聚己内酯－聚乙二醇嵌段共聚物Ⅱ．组成、结晶性同降解性间关系

采用ＤＳＣ法测定了新嵌段共聚物聚己内酯（ＰＣＬ）－聚乙二醇（ＰＥＧ）嵌段共聚物（ＰＣＥ）的结晶性，研究了共聚物的结晶性同组成及降解性的关系．结果表明随着共聚物中ＰＥＧ组分的含量和分子量增加，共聚物的结晶性下降，亲水性提高，降解速度加快．     

聚己内酯－聚乙二醇嵌段共聚物Ⅱ．组成、结晶性同降解性间关系

采用ＤＣＳ法测定了新嵌段共聚物聚己内酯－聚乙二醇嵌段共聚物的结晶性，研究了共聚物的结晶性同组成及降解性的关系。结果表明随着共聚物中ＰＥＧ组分的含量和分子量增加，共聚物的结晶性下降，亲水性提高，降解速度加快。     

Surface properties and drug release behavior of polycaprolactone polyether blend and copolymer

The surface properties of polycaprolactone (PCL)–poly(ethylene glycol) (PEG) block copolymer (PCE) and blend (B-PCE) of PCL and PEG obviously affect the drug release behavior of the polymer. In this paper, both surface properties of PCE and B-PCE are studied and compared by measuring their water sorption and using the contact angle and X-ray photoelectron spectroscopy technique. The effect of the polyether segment content in PCE and B-PCE on hydrophilicity is discussed. The results show that a hydrophilic polyether segment moves towards the surface and enriches on the surface for either PCE or B-PCE. The enrichment content of the polyether segment of PCE and the hydrophilicity of its surface are higher than that of B-PCE. A reason for the different drug release rates for PCE and B-PCE is suggested.     

Amphiphilic polymers as pseudotemplates in the synthesis of metal sols

The effects of poly(ethylene glycol) and its amphiphilic polymers on the products of copper ion reduction in aqueous solutions are studied. Whereas coarse metal dispersions are formed in poly(ethylene glycol) solutions, stable sols of metal nanoparticles with diameters of 2 nm and above are produced in the presence of poly(ethylene glycol monolaurate) and poly(ethylene glycol monostearate). A poly(ethylene glycol)-poly(propylene glycol) block copolymer (Pluronic) also stabilizes copper nanoparticles; however, the interaction product of this copolymer with nanoparticles forms a precipitate. According to the electron microscopy data, sol particles comprise polymer micelles containing included copper nanoparticles.     

Synthesis of double hydrophilic graft copolymer containing poly(ethylene glycol) and poly(methacrylic acid) side chains via successive ATRP

A well‐defined double hydrophilic graft copolymer, with polyacrylate as backbone, hydrophilic poly(ethylene glycol) and poly(methacrylic acid) as side chains, was synthesized via successive atom transfer radical polymerization followed by the selective hydrolysis of poly(methoxymethyl methacrylate) side chains. The grafting‐through strategy was first used to prepare poly[poly(ethylene glycol) methyl ether acrylate] comb copolymer. The obtained comb copolymer was transformed into macroinitiator by reacting with lithium diisopropylamine and 2‐bromopropionyl chloride. Afterwards, grafting‐from route was employed for the synthesis of poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methoxymethyl methacrylate) amphiphilic graft copolymer. The molecular weight distribution of this amphiphilic graft copolymer was narrow. Poly(methoxymethyl methacrylate) side chains were connected to polyacrylate backbone through stable C? C bonds instead of ester connections. The final product, poly[poly(ethylene glycol) methyl ether acrylate]‐g‐poly(methacrylate acid), was obtained by selective hydrolysis of poly(methoxymethyl methacrylate) side chains under mild conditions without affecting the polyacrylate backbone. This double hydrophilic graft copolymer was found be stimuli‐responsive to pH and ionic strength. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4056–4069, 2008     

Polycaprolactone–poly(ethylene glycol) block copolymer,I: synthesis and degradability in vitro

A new type of biodegradable polymer material, poly(caprolactone)–poly(ethylene glycol) block copolymer (PCL-b-PEG), was synthesized by means of direct copolycondensation of ε-caprolactone with poly(ethylene glycol) in the presence of a Ti(OBu)₄ catalyst. The degradability of the polycaprolactone was improved by introducing a PEG component into it. The degradation of PCL-b-PEG copolymer increase with a decreasing crystallinity of the copolymer, and can be controlled by adjusting the component ratio of the copolymer.     

Synthesis of a triblock copolymer: Poly(ethylene glycol)‐poly(alkylene phosphate)‐poly(ethylene glycol) as a modifier of CaCO3 crystallization

Triblock copolymer poly(ethylene glycol)‐poly(alkylene phosphate)‐poly(ethylene glycol) was prepared by first reacting hexamethylene glycol with dimethyl‐H‐phosphonate at conditions of transesterification and then replacing the CH₃OP(O)(H)O‐… end‐groups by monomethyl ether of poly(ethylene glycol). The course of reaction was studied by ³¹P NMR indicating complete conversion. After oxidation the poly(alkylene H‐phosphonate was converted into the final triblock polyphosphate. This triblock copolymer was used as a modifier of CaCO₃ crystallization. Unusual semi open empty spheres resulted, composed of small crystallites of the size (diameter) equal to 40–90 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 650–657, 2005     

Synthesis and Characterization of Poly(Lactic Acid) – Poly(Ethylene Glycol) Copolymer with Boc-Glycine End Groups in Medical Applications

Chemistry of Natural Compounds - Poly(lactic acid)-poly(ethylene glycol) with Boc-glycine linked copolymer was synthesized from lactic acid, poly(ethylene glycol), and Boc-glycine. The synthesized...     

四臂星形嵌段共聚物s-PDLLA-b-PEG的合成

季戊四醇与D,L-丙交酯开环聚合制得末端为羟基的四臂星形聚乳酸(s-PDLLA);s-PDLLA与羧基封端的聚乙二醇单甲醚(CT-mPEG)完成酯化反应,合成了以季戊四醇为核,以聚乳酸为内部嵌段、聚乙二醇为外部嵌段的四臂星形聚(D,L-乳酸)-聚乙二醇嵌段共聚物(s-PDLLA-b-PEG),其结构经1H NMR,IR和GPC表征。     

Nontoxic block copolymer nanospheres: design and characterization

Biodegradable polymers capable of self-assembly into hollow nanospheres of less than 100 nm have significant potential for biotechnology applications such as drug delivery and gene therapy. Here we describe the synthesis of a novel ABA-type triblock copolymer made from a hydrophobic tyrosine-derived core and two hydrophilic poly(ethylene glycol) end groups (poly(ethylene glycol)-block-oligo(desaminotyrosyltyrosine octyl ester suberate)-block-poly(ethylene glycol)). We describe the self-assembly of this triblock copolymer and characterize its particles as 100 nm size vesicular nanospheres. The vesicular nature of these particles was determined by light scattering and electron microscopy. The nanospheres did not exhibit any short-term cytotoxicity toward UMR-106 cells at a concentration up to 2 mg/mL.     

Poly(ε‐caprolactone)‐Based Organogels and Hydrogels with Poly(ethylene glycol) Cross‐Linkings

Summary: The reaction of triphosgene with poly(ethylene glycol) yielded poly(ethylene glycol) dichloroformate. This difunctional cross‐linker was allowed to react with poly(ε‐caprolactone) bearing carbanionic sites obtained by activation with lithium diisopropylamide. The reaction resulted in the cross‐linking of poly(ε‐caprolactone) chains by poly(ethylene glycol) segments, giving copolymer networks that gel in both organic and aqueous media.

Schematic of the PCL‐g‐PEG copolymers synthesized here.     

Novel synthesis of biodegradable poly(lactide-co-ethylene glycol) block copolymers

Biodegradable and amphiphilic diblock copolymers [polylactide-block-poly(ethylene glycol)] and triblock copolymers [polylactide-block-poly(ethylene glycol)-block-polylactide] were synthesized by the anionic ring-opening polymerization of lactides in the presence of poly(ethylene glycol) methyl ether or poly(ethylene glycol) and potassium hexamethyldisilazide as a catalyst. The polymerization in toluene at room temperature was very fast, yielding copolymers of controlled molecular weights and tailored molecular architectures. The chemical structure of the copolymers was investigated with ¹H and ¹³C NMR. The formation of block copolymers was confirmed by ¹³C NMR and differential scanning calorimetry investigations. The monomodal profile of the molecular weight distribution by gel permeation chromatography provided further evidence of block copolymer formation as well as the absence of cyclic species. Additional confirmation of the block copolymers was obtained by the substitution of 2-butanol for poly(ethylene glycol); butyl groups were clearly identified by ¹H NMR as polymer chain end groups. The effects of the copolymer composition and lactide stereochemistry on the copolymer properties were examined. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2235–2245, 2007     

磷酸钙骨水泥/聚肽共聚物生物复合材料力学性能及微观结构

磷酸钙骨水(Calcium Phosphate Cement,CPC)是一种新型的人工骨材料,可用于人体骨缺损的修复,具有良好的生物相容性、骨传导性和骨替代性．然而,磷酸钙骨水泥的抗压强度较低,脆性较大,限制了其应用,因而提高抗压强度和减小其脆性成为CPC研究领域的一个重要课题．目前,普遍采用添加纤维的方法来提高CPC材料的抗压强度和韧性．然而大多数的纤维是非降解性的．     

PPEGMEA-g-PDEAEMA全亲水接枝共聚物的合成及其 包埋甲氨喋呤体外控释的研究

以聚乙二醇丙烯酸酯(PEGMEA)为起始原料, 将原子转移自由基聚合(ATRP)技术和从主干接枝(grafting-from)策略相结合, 合成了结构规整的聚甲基醚聚乙二醇丙烯酸酯-g-聚(N,N’-二乙基胺乙基甲基丙烯酸酯) (PPEGMEA-g- PDEAEMA)接枝共聚物. 这种接枝共聚物通过静电作用形成胶束包埋甲氨喋呤(MTX), 得到具有98.7%高包封率的药物载体, 体外药物释放得到很好的控制.     

Novel synthesis of biodegradable amphiphilic linear and star block copolymers based on poly(ε‐caprolactone) and poly(ethylene glycol)

Biodegradable, amphiphilic, diblock poly(ε‐caprolactone)‐block‐poly(ethylene glycol) (PCL‐b‐PEG), triblock poly(ε‐caprolactone)‐block‐poly(ethylene glycol)‐block‐poly(ε‐caprolactone) (PCL‐b‐PEG‐b‐PCL), and star shaped copolymers were synthesized by ring opening polymerization of ε‐caprolactone in the presence of poly(ethylene glycol) methyl ether or poly(ethylene glycol) or star poly(ethylene glycol) and potassium hexamethyldisilazide as a catalyst. Polymerizations were carried out in toluene at room temperature to yield monomodal polymers of controlled molecular weight. The chemical structure of the copolymers was investigated by ¹H and ¹³C NMR. The formation of block copolymers was confirmed by ¹³C NMR and DSC investigations. The effects of copolymer composition and molecular structure on the physical properties were investigated by GPC and DSC. For the same PCL chain length, the materials obtained in the case of linear copolymers are viscous whereas in the case of star copolymer solid materials are obtained with low T_g and T_m temperatures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3975–3985, 2007     

生物降解性聚己内酯-聚醚嵌段共聚物的合成及表征

生物降解性高分子具有在生理条件下可以自行降解、代谢,使之被机体吸收或被排泄的特点,因此可以免除在进入体内后需再经手术方法取出的麻烦。由此,生物降解性高分子在作为药物释放体系的药物载体和在医疗上作为外科手术组织修饰材料等方面具有十分广阔的应用前景,并且成为当前生物医用高分子领域的一个重要的研究课题。     

Microporous structure and drug release kinetics of polymeric nanoparticles

The aim of the present study was to characterize pegylated nanoparticles (NPs) for their microporosity and study the effect of microporosity on drug release kinetics. Blank and drug-loaded NPs were prepared from three different pegylated polymers, namely, poly(ethylene glycol)1%-graft-poly(D,L)-lactide, poly(ethylene glycol)5%-graft-poly(D,L)-lactide, and the multiblock copolymer (poly(D,L)-lactide-block-poly(ethylene glycol)-block-poly(D,L)-lactide)n. These NPs were characterized for their microporosity using nitrogen adsorption isotherms. NPs of the multiblock copolymer showed the least microporosity and Brunauer-Emmett-Teller (BET) surface area, and that of PEG1%-g-PLA showed the maximum. Based on these results, the structural organization of poly(D,L)-lactide (PLA) and poly(ethylene glycol) (PEG) chains inside the NPs was proposed and was validated with differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS) surface analysis. An in vitro drug release study revealed that PEG1%-g-PLA NPs exhibited slower release despite their higher surface area and microporosity. This was attributed to the presence of increased microporosity forming tortuous internal structures, thereby hindering drug diffusion from the matrix. Thus, it was concluded that the microporous structure of NPs, which is affected by the molecular architecture of polymers, determines the release rate of the encapsulated drug.     

生物降解性聚己内酯-聚醚嵌段共聚物的合成及表征

A new biodegradable Poly (e-caprolactone)-Poly (ethylene glycol) block copolymer (PCL-b-PEG) has been synthesized by co-polycondensation reaction of e-caprolactone (e-CL) and poly (ethylene glycol) (PEG) in the presence of Ti(OBu)4 catalyst. The composition,hy-drophilicity and crystallinity of the copolymer can be controlled by changing the feeding dose of reaction system. The degradation rate of the PCL-b-PEG copolymer is improved by introducing the PEG segment, and the more the PEG content in the copolymers,the faster the degradation rate of the copolymer.     

Synthesis and characterization of a novel macromolecular surface modifier for polyethylene

A new macromolecular surface modifier, a copolymer of lauryl methacrylate (LMA) and poly(ethylene glycol) methyl methacrylate (PEGMA), was synthesized through free radical polymerization. The copolymer was characterized by nuclear magnetic resonance spectrum (1H-NMR) and thermogravimetric analysis (TGA). The copolymer was used to blend with polyethylene. The binary blends have been characterized by attenuated total reflection/Fourier transform infrared (ATR-FTIR), contact-angle measurements (CDA) and scanning electron microscopy (SEM). The results indicated that poly(ethylene glycol) methyl methacrylate-co-lauryl methacrylate (PEGMA-co-LMA) could diffuse preferably onto the surface of the polyethylene (PE) film, and thus can be used as an efficient surface modifier for PE.     

Pegylated single-walled carbon nanotubes with gelable block copolymers

Functional amphiphilic block copolymer poly（ethylene glycol）-block-poly[（3-（triethoxysilyl）propyl methacrylate）-co -（1-pyrene-methyl） methacrylate],PEG₁₁₃-b-P(TEPM₂₆-co-PyMMA₄),was synthesized via atom transfer radical polymerization（ATRP） initiated by monomethoxy capped poly（ethylene glycol） bromoisobutyratc.This polymer exhibited strong ability to disperse and exfoliate single-walled carbon nanotubes（SWNTs） in different solvents due to the adhesion of pyrene units to surface of SWNTs.In aqueous solution,the PTEPM segments that were located on the nanotube surfaces with the pyrene units could be gelated and,as a result,the silica oxide networks with PEG coronas were formed on the surface of nanotubes,which ensured the composites with a good dispersibility and stability.Furthermore,functional silane coupling agents,3-mercaptopropyltrimethoxysilane and 3-aminopropyltriethoxysilanc,were introduced during dispersion of SWNTs using the block copolymers.They were co-gelated with PTEPM segments,and the-SH and-NH₂ functionalities were introduced into the silica oxide coats respectively.