PEG Weight Fraction Research Articles

Cellulose Acetate/Polyethylene Glycol Composite Beads for Efficient Removal of Methylene Blue

The development of eco-friendly and biodegradable adsorbent with excellent adsorption performance is of great importance for the efficient dye removal in wastewater. Herein, an efficient and biodegradable composite adsorbent bead was fabricated from cellulose acetate (CA) modified with low molecular weight polyethylene glycol 200 (PEG200) for the adsorptive removal of methylene blue dye (MB) from aqueous solution. The weight fraction of PEG was varied to investigate the effect of material bead composition on the morphology, molecular structure, crystal phases, thermal stability, mechanical properties, and adsorption performance of the composite beads. Batch adsorption was carried out at various times to estimate the time at equilibrium adsorption capacity and kinetic model. Various operating conditions such as pH, initial MB concentration, and adsorbent dosage in experiment were also executed to examine the adsorption performance of this system. The result showed that all beads have porous structure and the pore size increase after the addition of PEG200. The adsorption capacity and % MB removal generally showed an improvement with the rise of PEG content. The batch adsorption experiments demonstrated that the best % removal and adsorption capacity of MB were 93.35 % and 28.005 mg/g, respectively, that was obtained by composite CA/PEG200 (80/20) bead at pH of 11, initial MB concentration of 30 mg/L, and bead dosage of 1 g/L. The adsorption kinetic fitted well to Elovich-kinetic model with average R2 of 0.844. Overall, this work offers new finding into the development of effective, environmentally friendly, and inexpensive cellulose-based adsorbents for wastewater remediation.

Reprocessable, biodegradable polyester-based solid-solid phase change materials networks from dynamic ionic crosslinking with high latent heat capability

Thermosetting polyethylene (PEG)-based solid-solid phase change materials networks (PCMNs) have high latent leat and form stability from the covalent crosslinking, yet they remain a great challenge in reprocessing and recycling of PCMNs without compromising a high latent heat above 100 J/g. Herein, the polyester-based solid-solid PCMNs with PEG as phase change component were synthesized via ionic crosslinking between the linear multiple carboxyl-functionalized phase change materials (CPCMs) polyester and zinc cations. The CPCMs were synthesized via polyesterification reaction between pyromellitic dianhydride (PMDA) and diol containing PEG and ethylene glycol, meanwhile forming multiple carboxyl along molecular chains. The dynamic ionic bonds and hydrolysable ester bonds endowed PCMNs with the reprocessability and biodegradability, respectively. PCMNs had the ΔH = 120 J/g with PEG weight fraction of ∼0.91 and concentration of carboxyl of ∼0.26 mmol/g. Also, PCMNs had good phase change ability, thermal stability and thermal reliability before and after thermal cycling and reprocessing. The robust approach enabled the combination of the reprocessing ability and high latent heat of PCMNs by ionic crosslinking.

Bio-based poly(butylene 2,5-furandicarboxylate)-b-poly(ethylene glycol) copolymers with adjustable degradation rate and mechanical properties: Synthesis and characterization

Bio-based poly(butylene furandicarboxylate)-b-poly(ethylene glycol) copolymers are successfully synthesized through transesterification and melt polycondensation. The resulted polymers are characterized in terms of structural, thermal and mechanical properties. In addition, for the first time relevant hydrolytic degradation studies for the copolymers applications are systematically conducted in neutral and alkaline conditions. The PEG weight fraction ranges from 10% to 60%, as determined by 1H NMR. Isothermal crystallization tests show that the copolymers own faster crystallization rate than that of PBF, with melting temperature higher than 120 °C. Water contact angle and water uptake characterizations show that the introduction of increasing amounts of PEG improves the hydrophilic character of the copolymers. Tensile tests clearly indicate that elongation at break drastically increase with PEG content, up to 5 times compared to PBF. From the Notched Izod impact tests, most samples are unbroken in the impact testing, showing excellent impact toughness. It is surprising to find that after water uptake, the PBF-PEGs still have acceptable mechanical properties. The weight loss during hydrolytic degradation is significant after 5 weeks for most of copolymers. With fast hydrolytic degradation rate and good mechanical properties, these copolymers own potential applications in areas like biomedical industry.

Using silicagel industrial wastes to synthesize polyethylene glycol/silica-hydroxyl form-stable phase change materials for thermal energy storage applications

Polyethylene glycol form-stable phase change materials (PEG FSPCMs) have received much attention in recent years for thermal energy storage applications due to their remarkable thermal properties. However, the conventional synthesis of PEG FSPCMs usually employed chemical grade regents as starting materials, which is unlikely suitable for large-scale industrial preparation of PCMs. In the present work, silicagel industrial wastes were employed as starting materials for the first time to synthesize a polyethylene glycol/silica-hydroxyl compound (PEG/SHC) form-stable phase change material using a facile sol-gel method. The morphology and chemical compatibility were characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The thermal energy storage performance was evaluated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermal constants analysis, respectively. The results indicated that the PEG was encapsulated in the SHC matrix through a physical interaction, and the weight fraction of PEG in the FSPCM could be as high as 80% with no significant leaking liquid observed. The thermal energy storage capacity in this FSPCM was found to be (59.38–132.4) J/g and (63.56–133.4) J/g in the melting and crystallization process, respectively, as the loaded PEG weight fraction ranging from 50% to 80%. The thermal conductivity of the FSPCM enhanced by the SHC matrix was determined to be as high as 30% compared with that of the pure PEG. Additionally, the FSPCM synthesized in this method could maintain a stable thermal property during the heating/cooling cycles. On the basis of these results, it was demonstrated that the sol-gel method developed in this work could not only obtain PEG based FSPCMs with good performance for thermal energy storage, but also propose an effective way of producing economic benefits by reusing silicagel industrial wastes.

Induction of Secondary Structure through Micellization of an Oppositely Charged Pair of Homochiral Block- and Homopolypeptides in an Aqueous Medium.

Polyion complex (PIC) formation is an attractive method for obtaining molecular assemblies owing to their facile fabrication process in aqueous media, but more insights are required in order to control the higher-dimensional structures of polypeptide-based PICs. Herein, the PIC formation behavior of oppositely charged homochiral polypeptides, poly-L-lysine and poly(ethylene glycol)-b-poly(L-glutamate) (PEG-PLG), and their secondary structures are carefully studied in water. PIC formation takes place in a polymer concentration-dependent manner, and clear β-sheet formation is observed at polymer concentrations ≥0.3 mg mL(-1). The results also confirm that multimolecular aggregation is a prerequisite for β-sheet formation, which indicates that the inner hydrophobic environment of PICs is favorable for β-sheet formation. Furthermore, the PEG weight fraction, stereoregularity of the polypeptide, and ionic strength of the solutions are found to be key factors for generating a secondary structure, presumably because these factors can contribute to the tuning of the inner environment of PICs. This method of producing water-soluble nanoassemblies from oppositely charged polypeptides may expedite self-assembly studies in biological systems and be incorporated into various molecular systems to exploit protein-mimicking features.

Tough stimuli-responsive supramolecular hydrogels with hydrogen-bonding network junctions.

Hydrogels were prepared with physical cross-links comprising 2-ureido-4[1H]-pyrimidinone (UPy) hydrogen-bonding units within the backbone of segmented amphiphilic macromolecules having hydrophilic poly(ethylene glycol) (PEG). The bulk materials adopt nanoscopic physical cross-links composed of UPy-UPy dimers embedded in segregated hydrophobic domains dispersed within the PEG matrix as comfirmed by cryo-electron microscopy. The amphiphilic network was swollen with high weight fractions of water (w(H2O) ≈ 0.8) owing to the high PEG weight fraction within the pristine polymers (w(PEG) ≈ 0.9). Two different PEG chain lengths were investigated and illustrate the corresponding consequences of cross-link density on mechanical properties. The resulting hydrogels exhibited high strength and resilience upon deformation, consistent with a microphase separated network, in which the UPy-UPy interactions were adequately shielded within hydrophobic nanoscale pockets that maintain the network despite extensive water content. The cumulative result is a series of tough hydrogels with tunable mechanical properties and tractable synthetic preparation and processing. Furthermore, the melting transition of PEG in the dry polymer was shown to be an effective stimulus for shape memory behavior.

Morphology Control in Water of Polyion Complex Nanoarchitectures of Double-Hydrophilic Charged Block Copolymers through Composition Tuning and Thermal Treatment

Polyion complexes (PICs) are attractive as eco-friendly materials, because they offer simple and fast preparation methods to exert various functionalities in aqueous medium. However, control of nanoarchitectures in PIC materials has not been fully realized, except for the case of micelles and unilamellar vesicles formed from block ionomers. Here, the procedure to control PIC nanoarchitectures with various morphologies was established for the first time by careful tuning in the composition of PICs made from PEG-based block-ionomers with a varying amount of homoionomers as additive to modulate the PEG weight fraction (fPEG) in the obtained PICs. Accordingly, the variation in fPEG from 12.1% to 6.5% induced vigorous transition in the microphase separated structures of PICs basically from micelle to lamella via cylindrical network. Notably, uniformed lamella with alternative layers of PEG and PIC domains was found at elevated temperature (70 °C), which, by lowering temperature, reversibly transformed to cylindrical PIC network apparently with connected aqueous channel in mesoscopic scale.

Structural factors directing nanosized polyion complex vesicles (Nano-PICsomes) to form a pair of block aniomer/homo catiomers: studies on the aniomer segment length and the catiomer side-chain structure

The aim of this study is to establish the factors that affect the formation of polyion complex (PIC) vesicles. The effects of anionic segment length of PEG-PAspy, and chemical structure of the side chains of Homo-P(Asp-Cn)x on the properties of PICs were carefully examined. It was found that PEG weight fraction (fPEG) has a significant role in determining the PIC morphologies as PICs with fPEG 10%. In addition, Homo-P(Asp-Cn)x containing five and six carbon atoms on the aliphatic spacers in their side chains facilitated the formation of Nano-PICsomes (compared with the shorter ones). These findings shed new light on how to control the structure and properties of PIC assemblies for diverse material applications.

Development and Evaluation of PEG-Lithium Citrate Salt Based Aqueous Two Phase System and Its Application in Partitioning of Proteins from Fish Industry Effluent

A aqueous two phase system (ATPS) comprising of PEG (Average mol. Wt: 4000, 6000, 8000) – lithium citrate salt-water systems were studied. The basic studies like binodal curve data generation and equilibrium studies were carried out. Furthermore, the binodal model and Othmer-Tobias and Bancroft models for phase equilibria were used for reproducing the experimental binodal data and phase equilibrium composition data, respectively. Good agreement was obtained with the experimental binodal data and tie line data with the models. The effective excluded volume values were obtained from the binodal model for the present ATPS. The tie line length was determined through the phase equilibrium composition data. This system was used to partition crude proteins of the fish industry effluent. The effects of PEG and salt weight fraction in terms of tie line length and effective excluded volume on partitioning coefficient of crude protein were studied in detail. From the results it was observed that, the crude proteins present in the fish effluent were partitioned in the PEG rich phase and the maximum partition coefficient of 7.82 was obtained. The results are discussed in the context of practical potential of this citrate based ATPS in separating crude proteins from fish industry effluent.

Shape-memory properties of magnetically active triple-shape nanocomposites based on a grafted polymer network with two crystallizable switching segments

Thermo-sensitive shape-memory polymers (SMP), which are capable of memorizing two or more different shapes, have generated significant research and technological interest. A triple-shape effect (TSE) of SMP can be activated e.g. by increasing the environmental temperature (Tenv), whereby two switching temperatures (Tsw) have to be exceeded to enable the subsequent shape changes from shape (A) to shape (B) and finally the original shape (C). In this work, we explored the thermally and magnetically initiated shape-memory properties of triple-shape nanocompos- ites with various compositions and particle contents using different shape-memory creation procedures (SMCP). The nanocomposites were prepared by the incorporation of magnetite nanoparticles into a multiphase polymer network matrix with grafted polymer network architecture containing crystallizable poly(ethylene glycol) (PEG) side chains and poly(!- caprolactone) (PCL) crosslinks named CLEGC. Excellent triple-shape properties were achieved for nanocomposites with high PEG weight fraction when two-step pro- gramming procedures were applied. In contrast, single-step programming resulted in dual-shape properties for all investi- gated materials as here the temporary shape (A) was predominantly fixed by PCL crystallites.

The ascorbyl palmitate–polyethyleneglycol 400–water system phase behavior

Ascorbyl palmitate (Asc16) in polyethyleneglycol 400 (PEG 400)–water mixtures at weight fractions (w/w) between 0.05 and 1.0 were studied by differential scanning calorimetry (DSC) and polarizing microscopy (PM) at different temperatures. The employed PEG 400–water proportions were: 0–25–50% and 75% of polymer. A complete phase diagram was determined for each PEG 400–water mixture.A cubic mesophase and two (probably three) lamellar mesophases were detected in different regions of the phase diagrams. The addition of PEG 400 to the Asc16–water system shifts the limits of the liquid crystalline domains to lower temperature and surfactant concentration. At weight fraction of PEG 400≥50%, the limits of the domain of existence of cubic mesophase shift to low surfactant concentration compared with water-rich systems. The hydrated crystals are Asc16.2·6H2O. If the proportion of water is lower than that value, a mixture of hydrated and anhydrous crystals appears. Heating these crystals produce waxy crystals having melted hydrocarbon bilayers retaining their crystalline structure because the polar bilayers are still rigid.

Monodispersed Polymeric Nanocapsules: Spontaneous Evolution and Morphology Transition from Reducible Hetero-PEG PICmicelles by Controlled Degradation

In this communication, a novel "self-templating" strategy was used to prepare uniform and biocompatible nanocapsules by the addition of a reduction agent (i.e., DTT) into a solution of highly monodispersed PICmicelles bearing a heterodetachable PEG corona. PEG chains were released from PICmicelle shells following disulfide reduction which leads a spontaneous and drastic morphology evolution from micelles to vesicles induced by the decrease of the PEG weight fraction. Formation of uniform nanocapsules with controllable capsule size was achieved by careful control of the micelle composition and molecular weight of homo-P[Asp(DET)].

Wloknotworcze kopoli(oksyetyleno-b-etylenotereftalany) o polepszonych wlasciwosciach optycznych

The conditions of synthesis of block copoly(oxyethylene-b-ethylene terephthalate)s (PEG-b-PET) with good optical parameters and designed for the production of hydrophilic fibers are presented. For polycondensation the catalysts: antimony trioxide (Sb2O3) and titanium tetraisopropoxide [Ti(OiPr)4] were used. The best optical properties of the polymers were achieved by using the mixture of Sb2O3/Ti(OiPr)4 catalysts. The system which thermally stabilize the PEG-b-PET copolymers was selected. It was stated that the melting temperature (Tm) of the copolymer was insignificantly lower than that of the PET homopolymer (...T=11K) when the content of PEG 4000 comonomer amounts 30 wt. %. When the weight fraction of PEG 4000 in the copolymer does not exceed 20 wt. % a cold crystallization is observed.

Preparation of superhydrophobic silica‐based films by using polyethylene glycol and tetraethoxysilane

AbstractPreparation of superhydrophobic silica‐based films via sol‐gel process by adding polyethylene glycol (PEG4000) in the silica sol precursor solution has been developed. The casting films were prepared by casting the above solution on the glass and adding poor solvent on it or not. Surface roughness of the films was obtained by removing polymer from the films at high temperature. Then, the hydrophobic group on the surfaces was obtained by reaction with hexamethyldisilazane (HMDS). Characteristic properties of the as‐prepared surface of the films were analyzed by contact angle measurement, scanning electron microscopy (SEM), atomic force microscope (AFM), Fourier transform infrared (FT‐IR) spectrophotometer, and X‐ray photoelectron spectrometer (XPS). The results showed that the contact angles of the films were varied with the PEG weight fraction of the films, the solvent for the PEG solution, the reaction temperature and time, and adding poor solvent (n‐hexane) or not. However, the surface roughness has been controlled by adjusting the experimental parameters during the early period. The contact angle of the film that prepared by spraying the poor solvent (n‐hexane) onto each coating layer for four times after casting process was greater than 150°. It was difficult to obtain superhydrophobic surface without adding n‐hexane onto any coating layer in this system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Miscibility of dextran and poly(ethylene glycol) in dilute aqueous solutions. II. Effect of temperature and composition

AbstractThe miscibility of dextran (Dx) with poly(ethylene glycol) (PEG) was investigated in dilute aqueous solutions by viscometry. Homopolymers of Dx and PEG and their blends with Dx/PEG ratios of 10/90, 25/75, 50/50, 75/25, and 90/10 were studied at 25, 30, 35, 40, and 45°C in bidistilled and deionized water. Starting with the classical Huggins equation, the results of the viscosity behavior of each parent polymer and their blends were interpreted in terms of miscibility parameters, Δk, Δb, α, β, ΔB, and μ. On the basis of the sign convention involved in these criteria, miscibility between Dx and PEG was found to increase with the weight fraction of PEG in the blend composition and temperature. The fourier transform infrared (FTIR) analysis is also used to investigate the miscibility of the polymer pairs. The existence of specific interactions between Dx and PEG was demonstrated by FTIR spectroscopy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4587–4594, 2006

Formation of a Unique Crystal Morphology for the Poly(ethylene glycol)−Poly(ε-caprolactone) Diblock Copolymer

The crystallization behaviors of the poly(ethylene glycol)-poly(epsilon-caprolactone) diblock copolymer with the PEG weight fraction of 0.50 (PEG(50)-PCL(50)) was studied by DSC, WAXD, SAXS, and FTIR. A superposed melting point at 58.5 degrees C and a superposed crystallization temperature at 35.4 degrees C were obtained from the DSC profiles running at 10 degrees C/min, whereas the temperature-dependent FTIR measurements during cooling from the melt at 0.2 degrees C/min showed that the PCL crystals formed starting at 48 degrees C while the PEG crystals started at 45 degrees C. The PEG and PCL blocks of the copolymer crystallized separately and formed alternating lamella regions according to the WAXD and SAXS results. The crystal growth of the diblock copolymer was observed by polarized optical microscope (POM). An interesting morphology of the concentric spherulites developed through a unique crystallization behavior. The concentric spherulites were analyzed by in situ microbeam FTIR, and it was determined that the morphologies of the inner and outer portions were mainly determined by the PCL and PEG spherulites, respectively. However, the compositions of the inner and outer portions were equal in the analysis by microbeam FTIR.

Poly(ethylene glycol)−Oligolactates with Monodisperse Hydrophobic Blocks: Preparation, Characterization, and Behavior in Water

Methoxypoly(ethylene glycol)-b-oligo-L-lactate (mPEG-b-OLA) diblock oligomers with monodisperse OLA blocks were obtained by fractionation of polydisperse block oligomers using preparative HPLC. The fractionated oligomers were composed of an mPEG block with a molecular weight of 350, 550, or 750 and an OLA block with a degree of polymerization of 4, 6, 8, or 10. The diblock oligomers with a low PEG content were fully amorphous, with glass transition temperatures ranging from -60 to -20 degrees C, indicating that the blocks were miscible. Upon heating aqueous dispersions of the block oligomers, cloud points, depending on the PEG/OLA ratio of the block oligomer, were observed at temperatures above 40 degrees C. The monodispersity of the hydrophobic block enabled the amphiphilic molecules to form nanoparticles in water with a hydrodynamic radius of 130-300 nm, at concentrations above the critical aggregation concentration (0.4-1 mg/mL), whereas polydisperse mPEG-b-OLAs gave formation of large aggregates. Static light scattering measurements showed that the nanoparticles have a low density (0.6-25 mg/mL), indicating that the particles are highly hydrated. In agreement herewith, the (1)H NMR spectra of nanoparticles in D2O closely resembled spectra in a good solvent for both blocks (CDCl3). It is therefore suggested that the nanoparticles contain a hydrated core of mPEG-b-OLA block oligomers, stabilized by a thin outer PEG layer. The particles were stable for two weeks, except for the mPEG350 series and mPEG750-b-OLA4, indicating that both the PEG block size and the PEG weight fraction of the oligomers determine their stability. The evident self-emulsifying properties of mPEG-b-oligo-l-lactates with monodisperse hydrophobic blocks as demonstrated in this study, together with their expected biocompatibility and biodegradability, make these systems well suitable for pharmaceutical applications.

Cover Picture: Macromol. Theory Simul. 1/2005

Cover: Distinct diffusion coefficients (${\rm D}^d_{ii}$, ${\rm D}^d_{i0}$ and ${\rm D}^d_{00}$) in the number fixed reference frame, DDCs, for the binary mixture PEG 200‐water as a function of the PEG weight fraction (Xg) are drawn. Values are evaluated according to the equation reported, where xi is a positional coordinate of a particle of species i, pointed brackets represent a canonical ensemble average, V is the total volume, N is the total number of particles in the system, t is the time. Real DDCs, in blue, are compared with a novel hard‐sphere (HS) based standard reference, in red.Further details can be found in the Full paper by A. Vergara on page 21.

Rigidity of Two-Component Hydrogels Prepared from Alginate and Poly(ethylene glycol)−Diamines

Alginate hydrogels have been attractive for a variety of biomedical applications, but they possess limited mechanical properties when ionically cross-linked with divalent cations. Therefore, covalent cross-linking of alginate with poly(ethylene glycol)−diamines of various molecular weights was investigated as a means to generate hydrogels with a range of mechanical properties. Hydrogels with a range of elastic moduli could be generated by controlling either the chain length of the cross-linking molecule or the cross-linking density. The elastic modulus increased gradually with an increase in cross-linking density or weight fraction of PEG in the hydrogel up to ∼27% (w/w) of PEG. The change of mechanical properties was interpreted in terms of molecular weight between cross-links (Mc) according to the rubber-elasticity model, and the results of this analysis were generally consistent with the measured PEG−diamine incorporation efficiencies in this range. However, as the weight fraction of PEG in the hydroge...

Clonazepam release from bioerodible hydrogels based on semi-interpenetrating polymer networks composed of poly(ε-caprolactone) and poly(ethylene glycol) macromer

Poly(ethylene glycol)(PEG) macromers terminated with acrylate groups and semi-interpenetrating polymer networks (SIPNs) composed of poly(ε-caprolactone)(PCL) and PEG macromer were synthesized to obtain a bioerodible hydrogel. Polymerization of PEG macromer resulted in the formation of cross-linked gels due to the multifunctionality of macromer. Glass transition temperature ( T g) and melting temperature ( T m) of PEG networks and PCL in the SIPNs were inner-shifted, indicating an interpenetration of PCL and PEG chains. Water content in the SIPNs increased with increasing PEG weight fraction due to the hydrophilicity of PEG. The amount of clonazepam (CNZ) released from the SIPNs increased with higher content in the SIPNs, lower drug loading, lower concentration of PEG macromer during the SIPNs preparation, and higher molecular weight of PEG. In particular, a combination with low PEG content and low CNZ solubility in water led to long-term constant release from these matrices in vitro and in vivo.