Synthesis and characterization of an environmentally friendly PHBV/PEG copolymer network as a phase change material

Novel environmentally friendly poly(hydroxybutyrate-co-hydroxyvalerate) and poly(ethylene glycol) (PHBV/PEG) copolymer networks were synthesized through free-radical solution polymerization with PHBV diacrylate (PHBVDA) and polyethylene glycol diacrylate (PEGDA) as macromers. The molecular structure of PHBV/PEG copolymer network was characterized by Fourier transform infrared (FT-IR) and ¹H nuclear magnetic resonance (¹H NMR). The morphology of the PHBV/PEG copolymer network was characterized by polarization optical microscopy. Thermal energy storage properties, thermal reliability and thermal stability were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis. The results indicated that the PHBV/PEG copolymer network hindered the growth of PEG crystalline segments or PHBV segments. PHBV/PEG copolymer network had a higher latent heat enthalpy, which didn’t reduce with the components of PHBV increased. Moreover, PHBV/PEG copolymer network still had good thermal stability even at 300 °C. These results suggested that such environmentally friendly copolymer network would have wide applications in phase change energy storage materials.     

The mobility of PEG chains versus micellar stability towards the formation of PE‐b‐PEG nanohybrid shish‐kebab on carbon nanotubes

A comparative study of the effect of copolymer composition on nanohybrid shish‐kebab (NHSK) architecture on carbon nanotubes (CNTs) is presented. A semi‐crystalline amphiphilic di‐block copolymer, polyethylene‐b‐polyethylene glycol (PE‐b‐PEG) was used in this study. Copolymer composition was varied on the basis of the molecular weight of individual copolymers and the ratio between PE and PEG. NHSK structure was characterized using a combination of scanning and transmission electron microscopy. The mobility of PEG, which is determined by its chain length was found to have a significant impact on the periodic decoration of the copolymer on CNTs. With higher chain length or molecular weight, PEG chains provided better stability to micelles formed by the copolymer. Further, PEG assisted micellar stability to create a foundation for PE chains to interact and orient along the tube axis of CNTs as a function of the copolymer composition. It was found that the stability of NHSK architecture can also be changed over time at the same crystallization temperature. This work offers novel and fundamental insights towards the mobility of PEG in the copolymer and its disk‐shaped crystal's formation and micellar stability during crystallization with CNTs. This study provides a better understanding of a mechanically tunable NHSK where the architecture of copolymer crystals can be modified by adjusting the molecular weight of PEG.     

聚乙二醇改性聚乳酸的研究

将丙交酯（ＤＬ ＬＡ）与聚乙二醇（ＰＥＧ）共聚得到了一系列高分子量的共聚物．用ＩＲ、１Ｈ ＮＭＲ和ＤＭＡ对它的结构和粘弹性进行了表征，并测定了其力学性能，同时对材料在加工过程中特征粘度的变化也进行了研究．结果表明，ＰＥＧ与ＬＡ的共聚物是一种三嵌段结构ＨＯ ＰＬＡ ＰＥＧ ＰＬＡ ＯＨ．当ＰＥＧ含量增加时，强度下降，伸长率增加，共聚物逐渐由脆性向韧性转变，因此用ＰＥＧ改性的ＰＬＡ是一种综合性能可调控的生物降解材料     

LLDPE/SMA共混膜表面接枝PEG的研究

聚乙烯综合性能优良且价格低廉,但由于较低的表面能和惰性化学结构,其着色性、生物相容性及制品表面涂饰性能差,与各种涂饰剂的粘结强度很低,限制了其用途的拓展,须进行表面改性.聚乙烯制品的表面改性方法已有不少研究报道[1~4],相对而言,采用添加表面改性剂的方法在工艺上仍最     

Influence of Different Types of Block Copolymers on the Secondary Structure and Stability of the Staphylolytic Lysk Enzyme

A branched block copolymer of polyethyleneimine and polyethylene glycol (PEI–PEG) and a linear block copolymer of polylysine and polyethylene glycol (PLL–PEG) form complexes with the staphylolytic LysK enzyme. The complexation between LysK and cationic block-copolymers results in a 1.5–2.0-fold increase in the lytic activity of LysK and a 2–20-fold increase in its half-life. The stabilizing effects of the block copolymers depend on the temperature, the NaCl concentration, and the polymer/enzyme ratio. Being an effective stabilizer, linear PLL–PEG provides an increase in the LysK stability suitable for biomedical materials (LysK maintains 100% of its activity after four months at 4°C).     

Composition analysis of poly(ethylene glycol)-poly(L-lactide) diblock copolymer studied by two-dimensional column chromatography

We used two-dimensional column chromatography to analyze the composition of a sample of presumably a diblock copolymer of poly(ethylene glycol) (PEG) and poly(L-lactide) synthesized from monomethoxy-terminated PEG. The first dimension of the separation is phase fluctuation chromatography to prepare fractions that contain various components of the copolymer in different ratios. The second dimension is size-exclusion chromatography, NMR, and HPLC at the critical condition of PEG. The PEG initiator has small amounts of diol-terminated dimeric components. We found that the copolymer sample contains a triblock copolymer and low-molecular-mass components in addition to the main part of the diblock copolymer. The SEC chromatograms show that the main part consists of two components with distinct peak lengths for the PLLA block. The low-molecular-mass components have a broad distribution in chemical composition. Phase fluctuation chromatography enriched the triblock copolymer and the diblock copolymer with the longer PLLA block in early fractions when the column was packed with carboxymethyl-modified porous silica. When the porous medium was PLLA-grafted silica, size exclusion dominated, but the low-molecular-mass components were separated according to their chemical composition.     

Supramolecular micellization and pH‐inducible gelation of a hydrophilic block copolymer by block‐specific threading of α‐cyclodextrin

A poly(ethylene glycol)‐b‐poly(L ‐lysine) diblock copolymer (PEG‐b‐PLL) was synthesized. Micellization of this hydrophilic copolymer due to the block‐specific threading of α‐cyclodextrin (α‐CD) molecules onto the polyethylene glycol (PEG) block yielded supramolecular‐structured nanoparticles, which undergoes pH‐inducible gelation in aqueous media. The pH‐inducible gelation of supramolecular micelle in water appeared to be completely reversible upon pH changes. The synergetic effect of selective complexation between PEG block and α‐CD and the pH‐inducible hydrophobic interaction between PLL blocks at pH 10 was believed to be the driving force for the formation of the supramolecular hydrogel. ¹H NMR and wide angle X‐ray diffraction (WAXD) were employed to confirm the inclusion complexation between α‐CD and PEG block. Meanwhile, the morphology of the micellized nanoparticles was investigated by transmission electron microscopy (TEM). The thermal stability of inclusion complexes (ICs) was investigated and the rheologic experiment was conducted to reveal the micelle‐gel transition. Such pH‐induced reversible micelle‐gel transition of the supramolecular aggregates may find applications in several fields, for example as advanced biomedical material possessing stimulus‐responsiveness. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 782–790, 2008     

Solid polymer electrolytes III: Preparation,characterization, and ionic conductivity of new gelled polymer electrolytes based on segmented,perfluoropolyether‐modified polyurethane

New segmented polyurethanes with perfluoropolyether (PFPE) and poly(ethylene oxide) blocks were synthesized from a fluorinated macrodiol mixed with poly(ethylene glycol) (PEG) in different ratios as a soft segment, 2,4‐toluene diisocyanate as a hard segment, and ethylene glycol as a chain extender. Fourier transform infrared, NMR, and thermal analysis [differential scanning calorimetry and thermogravimetric analysis (TGA)] were used to characterize the structures of these copolymers. The copolymer films were immersed in a liquid electrolyte (1 M LiClO₄/propylene carbonate) to form gel‐type electrolytes. The ionic conductivities of these polymer electrolytes were investigated through changes in the copolymer composition and content of the liquid electrolyte. The relative molar ratio of PFPE and PEG in the copolymer played an important role in the conductivity and the capacity to retain the liquid electrolyte solution. The copolymer with a 50/50 PFPE/PEG ratio, having the lowest decomposition temperature shown by TGA, exhibited the highest ionic conductivity and lowest activation energy for ion transportation. The conductivities of these systems were about 10^?3 S cm^?1 at room temperature and 10^?2 S cm^?1 at 70 °C; the films immersed in the liquid electrolyte with an increase of 70 wt % were homogenous with good mechanical properties. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 486–495, 2002; DOI 10.1002/pola.10119     

Catalytic Oxidative Deformylation of Polyethylene Glycols with the Participation of Molecular Oxygen

The kinetics of oxidation of diethylene glycol, triethylene glycol, and polyethylene glycols (PEGs) with molecular weights ranging from 400 to 2000 in the presence of Cu(II) ions and bases was studied. It was found that ethylene glycols can be oxidized by molecular oxygen in anhydrous media in a temperature range of 30–60°C at anomalouosly high rates which are higher than the rates of chain-radical PEG autoxidation by several orders of magnitude. Only terminal hydroxyl groups were subjected to oxidation. The reaction occurs with the cleavage of a C–C bond and results in the formation of formic acid and a PEG with the number of –(CH₂CH₂O)– groups lower than that in the parent compound by unity. The rate and selectivity of PEG oxidation were found to strongly depend on the molecular weight of the polymer; from diethylene glycol to PEG 2000, the specific rate of oxidation increased by a factor of 60 in terms of terminal hydroxyl groups. An oxidation mechanism was suggested, which involves the formation of ternary complexes [Cu²⁺···A^–···O₂], which undergo further degradation by a many-electron concerted mechanism to form formic acid and, probably, an unstable hemiacetal {RO–CH₂OH}. The rapid oxidative degradation of the latter leads to the formation of PEG with a lower molecular weight.     

Synthesis and Application of Ruthenium(II) Alkenyl Complexes with Perylene Fluorophores for the Detection of Toxic Vapours and Gases

A series of new ruthenium(II) vinyl complexes has been prepared incorporating perylenemonoimide (PMI) units. This fluorogenic moiety was functionalised with terminal alkyne or pyridyl groups, allowing attachment to the metal either as a vinyl ligand or through the pyridyl nitrogen. The inherent low solubility of the perylene compounds was improved through the design of poly-PEGylated (PEG=polyethylene glycol) units bearing a terminal alkyne or a pyridyl group. By absorbing the compounds on silica, vapours and gases could be detected in the solid state. The reaction of the complexes [Ru(CH=CH-Per^Im)Cl(CO)(py-3PEG)(PPh₃)₂] and [Ru(CH=CH-3PEG)Cl(CO)(py-Per^Im)(PPh₃)₂] with carbon monoxide, isonitrile or cyanide was found to result in modulation of the fluorescence behaviour. The complexes were observed to display solvatochromic effects and the interaction of the complexes with a wide range of other species was also studied. The study suggests that such complexes have potential for the detection of gases or vapours that are toxic to humans.     

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.     

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．     

全氟甲基乙烯基醚和其它含氟单体乳液共聚合的竞聚率测定

分别通过气相色谱法测定了全氟甲基乙烯基醚 (PMVE)与偏氟乙烯 (VDF)以及PMVE与四氟乙烯(TFE)二元乳液共聚反应中的气相单体组成和共聚物组成 ,然后用非线性回归法 (RREVM )计算得TFE PMVE及VDF PMVE乳液共聚合反应的表观竞聚率分别为γTFE =3 89和γPMVE =0 0 5以及γVDF =1 0 6和γPMVE =0 11.结合已经测定的TFE VDF二元乳液共聚的表观竞聚率 ,计算了由VDF TFE PMVE三元乳液共聚合反应合成的共聚物组成 ,后者与由1 9F NMR实测的共聚物组成吻合     

New solid polymer electrolytes based on polyester diacrylate for lithium power sources

New solid polymer electrolytes are developed for a lithium power source used at the temperatures up to 100°C. Polyester diacrylate (PEDA) based on oligohydroxyethylacrylate and its block copolymers with polyethylene glycol were offered for polymer matrix formation. The salt used was LiClO₄. The ionic conductivity of electrolytes was measured in the range of 20 to 100°C using the electrochemical impedance method. It is shown that the maximum conductivity in the whole temperature range is characteristic of the electrolyte based on the PEDA copolymer and polyethylene glycol condensation product (2.8 × 10^?6 S cm^?1 at 20°C, 1.8 × 10^?4 S cm^?1 at 95°C).     

Composition equation for matrix copolymerization

A mechanism of matrix copolymerization in which a monomer (or macroradical) is complexed by matrix was considered. For this case a composition equation was formulated. It was shown that in general case reactivity ratios are dependent on the matrix concentration. The influence of the critical length of a complexed radical on the process of copolymerization is also discussed. A series of copolymerizations of methacrylic acid and styrene were carried out using various compositions of initial monomer mixtures. The process was performed in benzene in the presence of poly(ethylene glycol) as a matrix. The copolymerization were carried out at various ratios of the monomer being complexed (methacrylic acid) to the matrix. Compositions of the complexes prepared were determined by the NMR method. Reactivity coefficients for both monomers were found and the results are discussed on the basis of the derived equation.     

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。     

Extraction of europium and cerium into nitrobenzene using synergistic mixture of hydrogen dicarbollylcobaltate and polyethylene glycol PEG 600

Solvent extraction of microamounts of europium and cerium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B⁻) in the presence of polyethylene glycol PEG 600 (L) has been investigated. The equilibrium data have been explained assuming that the complexes HL⁺, H₂L²⁺ and ML³⁺ (M³⁺ = Eu³⁺, Ce³⁺; L = PEG 600) are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. It was found that the stability constants of the EuL³⁺ and CeL³⁺ cationic complex species (L = PEG 600) in water-saturated nitrobenzene are the same.     

Kinetic Studies of Acylation of Polyethylene Glycol Hydroxyl Groups

The reactivity of polyethylene glycol (PEG) hydroxyl groups was studied by acylation with benzoyl bromide in the presence of a catalyst (tributylamine). The reaction rate constants were calculated for all forms of H-complexes in PEG solutions in CCl₄ and dioxane.     

聚对苯二甲酸乙二醇酯/聚乙二醇醚插层嵌段共聚物的结晶性能

合成了不同用量、不同分子量的聚乙二醇醚(PEG)或聚丁二醇醚(PTMC)与聚对苯二甲酸乙二醇酯(PET)/蒙脱土(MMT)的嵌段共聚物。研究了MMT在共聚物中的分散状态及PEG或PTMG对PET/MMT插层聚合物结晶性能的影响。结果表明,MMT在共聚物中以纳米尺寸分散;加入PEG或PTMG增强了聚酯链段的柔顺性,使共聚物熔体降温过程的结晶温度提高,冷结晶温度降低,即插层嵌段共聚物的结晶速率提高;在合成的共聚物中,分子量为2000,用量为DMT的6%的PEG对插层共聚物结晶速率的促进作用最大     

Synthesis and characterization of aba-type block copolymer of poly(ϵ-caproplactone) with poly(ethylene glycol), by mean of activation end groups

Poly(?-caprolactone)-b-poly(ethylene glycol)-b-poly(?-caprolactone) (PCL-b-PEG-b-PCL) triblock copolymer were synthesized by mean anionic activation of the hydroxyl end groups of poly(ethylene glycol) in presence of diphenylmethylsodium. Copolymers were characterized by SEC, FT-IR and ¹H-NMR spectroscopy, TGA and DSC. Size exclusion chromatographic analysis of obtained copolymers indicated incorporation of CL monomer into PEG without formation of PCL homopolymer. Characterization by FT-IR and ¹H NMR spectroscopy of the resulting polymeric products, with respect to their structure, end-groups and composition, showed that they are best described as ester-ether-ester triblock copolymers, whose compositions can be adjusted changing the feeding molar ratio of PEG to CL. The thermal stability of triblock copolymers was less that PEG precursor, but higher that PCL homopolymer. Analysis by mean DSC showed that all copolymers were semi-crystalline and their thermal behavior depending on their composition.