure in 85% overall yield and characterized by thin-layer chromatography, amino acid analysis, and ¹H-NMR. © 1996 John Wiley & Sons, Inc.     

聚乙二醇中共轭烯炔化合物的合成

发展了一种在聚乙二醇介质中末端炔烃与缺电子炔烃选择性生成共轭烯炔化合物的方法。在三苯基膦氯化钯(2mol%)、溴化亚铜(4mol%)、PEG-400(1.0g)和氮气的作用下,1mmol末端炔烃与0.5mmol缺电子炔烃可以顺利地发生交叉偶联反应选择性生成相应的共轭烯炔化合物,该反应产率较高,对环境友好,且催化体系可以适当地重复使用。     

二甲基丙烯酸聚乙二醇酯的RAFT交联聚合行为

采用差示扫描量热(DSC)和动态力学分析(DMA)方法研究二甲基丙烯酸聚乙二醇酯(PEGDMA)的可逆加成-断裂链转移(RAFT)自由基交联聚合,探索了交联单体双键间链段长度和链柔性对RAFT交联聚合动力学及其交联结构的影响.实验发现,随着双键间乙二醇单元数由4增加到9,聚合速率加快,当乙二醇单元数由9增加到14,聚合速率不增反降,这种行为是交联网络密度减小后增长自由基浓度下降和悬挂双键反应活性增加共同作用的结果;双键间链段柔性的增加使RAFT交联聚合速率加快:随双键间链段长度增加,交联网络密度和玻璃化转变温度降低,交联网络的均匀性得到改善.     

Poly(ethylene terephthalate): a solid state condensation process

A new method of solid state condensation of poly(ethylene terephthalate) is described. A low molecular weight pre-polymer with reactive end-groups is annealed at temperatures between 219° and 255°C. Samples with molecular weights from 3000 up to 16 000 are obtained. The materials as polymerized show very sharp melting peaks and high melting temperatures. The equilibrium melting point of PET was determined as 282° ± 2°C, the heat of melting as 26.1 ± 1.0 kJ/mol by suitable extrapolation of the data obtained from samples prepared by varying polymerization time and temperatures.     

Improved Hydrophilicity from Poly(ethylene glycol) in Amphiphilic Conetworks with Poly(dimethylsiloxane)

This paper focuses on the improvement of hydrophicility and water content of poly(dimethylsiloxane) (PDMS) by bonding a hydrophilic macromer, hydroxyl-terminated linear poly(ethylene glycol) (PEG), into a highly hydrophobic macromer, hydroxyl-terminated linear PDMS to prepare amphiphilic conetworks (APCNs) with the crosslinkers, tetraethoxysilane (TEOS) and bis[(3-methyldimethoxysilyl)propyl]-polypropylene oxide (BMPPO), which also functioned as a compatibilizer. Fourier transform infrared results clearly demonstrated the occurrence of the hydrolysis reactions between the terminal hydroxyl groups on the terminal of the two polymer chains and the alkoxy groups in TEOS and BMPPO. Differential scanning calorimetry results and X-ray diffraction obviously showed the presence of the two phases in the conetworks. The contact angle (CA) indicated the wettability of the conetworks increased in the surfaces, that is, CA values decreased significantly from 105° in PDMS to 55° in the PEG/PDMS APCN (10/1 mol ratio), and the swelling degrees of the APCNs increased from ca. 0 to 60 % when the PEG/PDMS mol ratio was larger than 4/1. The APCNs with such high hydrophilicity and the good mechanical properties should be useful as biomaterials.     

聚丁二酸乙二醇酯合成的研究进展

综述了直接酯化聚合法、丁二酸酐开环聚合法、酯交换聚合法、耦合反应法合成聚丁二酸乙二醇酯(PES)的国内外研究进展,着重介绍了丁二酸和乙二醇酯化聚合法合成PES的催化剂和工艺的研究现状,并展望了PES及其合成工艺的发展前景。