PEG Samples Research Articles

Discrete Libraries of Amphiphilic Poly(ethylene glycol) Graft Copolymers: Synthesis, Assembly, and Bioactivity.

Poly(ethylene glycol) (PEG) is an important and widely used polymer in biological and pharmaceutical applications for minimizing nonspecific binding while improving blood circulation for therapeutic/imaging agents. However, commercial PEG samples are polydisperse, which hampers detailed studies on chain length-dependent properties and potentially increases antibody responses in pharmaceutical applications. Here, we report a practical and scalable method to prepare libraries of discrete PEG analogues with a branched, nonlinear structure. These lipid-PEG derivatives have a monodisperse backbone with side chains containing a discrete number of ethylene glycol units (3 or 4) and unique functionalizable chain ends. Significantly, the branched, nonlinear structure is shown to allow for efficient nanoparticle assembly while reducing anti-PEG antibody recognition when compared to commercial polydisperse linear systems, such as DMG-PEG2000. By enabling the scalable synthesis of a broad library of graft copolymers, fundamental self-assembly properties can be understood and shown to directly correlate with the total number of PEG units, nature of the chain ends, and overall backbone length. These results illustrate the advantages of discrete macromolecules when compared to traditional disperse materials.

In situ PEGylation of polyamide network of thin film composite membrane by inter-polymer H-bond complex formation

Fouling propensity of membranes is a bottleneck problem. PEGylation is an effective approach to improve the antifouling property of a polyamide (PA) thin film composite (TFC) membrane. However, reactive PEG involves in the covalent network formation with PA leading to the increase of network pore size and lowers the rejection efficiency of the membranes. Post-surface modification by reactive PEG leads to lowering of permeates flux. End-functional (reactive) PEG samples are costly and prepared by multi-step process. Herein, the high pKa value of the fraction of –COOH groups of PA network is utilized for the formation of stable complex with PEG. Addition of linear PEG into the aqueous solution of m-phenylenediamine during interfacial polymerization leads to grafting of polyamide network by PEG through the formation of interpolymer H-bond complex of ether oxygen of PEG and –COOH groups of cross-linked PA network. PEG in the PA network increases the hydrophilicity, permeate flux, rejection efficacy and antifouling property of the membranes. The PEG chains remain stable in the PA network in the pH window of acidic to ≤8 as confirmed by the ATR-IR, wetting behavior, model spectroscopic experiments and X-Ray photoelectron spectroscopy. A PEGylated membrane prepared by the in situ addition of PEG (molecular weight 2000 g mol−1, 1% w v−1) into the MPD solution shows 20–30% higher permeate water flux, superior salt rejection efficiency and fouling resistant property than that of a pristine membrane. This approach is simple, cost-effective and easy to implicate.

Study of the PEG content effect on some properties of the PVA/PEG-EY films using the Raman, positron annihilation and impedance spectroscopies

PVA/PEG-EY blend structures are synthesized with PEG concentrations of 0, 1, 3, 5, 10, 15 and 20 wt% using casting method. The electrical and dielectric properties of the blend samples were studied with frequency in range (0.1 Hz to 20 MHz), via impedance spectroscopy. The Raman spectroscopy characterized and distinguish the structure of the prepared films. Theoretical results of Raman spectra of PVA, PEG and EY samples were analyzed based on linear response time-dependent density functional theory and then compared with experimental results of the samples. The microstructure and defect distribution of the synthesized samples were inferred using the positron annihilation spectroscopy (PAS). Experimental and theoretical Raman analysis indicates the increase of diffusion of EY and PEG. Broadband dielectric spectroscopy investigation on a broad range of frequencies shows that the enhancement of electrical conductivity of the prepared PVA/PEG-EY film with increasing PEG content. The considerable effect of the PEG content on the film microstructure was approved. The interactions between the PVA and PEG through the formation of hydrogen bonding modify the size and concentration of the free volume holes.

Effect of drought stress induced by PEG 6000 on Ocimum basilicum L. aroma profile

The present study was aimed to examine the effect of applied drought stress using different rates of PEG 6000 (polyethylene glycol) on morphology, stomatal closure, chemical structure, and volatile profile of basil. Expectedly, the highest shoot and root lengths observed at control were 16.2 cm and 15% PEG treatments (7.5 cm), respectively. Stomatal openness apparently closed with an increasing rate of drought. Release of volatile compounds from the basil leaves was increased with the increased rate of the applied drought stress and aroma profile of dominant volatiles. Terpenes were found to be the most abundant chemical group and their concentrations altered significantly with PEG treatments. Methyleugenol was detected as the major terpene in control, and 5% and 10% PEG samples, while linalool was the prominent compound in 15% PEG sample. FTIR spectrum supported the GC results being differentiated significant, especially in the fingerprint region. Novelty Impact Statement This study is a first proof of the relationship between aroma and drought stress induced by PEG 6000 in Ocimum basilicum. Drought stress simulators such as PEG 6000 showed a significant impact on morphology and aroma compounds. Additionally it is proved that this chemical is not penetrable for the plant and therefore it can be used or controlled as an aroma enhancer.

Effect of PEG Addition on an SnO2 Gas Sensor Fabricated Using Spin Coating

Tin dioxide (SnO2) and tin dioxide: polyethylene glycol (SnO2: PEG) nano-composite thin films, at 10 and 20 wt % PEG, were fabricated by spin coating techniques from a mixed solution of ethanol and water. The structural, morphological, and optical properties of the prepared samples were examined to study the effect of PEG addition on SnO2 thin film properties. X-ray diffraction shows a polycrystalline structure for all samples, where the crystalline size reduced from 8.3 nm (for the pure sample) to 7.2 nm (for the 20% PEG sample). The addition of PEG with the precursors significantly affected the growth behaviour of SnO2 nanoparticles, where the nanoparticle diameter reduced and the connection between them was enhanced forming a continuous structure with pores that enhance gas sensitivity. The hydrogen (H2) gas sensitivity, for the prepared SnO2 and SnO2:PEG samples, increased by increasing the PEG content from 0 to 20% by about four times. The optimum sensitivity was at the working temperature of 100 °C. The gas sensitivity was exponentially dependent on H2 gas concentration across a concentration range of 100 to 4000 ppm.

Laboratory evaluation of poly(ethylene glycol) for cooling of asphalt pavements

Poly(ethylene glycol) (PEG) is a latent heat storage material that has potential to regulate the thermal environment within the asphalt pavement via phase-transition process. However, the properties of PEG vary in terms of its average molecular weight. The PEG selection principle is put forward in this study, which is to not only realize satisfactory cooling function but also minimize the adverse effects on asphalt properties. For illustration, the phase change behaviors and thermal stability of PEG were first studied. It is demonstrated that the PEG samples with its average molecular weight within 2000 ~ 20000 (PEG-2 K ~ 20 K) are characterized by suitable phase change temperatures of 41.27 ~ 62.39 °C, fairly great latent heats of 184.8 ~ 211.9 J·g−1 and excellent thermal stability below 300 °C. The larger molecular weight generally corresponds to the higher phase change temperatures, whereas the greatest latent heats occur at PEG-8 K. Despite that, there are marginal differences among the phase change properties of PEG-4 K ~ 8 K. To further select the ideal PEG, tests for asphalt properties were conducted. Results show that based on the negative role of PEG in the high- and low-temperature properties, temperature and stress sensitivities of asphalt binder, it is necessary to encapsulate PEG before use. Therefore, these detrimental roles are required to be considered when selection of PEG. In terms of our selection principle proposed, PEG with a large average molecular weight is usually preferred except PEG-20 K.

Clinical and economic outcomes of pegfilgrastim in metastatic colorectal cancer.

6636 Background: Febrile neutropenia (FN) resulting from myelosuppressive chemotherapy can lead to increased hospitalizations and mortality. Pegfilgrastim can be used to reduce the risk of FN; however, few studies address pegfilgrastim’s value in patients with metastatic solid tumors. This observational study compared outcomes for pegfilgrastim-treated (peg-tx) and peg-untreated (no peg) patients with metastatic colorectal (CRC) at US Oncology practices (USO) participating in the Oncology Care Model. Methods: Patients with metastatic CRC treated at USO from July 1, 2013 – December 31, 2014 and a qualifying baseline OCM episode were included. Propensity scoring was used to match (1:2) peg-tx and no peg cohorts based on line of therapy, number of comorbidities, age, gender, ECOG performance status, chemotherapy neutropenic fever risk, and dose reduction. Outcomes assessed included all-cause and infection-related hospitalization rates; total cost of care per 6-month OCM episode; and overall survival (OS). Results: Matched peg-tx and no peg samples were 149:298. The all-cause hospitalization rate was higher in the peg-tx vs. no peg population, 45% vs. 32% (OR 1.7, (1.1, 2.5), p = 0.011). Infection-related hospitalization rates were no different in peg-tx vs. no peg cohorts, p = 0.367. Cost of care was significantly higher for peg-tx patients vs. no peg ($58,787 ± $20,490 vs. $37,811 ± $19,593 respectively, p < .001). OS was 19.5 months (peg-tx) vs. 19.7 months (no peg), p = 0.882. Conclusions: While peg use in curative treatment settings for high risk patients is standard of care, in our Medicare population use in metastatic CRC did not result in a lower all-cause or infection-related hospitalization rate or impact in OS. There was a higher 6-month total cost of care associated with those patients who received peg during chemotherapy.

Influence of Additives on Formation of through-Si Via in Si Substrate Using Metal Assisted Chemical Etching

Recently, metal assisted chemical etching (MacEtch) attracts attention to fabricate a nano/microscale structures in Si substrate, such as nanowire and nanohole arrays. In this method, using a noble metal as a catalyst, only Si under the catalyst is selectively etched in the etching solution. Several papers have been already reported on the formation of microscale patterning using MacEtch. However, it is difficult to obtain high aspect vertical holes using MacEtch process because of its instability of etching direction for prolonged process as shown in figure (a). In this study, we present a new approach using surfactant agents as an additive in MacEtch solution to obtain vertical Si holes in Si substrates. Microscale holes were prepared in Si (100) substrates using the MacEtch process with a disc-shape patterned Au catalyst. The patterned Au discs ( 10 μm in diameter), which were deposited on a Ti / Si substrate using a photolithography lift-off process. For the MacEtch process, a mixture of hydrofluoric acid (HF), hydrogen peroxide (H2O2) and deionized water was used as the base etching solution. The PEG was added to the etching solution as an additive. The MacEtch of the Si substrate with patterned Au were performed for 120 min at 40 oC in the etching solution. Figure (a) shows cross-sectional SEM images of typical morphology of etched Si using MacEtch process without PEG in the etching solution. The etching direction of Si were changed during MacEtch as indicated with dashed arrow in Fig. (a), and these phenomena were observed in more than 60 % Si holes etched with MacEtch without PEG. Adding PEG in the etching solution, drastic improvement in verticality of etched Si holes were observed. Almost all holes were vertically etched to the Si substrate in PEG samples, and typical cross-sectional image of the etched holes is shown in Fig. (b). Fig. (c) and (d) shows enlarged image of Au catalyst films after MacEtch process. The catalyst in the bended hole prepared without PEG was deformed and partially detached from Si substrate, shown in Fig. (c). In contrast, in the case of straight holes etched with PEG shown in Fig. (d), the catalyst tightly contacted to the substrate, and showed relatively less defamation. Thus, there is a strong correlation between defamation of catalyst and formation of bended hole. The detailed mechanism of PEG additive in etching solution during Macetch process and the MacEtch results using other surfactants as additives will be presented. Figure 1

Difference in dilute aqueous solution behavior between poly(ethylene glycol) and poly(ethylene oxide)

Static light scattering behavior was examined for poly(ethylene glycol) (PEG) and poly(ethylene oxide) (PEO) of small weight-average molecular weight M w (3 × 103−2 × 104), in methanol and water at 25.0 °C, the former polymer having hydroxy groups at both ends and the latter having a methoxy group at one end and a hydroxy group at the other. It was found that some aggregates of large size are formed in aqueous solutions of the PEO samples with M w = 3.81 × 103 and 7.00 × 103, while all PEG and PEO samples are isolated in methanol solutions, and the PEG samples and the PEO sample of the largest M w (=1.60 × 104) are also isolated even in the aqueous solutions. From the results of dynamic light scattering measurements for the aqueous solution of the PEO sample with M w = 3.81 × 103 at 25.0 °C, there were detected two classes of scatterers having different sizes, i.e., the isolated chains and aggregates, the apparent hydrodynamic radius of the latter being ca. twenty times as large as that of the former. Static light scattering measurements are carried out for poly(ethylene glycol) and poly(ethylene oxide) (PEO) of the weight-average molecular weight M w ranging from 3×103 to 2×104 in methanol and water at 25.0 °C. Some aggregates of large size are found to be formed only in the cases of PEO of M w∼O(103) in aqueous solutions, although for other cases polymer chains are isolated in solutions.

Characterization of polylactide/poly(ethylene glycol) blends via direct pyrolysis mass spectrometry

In this study, melt blended poly(lactic acid) and poly(ethylene glycol), (PLA)/PEG samples involving 10, 15 and 20wt% PEG were prepared and characterized by direct pyrolysis mass spectrometry technique in addition to classical techniques such differential scanning calorimetry, thermogravimetric analyses and mechanical tests. The incorporation of PEG resulted in consistent and significant decrease in the tensile strength and modulus, and reduction in endothermic melting peak of PLA due to the plasticizing effect of PEG with the virgin PLA matrix. Both TGA and DP-MS analyses pointed out that the thermal decomposition of the blend occurred mainly in two steps. In addition, the pyrolysis mass spectrometry analyses indicated presence of chains generated by the interactions of ether linkages of PEG and COOH groups of PLA, present either as end groups or due to reactions with water, during the blending and/or pyrolysis process. As a consequence, decrease in the thermal stability of PEG chains was detected. Analyses of the blends prepared by solution mixing for variable periods confirmed that these interactions took place mainly during the blending process. In addition, increase in the thermal stabilities of both components for the blends prepared by stirring for prolonged times was detected and associated with generation of a crosslinked structure.

Thermal evolution of PEG-based and BRIJ-based hybrid organo-inorganic materials. FT-IR studies

This work presents the application of FT-IR spectroscopy to study the thermal evolution of PEG-based nanocomposites prepared using montmorillonite STx intercalated with polyethylene oxides PEG 1500 and PEG 4000 and polyethylene oxide BRIJ. The effect of different polymer molecular weights and polymer loadings has been evaluated by means of diagnostic mid-IR bands. PEG fragmentation through the cleavage of the CO bond appears to be the main reaction step, leading to the formation of short chain carbonyl adsorbed species (such as acetaldehyde), alcohols (ethanol and methanol) and, to a lesser extent, esters species, characterized by the frequency of the carbonyl stretching band. The detection of carbonyl band evidenced the formation of partial oxidation products as first step of the thermal degradation.Increasing polymer loadings, as well as increasing polymer molecular weight leads to lower temperature of formation of the first oxidation products. No clear indication of the effect of the chemical nature for the intercalated polymers can be obtained. BRIJ thermal decomposition seems to be mainly driven by the PEG-like moiety chemistry.CH stretching bands detected at 450–500°C for the samples intercalated with PEG samples indicated the formation of residual organic compounds resisting oxidation, possibly char species preserved from further oxidation by the interlayer galleries.

Determination of Free Polyethylene Glycol in Cross-Linked Sodium Hyaluronate Gel

Abstract: In this study we present a method for the determination of free polyethylene glycol in a gel. We detect the PEG residues of cross-linked sodium hyaluronate gel by spectrophotometry. The pretreatment of cross-linked sodium hyaluronate gel is special and the plot of working curve is unconventional. The precision, the recovery rate with marker, the reliability and repeatability of this method are tested and verified. The results indicated that the method has an excellent linear relationship in the range of 0-40.5µg mL-1. The regression equation is Y=0.0108X+0.2047 (R2=0.9994). The standard deviation of the detection method is 1.10% (n=9). The recovery rate with marker is 97.8% and the repeatability is perfect. In conclusion, the method possesses the properties of simple operation, quickness, excellent stability. Moreover this method can be applied for the quality control of gel products cross-linked by PEG and liquid samples containing PEG.

Effects of plasticizer on the mechanical properties of kenaf/starch bio-composites

Research and development of biodegradable bio-composite can replacement the synthetic polymer materials, which is used for automobile interior materials, finishing materials of air conditioner and refrigerator. To develop both components as biodegradable bio-composite, this research used natural polymer starch as matrix and kenaf fiber as a filler. Various plasticizer(polyvinyl alcohol, polyethylene glycol, glycerol) were added and examined the mechanical properties of the kenaf/starch bio-composites according to these plasticizer. The kenaf bast which cultivated in Korea was retted with 2 % NaOH solution. The plasticizer weighting 10 % of that of matrix was added. kenaf/starch composites were molded with hot press for 30 minutes at 130 °C and 3,500 PSI molding condition. The mechanical properties such as tensile strength, elongation, and young modulus of the kenaf/starch composites were measured. Also, we measured the SEM cross-section images in order to investigate interfacial adhesion properties of fractured surfaces. The order of strength size of composites were G (12.42 MPa) > PVA (9.72 MPa) > PEG (4.73 MPa) samples respectively. The tensile strength of PEG sample is lower than the control sample (5.40 MPa).

Characterization of polymeric films subjected to lithium ion beam irradiation

Two different polymeric materials that are candidate materials for use as binders for mixed uranium–plutonium oxide nuclear fuel pellets were subjected to Li ion beam irradiation, in order to simulate intense alpha irradiation. The materials (a polyethylene glycol 8000 and a microcrystalline wax) were then analyzed using a combination of mass spectrometry (MS) approaches and X-ray photoelectron spectroscopy (XPS). Samples of the irradiated PEG materials were dissolved in H2O and then analyzed using electrospray ionization-MS, which showed the formation of a series of small oligomers in addition to intact large PEG oligomers. The small oligomers were likely formed by radiation-induced homolytic scissions of the C–O and C–C bonds, which furnish radical intermediates that react by radical recombination with H and OH. Surface analysis using SIMS revealed a heterogeneous surface that contained not only PEG-derived polymers, but also hydrocarbon-based entities that are likely surface contaminants. XPS of the irradiated PEG samples indicated the emergence of different carbon species, with peak shifts suggesting the presence of sp2 carbon atoms. Analysis of the paraffinic film using XPS showed the emergence of oxygen on the surface of the sample, and also a broadening and shifting of the C1s peak, demonstrating a change in the chemistry on the surface. The paraffinic film did not dissolve in either H2O or a H2O–methanol solution, and hence the bulk of the material could not be analyzed using electrospray. However a series of oligomers was leached from the bulk material that produced ion series in the ESI-MS analyses that were identified octylphenyl ethoxylate oligomers. Upon Li ion bombardment, these shifted to a lower average molecular weight, but more importantly showed the emergence of three new ion series that are being formed as a result of radiation damage. Surface analysis of the paraffinic polymers using SIMS produced spectra that were wholly dominated by hydrocarbon ion series, and no difference was observed between unirradiated and irradiated samples. The studies demonstrate that for the PEG-based polymers, direct evidence for radiolytic scission can be observed using ESI-MS, and suggests that both radiolytic pathways and efficiencies as a function of dose should be measurable by calibrating instrument response to the small oligomeric degradation products.

Fabrication of poly- DL-lactide /polyethylene glycol scaffolds using the gas foaming technique

The aim of this study was to prepare poly- DL-lactide/polyethylene glycol (P DLLA/PEG) blends to improve medium absorption and cell proliferation in the three-dimensional (3-D) structure of their scaffolds. Carbon dioxide (CO 2) was used as a foaming agent to create porosity in these blends. The results of Fourier transform infrared (FTIR) spectroscopy demonstrated that the blends were homogeneous mixtures of P DLLA and PEG. The peak shifts at 1092 and 1744 cm −1 confirmed the presence of molecular interactions between these two compounds. Increasing the PEG weight ratio enhanced the relative crystallinity and hydrophilicity. The P DLLA/PEG blends (especially 80/20 and 70/30 weight ratios) exhibited linear degradation profiles over an incubation time of 8 weeks. The mechanical properties of P DLLA/PEG blends having less than 30 wt.% PEG were suitable for the fabrication of porous scaffolds. Increasing the concentration of PEG to above 50% resulted in blends that were brittle and had low mechanical integrity. Highly porous scaffolds with controllable pore size were produced for 30 wt.% PEG samples using the gas foaming technique at temperatures between 25 and 55 °C and pressures between 60 and 160 bar. The average pore diameters achieved by gas foaming process were between 15 and 150 μm, and had an average porosity of 84%. The medium uptake and degradation rate of fabricated P DLLA/PEG scaffolds were increased compared with neat P DLLA film due to the presence of PEG and porosity. The porous scaffolds also demonstrated a lower modulus of elasticity and a higher elongation at break compared to the non-porous film. The fabricated P DLLA/PEG scaffolds have high potential for various tissue-engineering applications.

Photodynamic Antitumor Activity of Fullerene Modified with Poly(ethylene glycol) with Different Molecular Weights and Terminal Structures

The objective of this study is to investigate the effect of molecular size and terminal structure of poly(ethylene glycol) (PEG) on the antitumor activity of PEG-modified fullerene (C60). PEG samples with different terminal structures and molecular weights were covalently coupled to C60 and their superoxide anion generation, in vitro or in vivo antitumor activity, and body distribution were assessed for the effect of the photosensitizer, used in photodynamic therapy (PDT), on the tumor. Irrespective of the molecular weight and terminal structure of PEG used, the C60–PEG conjugates exhibited a similar ability of superoxide anion generation and in vitro antitumor activity. On the contrary, a strong suppression of the in vivo tumor growth was observed for the C60–PEG conjugates prepared with methyl-terminated PEG with the highest molecular weight, which showed the longest half-life period in the blood circulation and the highest tumor accumulation among all the conjugates used. It is concluded that the superior tumor targetability of C60–PEG conjugates is one of the keys to enhance the PDT activity.

A simple and green procedure to prepare poly(ethylene glycol) networks: Synthesis and properties

Poly(ethylene glycol) networks have been prepared by reaction between dihydroxy-terminated poly(ethylene glycol) (PEG) and diepoxy-terminated poly(ethylene glycol) (DEPEG) (M ≈ 600 g mol−1) in concentrated aqueous NaOH solutions by a process involving alkoxide–epoxy-type reactions. Yields of formation of the networks depend on the concentration of NaOH used, being maximum (>80%) for concentrations of 20% by weight. The PEG/DEPEG molar ratio in the feed plays a decisive role in both the yield of the reaction and the properties of the obtained network, controlling the degree of crosslinking. High PEG/DEPEG ratios lead to hydrogels with a great swelling capacity. The swelling capacity can also be controlled by varying the PEG molecular weight for a same PEG/DEPEG ratio. By employing PEG samples of molecular weights 600, 1500 and 3000 g mol−1, and different PEG/DEPEG ratios, hydrogels with degrees of swelling ranging from 3.4 to 21.6 have been obtained. The thermal transitions in the networks, i.e. the glass transition (Tg) and/or the melting temperature (Tm) show a linear dependence on the PEG/DEPEG ratio.

Electron-Beam-Initiated Polymerization of Poly(ethylene glycol)-Based Wood Impregnants

The current study demonstrates that methacrylate and acrylate poly(ethylene glycol) (PEG) functional oligomers can be effectively impregnated into wood blocks, and cured efficiently to high conversions without catalyst by e-beam radiation, allowing for less susceptibility to leaching, and favorable properties including higher Brinell hardness values. PEG based monomers were chosen because there is a long history of this water-soluble monomer being able to penetrate the cell wall, thus bulking it and decreasing the uptake of water which further protects the wood from fungal attack. Diacrylate, dimethacrylate, and dihydroxyl functional PEG of M(w) 550-575, of concentrations 0, 30, 60, and 100 wt % in water, were vacuum pressure impregnated into Scots Pine blocks of 15 × 25 × 50 mm in an effort to bulk the cell wall. The samples were then irradiated and compared with nonirradiated samples. It was shown by IR, DSC that the acrylate polymers were fully cured to much higher conversions than can be reached with conventional methods. Leaching studies indicated a much lower amount of oligomer loss from the cured vinyl functional PEG chains in comparison to hydroxyl functional PEG indicating a high degree of fastening of the polymer in the wood. The Brinell hardness indicated a significant increase in hardness to hardwood levels in the modified samples compared to the samples of hydroxyl functional PEG and uncured vinyl PEG samples, which actually became softer than the untreated Scots Pine. By monitoring the dimensions of the sample it was found by weight percent gain calculations (WPG %) that water helps to swell the wood structure and allow better access of the oligomers into the cell wall. Further, the cure shrinkage of the wood samples demonstrated infiltration of the oligomers into the cell wall as this was not observed for methyl methacrylate which is well-documented to remain in the lumen. However, dimensional stability of the vinyl polymer modified blocks when placed in water was not observed to the same extent as PEG.

Solubility profiles of poly(ethylene glycol)/solvent systems. II. comparison of thermodynamic parameters from viscosity measurements

AbstractSolution thermodynamics of PEG samples in aqueous and nonaqueous (methanol, chloroform, tetrahydrofuran, and dimethylsulfoxide) solutions have been investigated by viscometric studies at 25, 30, 35, and 40°C. The hydrodynamic expansion factor, ah, and the unperturbed root mean square end‐to‐end distance, $ \langle r^{2}\rangle_\theta^{1/2} $, found for the system indicated that the polymer coils contract as the temperature is raised. The long‐range interaction parameter, B, was also evaluated and a significant decrease with increasing temperature was observed. The theta temperatures, θ, obtained from the temperature dependence of (1/2 − χ) and the second virial coefficient, A2, are quite good in agreement with the calculated values evaluated via extrapolation and interpolation methods. The thermodynamic interaction parameter, χ, was evaluated through the sum of the individual values of enthalpy and entropy dilution parameters for PEG samples. The restrictions applying to the establishment of concentration regimes, short‐range, and long‐range interactions are discussed. A parallelism is found between solubility profiles obtained by solution viscometry and solubility parameter approaches for PEG/solvent systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Calibration of chromatographic systems for quantitative prediction of chromatography of homopolymers

A method is proposed for obtaining from the experimental data the main parameters, which determine the chromatographic behavior of homopolymers: a dependence of the adsorption interaction parameter on the mobile phase composition, and the pore volume and pore size values. The interaction parameter can be determined by this method in both adsorption, critical, and SEC-type regimes of chromatography. The method is tested in 'mathematical experiments' with theoretical data that mimic experiments, and is applied to calibrate real chromatographic systems. With the obtained calibrations quantitative modeling of chromatograms of PEG samples on two typical ODS columns with different pore size in methanol/water and acetone/water mixed solvents is performed; the simulation results are compared with real chromatograms.