Micellization and Thermogelation of Poly(ether urethane)s Comprising Poly(ethylene glycol) and Poly(propylene glycol)

A series of multiblock poly(ether urethane)s comprising poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) segments were synthesized. Their aqueous solutions exhibited thermogelling behavior at critical gelation concentrations (CGC) ranging from 8 to 12 wt%. The composition and structural information of the copolymers were studied by GPC and ¹H NMR. The critical micellization concentration (CMC) and thermodynamic parameters for micelle formation were determined at different temperatures. The temperature response of the copolymer solutions were studied and found to be associated with the composition of the copolymers.     

Poly(ethylene glycol) Surface Coated Magnetic Particles

Summary: A methacrylate‐functionalized poly(ethylene glycol) macromonomer was copolymerized at the surface of methacrylate‐derivatized maghemite nanoparticles. After silylation of the magnetic core with methacryloxypropyltrimethoxysilane, two grafting procedures based on either a direct copolymerization reaction in water or an inverse emulsion polymerization were compared. A direct copolymerization led to low polymer surface amounts, whereas an inverse emulsion process allowed nanocomposite particles containing up to 90 wt.‐% polymer to be obtained.

TEM picture of maghemite‐PEG hybrid particles.     

Poly(ethylene glycol)-based shape-memory polymers

Poly(ethylene glycol) (PEG) blends photo-curable and thermal activated shape-memory polymers (SMPs), with different activation temperature (T_switch), have been synthesized and characterized. PEG blends with different molecular weights were chain-end functionalized with isocyanate ethyl methacrylate and photo-cured with UV lamp. Degree of cross-linking of the blend network, determined by gel content measurement, resulted as higher than 95%. The thermal and thermomechanical properties of these SMPs PEG blends were characterized by differential scanning calorimetry and dynamic mechanical analysis. The shape-memory properties of the networks were quantified using thermomechanical three-point bending experiments and showed strain fixity rates higher than 99% and a minimum strain recovery ratio of 82%.     

Synthesis and Characterization of Calix[4]arene Functionalized Poly(ethylene glycol) Derivatives

Calix[4]arenes with both ligating and methoxy poly(ethylene glycol) groups appended have been synthesized using several approaches, involving the formation of sulfonyl ester groups on the wide rim, Schiff base derivatives on the narrow rim, and thioether groups on both the wide and narrow rims. These new derivatives have been characterized by a combination of infrared and ¹H NMR spectroscopy. Compounds 10 and 11 are insoluble in both water and aqueous poly(ethylene glycol), but the other new compounds are soluble.     

Surface Modification of Carbon Nanotube by Poly(ethylene glycol) for the Preparation of Poly(vinyl alcohol) Nanocomposite

Herein, PEGylated multi-walled carbon nanotube (MWNT) was prepared for the successive fabrication of poly(vinyl alcohol) PVA/MWNT nanocomposite film by solution casting. The surface modified MWNT showed a good colloidal stability in a polar solvent, i.e., water. Also, the PEGylated MWNT had an improved dispersion stability in aqueous PVA solution. The mixture of PEGylated MWNT and PVA dissolved in water was film casted and the dispersion uniformity and corresponding improvement of electrical conductivity were investigated. The electrical conductivity of PVA/modified MWNT composite film was three-fold higher than that of PVA/pristine MWNT composite film due to the much improved distribution uniformity of modified MWNT in PVA matrix.     

Green polymer chemistry: Telechelic poly(ethylene glycol)s via enzymatic catalysis

This article reports our discovery that poly(ethylene glycol) (PEG) can quantitatively be functionalized by transesterification using Candida antarctica lipase B (Novozyme 435) as the catalyst. α‐ω telechelic PEG‐methacrylates and PEG‐acetates were successfully prepared using commercially available PEGs with both narrow and broad molecular weight distribution. ¹H and ¹³C NMR together with MALDI‐TOF mass spectroscopy verified the expected structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3024–3028, 2008     

聚乙二醇单甲醚修饰多壁碳纳米管的研究

多壁碳纳米管(MWNT)经过酸化、酰氯化后与聚乙二醇单甲醚进行接枝反应,实现了碳纳米管的表面修饰。经修饰的MWNT在水中的分散性大大增加。通过FTIR、XPS、Raman、TEM、TGA等手段表征了接枝后产物的化学结构,证明聚乙二醇单甲醚是以共价键的形式接入MWNT表面上的。并利用TGA结果估算出聚乙二醇单甲醚在MWNT表面的接枝密度约为平均每256个碳原子上有一根聚合物链。     

Surface covalent encapsulation of multiwalled carbon nanotubes with poly(acryloyl chloride) grafted poly(ethylene glycol)

Multiwall carbon nanotube (MWNT) was grafted with polyacrylate‐g‐poly (ethylene glycol) via the following two steps. First, hydroxyl groups on the surface of acid‐treated MWNT reacted with linear poly(acryloyl chloride) to generate graft on MWNT; secondly, the remaining acryloyl chloride groups were subjected to esterification with poly(ethylene glycol) leading the grafted chains on the surface of MWNTs. Thus obtained grafted MWNT was characterized using Fourier transform infrared spectrometer, transmission electron microscopy, and X‐ray photoelectron spectroscopy. Thermogravimetric analysis showed that the weight fraction of grafted polymers amounted to 80% of the modified MWNT. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6880–6887, 2006     

Multifunctional Poly(ethylene glycol)s

In the rapidly evolving multidisciplinary field of polymer therapeutics, tailored polymer structures represent the key constituent to explore and harvest the potential of bioactive macromolecular hybrid structures. In light of the recent developments for anticancer drug conjugates, multifunctional polymers are becoming ever more relevant as drug carriers. However, the potentially best suited polymer, poly(ethylene glycol) (PEG), is unfavorable owing to its limited functionality. Therefore, multifunctional linear copolymers (mf‐PEGs) based on ethylene oxide (EO) and appropriate epoxide comonomers are attracting increased attention. Precisely engineered via living anionic polymerization and defined with state‐of‐the‐art characterization techniques—for example real‐time ¹H NMR spectroscopy monitoring of the EO polymerization kinetics—this emerging class of polymers embodies a powerful platform for bio‐ and drug conjugation.     

Stabilization of Silver Nanoparticles by Polyelectrolytes and Poly(ethylene glycol)

Silver nanoparticles of 23 nm size were formed by chemical reduction of silver nitrate in excess of aqueous sodium borohydride. To examine the aggregation behavior in NaCl solutions, they were coated with poly(diallyldimethylammonium chloride), poly(allylamine hydrochloride) and poly(ethylene glycol) by layer‐by‐layer assembly. Silver nanoparticles coated with PDADMAC of both high and low molecular weight revealed the lowest stability independent of salt concentration. Silver nanoparticles coated with PAH and PEG are stable in 0.1 or 0.01 M NaCl, whereas addition of 0.5 M NaCl destroys the colloidal solution. The destruction of silver agglomerates and the increase of monodispersity in the case of PEG coated silver nanoparticles were observed after heating at 90 °C. In contrast, uncoated silver nanoparticles readily agglomerate and precipitate even after heating at 65 °C.

     

Synthesis of Poly(ethylene oxide)s Bearing Functional Groups along the Chain

Well‐defined poly(ethylene oxide)s (PEOs) bearing reactive sites regularly distributed along the chain have been synthesized by the polycondensation of PEO containing a central tertiary amino group with dichloromethane, followed by quaternization with suitable reagents to obtain polyzwitterionic or cationic PEOs with alkyl, allyl, or fluorocarbon pendant groups. The pendant allyl groups have been converted into primary amino groups by reaction with 2‐aminoethanethiol hydrochloride to obtain polyamino‐functionalized PEO.

Polyfunctional PEOs bearing different pendant groups.     

聚乙二醇中1-辛炔的环三聚反应

在绿色反应介质聚乙二醇中,PdCl2／CuCl2催化体系可以顺利地催化1-辛炔发生环三聚反应,区域选择性地生成1,3,5-三己基苯,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．     

Electrostatic Assembly of Poly(ethylene glycol) Nanotubes

Poly(ethylene glycol) (PEG)‐based films, nanotubes, and nanotube arrays were successfully made using layer‐by‐layer (LbL) assembly ion‐containing PEO derivatives on porous templates and planar substrates. PEG nanotubes are challenging to produce because PEG dissolves into solutions and solvents used during nanotube processing, but our techniques circumvent the issue. Nanotube dimensions were verified using microscopy and the average observed diameter was 155 nm. The PEG‐based structures showed remarkable stability in water, salt water, and sodium hydroxide solution.

     

Modification of acrylic bone cements by poly(ethylene glycol) with different molecular weight

The high polymerization temperature of acrylic bone cements can cause arthroplasty failure because of the thermal necrosis of surrounding bone tissue. To reduce this undesired effect we have developed novel acrylic bone cement composites containing a phase change material (PCM). As PCM poly(ethylene glycol) (PEG) of different molecular weight was applied and the effect of its incorporation on curing parameters, mechanical and morphological properties of acrylic bone cement was investigated. A significant decrease in maximum temperature from 65.8°C to 47.4°C and slight increase of setting time were observed. PEG introduction also contributed to the thermal stability of acrylic bone cement increase. SEM investigation of modified bone cement confirmed that the microstructure does not alter considerably because of PEG content. It was found that both PEG addition and incubation test contribute to an inconsiderable decrease in mechanical strength of bone cement. However, the mechanical strength increase can be caused by the fresh bone tissue incorporation into the pores appearing in bone cement. Copyright © 2016 John Wiley & Sons, Ltd.     

Surface Modification of 316L Stainless Steel by Grafting Methoxy Poly(ethylene glycol) to Improve the Biocompatibility

Percutaneous coronary intervention(PCI) has become an important method for the treatment of the patients with coronary heart disease; however, problems, such as vascular endothelial inflammation, late thrombosis, and stent restenosis still exist as a result of poor biocompatibility of the materials. To enhance the biocompatibility, methoxy poly(ethylene glycol)(mPEG) was immobilized on the surface of AISI 316 grade stainless steel(SS)(AISI: American Iron and Steel Institute). First, silanized mPEG was synthesized by the direct coupling of mPEG with 3-isocyanatopropyltriethoxysilane(IPTS) via urethane bonds, and the silanized mPEG was then grafted on the surface of SS that was hydroxylated with piranha solution. The results obtained from contact angle goniometry, X-ray photoelectron spectroscopy(XPS), and atomic force microscopy(AFM) confirm that the mPEG modified steel contained more C and Si and less Fe and Cr on its surface, exhibiting a morphological change and decrease in the contact angle. The biocompatibility of the mPEG modified SS was evaluated with fibrinogen adsorption, platelet activation and adhesion, and human umbilical vein endothelial cell(HUVEC) adhesion. Fibrinogen adsorption, platelet activation, and adhesion were clearly suppressed on the surface-modified steel. In addition, human umbilical vein endothelial cell(HUVEC) could adhere and proliferate on the surface of the mPEG-modified SS. This study indicates that the modification of 316L SS with mPEG could enhance the biocompatibility and provide a primary experimental foundation for the development of next-generation coronary stent materials for clinical application.     

New Poly(propylene glycol)‐ and Poly(ethylene glycol)‐Based Polymer Gelators with L‐Lysine

Summary: New polymer gelators consisting of poly(propylene glycol) or poly(ethylene glycol) and L ‐lysine‐based low‐molecular‐weight gelators have been developed. These polymer gelators were synthesized according to a simple procedure with high reaction yield, and formed organogels in many organic solvents. The organogelation mechanism was proposed from the transmission electron microscopy and FTIR spectroscopy studies.

Structures of the polymer gelators synthesized here.     

Poly(2‐ethyl‐2‐oxazoline) as Alternative for the Stealth Polymer Poly(ethylene glycol): Comparison of in vitro Cytotoxicity and Hemocompatibility

Limitations of PEG in drug delivery have been reported from clinical trials. PEtOx (0.4–40 kDa) as alternative is synthesized by a living, microwave‐assisted polymerization, and is directly compared to PEG of similar molar mass regarding cytotoxicity and hemocompatibility. In short‐term treatments, both types of polymers are well tolerated even at high concentrations. Moderate concentration and molar mass dependent cytotoxic effects occurred only after long‐term incubation at concentrations higher than therapeutic doses. PEtOx possesses not only an easy route of synthesis and beneficial physicochemical characteristics such as low viscosity and high stability, which are advantageous over PEG, but additionally in vitro toxicology comparable to PEG.

     

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

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