Ethylene Propylene Oxide Research Articles

Three-liquid-phase extraction systems for separation of phenol and p-nitrophenol from wastewater

Several new three-liquid-phase extraction systems containing ethylene oxide–propylene oxide (EOPO) random copolymers have been developed. These systems were used for treating simulated wastewater containing phenol and p-nitrophenol ( p-NP). Effects of pH, phase-forming components and their concentrations on partition behaviors of phenolic compounds were investigated. Results showed that phenol and p-NP could be unevenly and efficiently partitioned among the phases at pH 9.3, with about 80% phenol in the top phase and 95% p-NP in middle phase, respectively. Separation factor of two compounds increased remarkably with the increase of pH from 4.0 to 10.0. The three-liquid-phase system containing poly(ethylene glycol-ran-propylene glycol) and butyl acetate (BA) was proved to be suitable for phenol and p-NP separation. The separation factor was over 13 at pH 8.43.

Process integration for production of 6-aminnopenicillanic acid from penicillin G fermentation broth

A novel process for 6-aminnopenicillanic acid (6-APA) production from penicillin G fermentation broth was developed, which integrated some new technologies such as three-liquid-phase extraction and solvent sublation. A new three-liquid-phase extraction system containing ethylene oxide-propylene oxide (EOPO) random copolymer was used to separate and purify penicillin G from its filtrated broth and trace organic extractant in the aqueous phase of back-extraction was removed by solvent sublation. Experimental results showed that above 90% of penicillin G could be distributed into the upper organic phase at pH below 3.0, and most of impurities and some phenylacetic acids (PAA) were partitioned into the copolymer-rich middle phase. About 70% organic solvent could be stripped by one-step solvent sublation from penicillin G aqueous solution. The purity of 6-APA produced by the above-simplified process could be above 98% and other quality parameters reached the level of the conventional process.

Improving the Infiltration of Water through Repellent Soils Using Synergistic Surfactant Blends Based on Alkyl Glucosides and Ethylene Oxide-Propylene Oxide Block Copolymers

Abstract Soil water repellency arises as a consequence of initial soil water content and the type of organic matter incorporated into or adsorbed onto the individual soil particles. Water repellent soils create significant agronomic and hydrologic challenges, retarding water infiltration into the soil profile and often rendering entire areas impervious to water penetration. These soils often prevent effective wetting of the rootzone during precipitation or irrigation and lead to increased runoff and leaching of pesticides, fertilizers, and other amendments. Agriculturalists have approached the soil water repellency problem through the use of wetting agent surfactant compositions. The degree of wetting efficacy among surfactant chemistries and formulations has varied significantly. The wetting characteristics of alkyl glucosides and ethylene oxide-propylene block copolymers, two nonionic surfactant classes, were evaluated in the context of improving the infiltration of water through water repellent soil profiles. A laboratory column test was used to measure the initial effectiveness of the wetting agent compositions on synthetically hydrophobized and naturally water repellent soils. A synergistically enhanced wetting rate occurred when the alkyl glucoside to block copolymer ratio was from approximately 6:1 to 0.5:1 by weight, ideally when the ratio was from approximately 4:1 to 0.7:1. Within these ratios, synergism was inversely proportional to the HLB and proportional to the molecular weight of the block copolymer used. This research is the first to demonstrate the promising effects of formulations comprising alkyl glucosides and EO/PO block copolymers on improving the distribution and dynamics of water in repellent soils.

Differences in the adsorption behaviour of poly(ethylene oxide) copolymers onto model polystyrene nanoparticles assessed by isothermal titration microcalorimetry correspond to the biological differences

The adsorption behaviour of a tetrafunctional copolymer of poly (ethylene oxide)-poly (propylene oxide) ethylene diamine (commercially available as Poloxamine 908) and a diblock copolymer of poly (lactic acid)-poly (ethylene oxide) (PLA/PEG 2:5) onto a model colloidal drug carrier (156 nm sized polystyrene latex) is described. The adsorption isotherm, hydrodynamic thickness of the adsorbed layers and enthalpy of the adsorption were assessed. The close similarity in the conformation of the poly (ethylene oxide) (PEO) chains (molecular weight 5000 Da) in the adsorbed layers of these two copolymers was demonstrated by combining the adsorption data with the adsorbed layer thickness data. In contrast, the results from isothermal titration microcalorimetry indicated a distinct difference in the interaction of the copolymers with the polystyrene colloid surface. Poloxamine 908 adsorption to polystyrene nanoparticles is dominated by an endothermic heat effect, whereas, PLA/PEG 2:5 adsorption is entirely an exothermic process. This difference in adsorption behaviour could provide an explanation for differences in the biodistribution of Poloxamine 908 and PLA/PEG 2:5 coated polystyrene nanoparticles observed in previous studies. A comparison with the interaction enthalpy for several other PEO-containing copolymers onto the same polystyrene colloid was made. The results demonstrate the importance of the nature of the anchoring moiety on the interaction of the adsorbing copolymer with the colloid surface. An endothermic contribution is found when an adsorbing molecule contains a poly (propylene oxide) (PPO) moiety (e.g. Poloxamine 908), whilst the adsorption is exothermic (i.e. enthalpy driven) for PEO copolymers with polylactide (PLA/PEG 2:5) or alkyl moieties.

Influence of the Hydrotrope Structure on the Physical Chemical Properties of Polyoxide Aqueous Solutions

The physical chemical properties of block substituted poly(ethylene oxide-propylene oxide) (PEO-PPO) block copolymer aqueous solutions were evaluated in the presence of two hydrotropes of different structures: sodium p-toluene sulfonate (NaPTS) and butyl monoglycol sodium sulfonate (NaBMGS). The critical micelle concentration and the cloud point of the copolymer solutions were displaced to higher concentration values, indicating that the solubility of the copolymer was increased in the presence of the hydrotropes. Temperature increased the micelle hydrodynamic radius, but concentration had a limited effect. Carbon-13 nuclear magnetic resonance (13C NMR) permitted the interaction between the surface-active agent and the hydrotrope to be evaluated: NaBMGS, which presented a more pronounced hydrotropic effect, interacts more effectively with the hydrophobic moiety of the surfactant, while NaPTS interacts rather mainly with the hydrophilic oxyethylenic groups. The results furnish experimental evidence to conclude that the hydrotropic phenomenon is specific in relation to both the hydrotrope and the solubilizate.

Substrates do influence the ordering of mesoporous thin films

Two kinds of ordered structures, a cylindrical hexagonal and a compact hexagonal arrangement of micelles, were synthesized using either CTAB or a Pluronic block copolymer as templating agents. The ordering of thin films deposited on glass, dielectrics (Si3N4, SiTiOx) and a metal with a native oxide (Ti) were compared. We observed that the ordered texture of the films was greatly influenced by the substrate. In order to differentiate the effects of surface roughness and surface forces, glass substrates were systematically modified by grafting ethylene oxide/propylene oxide (EO/PO) statistical copolymers. Varying the EO content allowed fine tuning of the hydrophilicity of the surface. In this case, the same phase and quality of ordering as on bare glass is observed but with a systematic higher contraction of the ordered structure. This is ascribed to the similar chemical nature between the grafted substrate and the templating molecules, which fasten the formation of the ordered structure.

Microstructural and conformational studies of polyether copolymers

A combined structural/conformational study of ethylene oxide/propylene oxide (EO/PO) copolymers has been undertaken. Electrospray ionisation (ESI) and matrix-assisted laser desorption/ionisation (MALDI) methods have been utilised and ESI-tandem mass spectrometry (MS/MS) product ion spectra, including accurate mass measurements, utilised to establish fragmentation pathways. This has enabled end group and sequence information to be obtained. Ion mobility mass spectrometry experimental, along with theoretical, approaches has been used in tandem to probe the gas-phase conformation of selected cationised species from the block and random copolymers. The cross-sections established from these measurements and calculations have been shown to be dependent on molecular weight of the oligomer and radii of the cation but largely independent of the sequence of the ion in the gas-phase. The ion mobility results have been used to aid the understanding of the fragmentation of these copolymers by means of ESI-MS/MS.

Quasi-Elastic Neutron Scattering Investigation of Dynamics in Polymer Electrolytes

Polymer dynamics in a cross-linked poly(ethylene oxide-propylene oxide) random copolymer, both neat and doped with an inorganic salt, is investigated by means of quasi-elastic neutron scattering (QENS) as a function of temperature and momentum transfer. Data from a high-resolution backscattering instrument are reported. We present an original approach to the analysis of inelastic fixed energy scans. The findings from this approach lead to a detailed description of the polymer dynamics across the glass transition. The neat polymer dynamics is modeled in terms of two relaxation processes: Below the glass transition, the methyl side group hopping relaxation has been characterized and compared with the similar process occurring in pure poly(propylene oxide). Above the glass transition, a non-Debye, non-Arrhenius relaxation occurs, corresponding to the polymer segmental dynamics. In the case of the salt-doped rubber, the segmental dynamics is found to be more complex: while the methyl group dynamics is not affected by the salt addition, the present data set supports the view of a bimodal segmental dynamics as a consequence of salt addition.

Kinetics of Adsorption and Desorption of PEO−PPO−PEO Triblock Copolymers on a Self-Assembled Hydrophobic Surface

We report on the kinetic behavior of adsorption from solution of a family of triblock copolymers, copoly(ethylene oxide−propylene oxide-ethylene oxide) (PEO−PPO−PEO), on a gold surface modified by a methyl-terminated, self-assembled monolayer (SAM) of a long-chain alkanethiol (CH3 (CH2)10SH). We monitored the kinetics with a surface plasmon resonance (SPR) technique, whose fast time resolution (0.1 s) allowed us to follow the evolution of these systems even for characteristic times of a few seconds. The data were analyzed in the context of a mass transfer corrected Langmuir kinetics model. While the model is only able to reproduce the observations for either very dilute solutions or the initial stages of the process, it nevertheless allows us to discriminate the onset of the different mechanisms of adsorption. This study shows that, for a series of compounds with the same length of the PPO block, the intrinsic kinetics of the adsorption process is affected by the relative balance of the hydrophilic and hydrophobic content within the copolymer: higher hydrophobic content leads to enhanced adsorption rates past the critical micelle concentration (cmc). This is consistent with observations from our earlier study on the morphology of the polymer-coated surfaces by atomic force microscopy.

Determination of cloud-point temperatures for different copolymers

This paper describes a novel system which has a great potential for use for extractions in biotechnological processes as it uses only polymers and can be operated at moderate temperatures and salt concentrations. The polymers used in this work are ethylene oxide-propylene oxide 10:90 (w/w) (EO10PO90) and ethylene oxide-propylene oxide 20:80 (w/w) (EO20PO80). The temperature required for thermoseparation decreases with increasing PO content of the copolymer and increasing buffer concentration.

Moderation of oral bacterial adhesion on saliva-coated hydroxyapatite by polyaspartate

Synthetic sodium alpha,beta-polyaspartate (PA) has been investigated as a moderator of adhesion and the subsequent biofilm formation by oral bacteria. The inhibition of bacterial adhesion by PA was assessed by (i) a 30-min incubation with Streptococcus sanguis in a microtitre assay with the wells coated with hydroxyapatite (HAP) and (ii) an 18-h challenge with human salivary microflora in a HAP disc assay. In contrast to HAP-coated surfaces, clean polystyrene surfaces in the microtitre assay exhibited no anti-adhesion properties. It has been found that PA significantly and similarly adsorbs onto HAP surfaces in the presence and absence of salivary coating. The HAP disc assay also showed that PA, both in aqueous solutions and in toothpaste, reduced the level of adhered microflora and this effect was enhanced by added propylene oxide-ethylene oxide copolymers. The principal finding from this work is the potential role for PA as an inhibitor of dental plaque formation. PA may significantly modify the salivary pellicle. This work indicates the use of PA in controlling the development of dental plaque and the formation of bacterial biofilm in general.

Calorimetry and thermogravimetry as tools for the assessment of the thermal stability of polyoxide-based nonionic surfactants

Differential scanning calorimetry (DSC) and thermogravimetry (TGA) have been used to evaluate the thermal stability of nonionic surfactants. We have studied monofunctional diblock copolymers of poly(ethylene oxide-propylene oxide) (R-PEO–PPO–OH, where R length is linear C 4 or C 12–14) as nonionic surfactants. It was observed that the thermal stability was dependent on the copolymer structure. Moreover, the higher the EO/PO ratio in the copolymers the higher the oxidative thermal stability. The autoxidation exhibits exothermic behaviour and the enthalpy related to the process depends on the EO/PO ratio. The initial temperatures of degradation obtained from DSC and TGA were in agreement.

The characteristics of betamethasone-loaded chitosan microparticles by spray-drying method

Betamethasone (BTM)-loaded microparticles prepared by a spray drying method using chitosan (CTS) as raw material, type-A gelatin and ethylene oxide-propylene oxide block copolymer (Pluronic F68) as modifiers. The BTM-loaded in varied chitosan/Pluronic F68/gelatin microparticle formulations was investigated. By properly choosing excipient type and concentration a high degree of control was achieved over the physical properties of the BTM-loaded microparticles. Microparticle characteristics (zeta potential, tap density, particle size and yield), loading efficiencies, microparticle morphology and in-vitro release properties were examined. Surface morphological characteristics and surface charges of prepared microparticles were observed by using scanning electron microscopy (SEM) and microelectrophoresis. A SEM micrograph shows that the particle sizes of the varied chitosan composed microparticles ranged from 1.1-4.7 μ m and the external surfaces appear smooth. The BTM-loaded microparticles entrapped in the chitosan/Pluronic F68/gelatin microparticles with trapping efficiencies up to 93%, collected yield rate 44%, and mean particle size varied between 1-3 μ m, positive surface charge (20-40 mv), and tap densities (0.04-0.40 g/cm3) were obtained. The collected BTM yield and size of particle was increased with increasing BTM-loaded amount but both zeta potential and tap density of the particles decreased with increasing BTM-loaded amount. The in vitro release of BTM showed a dose-dependent burst followed by a slower release phase that was proportional to the drug concentration in the concentration range between 5-30%w/w. The in vitro drug release from the chitosan/Pluronic F68/gelatin 1/0.1/0.4 microspheres had a prolong release pattern. These formulation factors were correlated to particulate characteristics for optimizing BTM microspheres in pulmonary delivery.

Influence of Cell Opener in High Resilience Molded Polyurethane Foam

In a chemical method for cell opening of high resilience (HR) molded polyurethane (PU) foam, two types of cell openers, the poly(ester-ether) type, PESE, having ester linkage and hydrophilic polyether segment in the molecule and the conventional polyether type, poly(propylene oxide-ethylene oxide), PPEO, were employed. The influence of structure and concentration of cell opener on the kinetics, stability, open cell content and mechanical properties of molded foam were investigated. The PESE-based formulation exhibited delayed reaction times and good stability compared to the PPEO-based formulation. The open cell content increased with cell opener amount and was independent of the cell opener structure. The mechanical properties clearly depend on the structure of cell opener. The PESE-based formulation had improved mechanical properties such as indentation hardness, tensile strength and tear strength. The increase of PPEO concentration significantly deteriorated the molded foam’s mechanical properties, while the foam with PESE gave less deterioration of mechanical properties up to a specific concentration of the PESE. With the above observations, PESE was found to be a useful cell opener for preparation of HR molded PU foam which has acceptable mechanical properties.

Formulation factors in preparing BTM-chitosan microspheres by spray drying method.

Chitosan (CTS) microspheres were prepared by a spray drying method using type-A gelatin and ethylene oxide-propylene oxide block copolymer as modifiers. Surface morphological characteristics and surface charges of prepared microspheres were investigated by using scanning electron microscopy (SEM) and microelectrophoresis. The particle shape, size and surface morphology of microspheres were significantly affected by the concentration of gelatin. Betamethasone disodium phosphate (BTM)-loaded microspheres demonstrated good drug stability (less 1% hydrolysis product), high entrapped efficiency (95%) and positive surface charge (37.5 mV). The in vitro drug release from the microspheres was related to gelatin content. Microspheres containing gelatin/CTS 0.4 approximately 0.6(w/w) had a prolong release pattern for 12 h. These formulation factors were correlated to particulate characteristics for optimizing BTM microspheres in pulmonary delivery.

Gas separation properties of polysiloxane/polyether mixed soft segment urethane urea membranes

In this study, polyurethanes (PUs) and polyurethane ureas (PUUs) based on 4,4′-diphenylmethane diisocyanate (MDI) with poly(tetramethylene oxide) (PTMO), poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), propylene oxide-ethylene oxide triblock copolymer (PEO-PPO-PEO), poly(dimethylsiloxane) (PDMS), and mixed PDMS/PTMO, PDMS/PEO, PDMS/PPO, and PDMS/PEO-PPO-PEO soft segments were synthesized in order to investigate their structures-gas permeation property relations. The mixed PDMS/polyether copolymer membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM) measurements. TEM showed that the mixed PDMS/polyether copolymer membranes had more phase-separated structures than PUs and PUUs having single soft segments. For gas separation such as O 2/N 2 and CO 2/N 2, the small addition of PDMS into polyether-based PU matrices led to both gas permeabilities and selectivities of O 2/N 2 and CO 2/N 2. This might be that the incorporation of PDMS leads to the phase separation in both hard segment (MDI/BD) and soft segment (polyethers) due to the difference of solubility parameter, and the dispersed PDMS phases serve to produce a more tortuous route for diffusing molecules. While the small addition of polyethers into PDMS-based PUU matrix decreased gas permeabilities, and did not affect the selectivity of O 2/N 2 but increased the selectivity of CO 2/N 2.

Calorimetric Analysis of Vesicular Systems

A number of studies of micellar aggregation in aqueous solutions of ethylene oxide-propylene oxide block copolymers — using high sensitivity differential scanning calorimetry (HSDSC) — are reviewed. The review attempts to show how the calorimetric output can be analysed, using a model fitting procedure, to obtain estimates for various thermodynamic parameters, which characterise the micellization event, as observed by HSDSC. These important parameters include:

Stability-indicating changes in poloxamers: the degradation of ethylene oxide-propylene oxide block copolymers at 25 and 40 °C

Poloxamers are block copolymers of ethylene oxide and propylene oxide that are used within the pharmaceutical industry. The stability of poloxamers 188 and 407 at 25 °C/60% RH and 40 °C/75% RH was studied for 6 months. Poloxamer 407 was stable in both environments, while 188 was degraded at 40 °C/75% RH. For the degraded sample, the formation of formic and acetic acid, and formaldehyde and acetaldehyde was seen with time. Molar mass changes were also seen. Both poloxamers contained an antioxidant, although poloxamer 188 contained less than 407, which explains the difference in stability. The acid formation, pH change, aldehyde formation or change in molar mass can be used as a stability-indicating test for poloxamers. The amount of formed acids and aldehydes indicates that the poloxamer is degraded faster initially at the propylene oxide block.

A novel two-step extraction method with detergent/polymer systems for primary recovery of the fusion protein endoglucanase I–hydrophobin I

Extraction systems for hydrophobically tagged proteins have been developed based on phase separation in aqueous solutions of non-ionic detergents and polymers. The systems have earlier only been applied for separation of membrane proteins. Here, we examine the partitioning and purification of the amphiphilic fusion protein endoglucanase I core–hydrophobin I (EGI core–HFBI) from culture filtrate originating from a Trichoderma reesei fermentation. The micelle extraction system was formed by mixing the non-ionic detergent Triton X-114 or Triton X-100 with the hydroxypropyl starch polymer, Reppal PES100. The detergent/polymer aqueous two-phase systems resulted in both better separation characteristics and increased robustness compared to cloud point extraction in a Triton X-114/water system. Separation and robustness were characterized for the parameters: temperature, protein and salt additions. In the Triton X-114/Reppal PES100 detergent/polymer system EGI core–HFBI strongly partitioned into the micelle-rich phase with a partition coefficient ( K) of 15 and was separated from hydrophilic proteins, which preferably partitioned to the polymer phase. After the primary recovery step, EGI core–HFBI was quantitatively back-extracted ( K EGIcore–HFBI=150, yield=99%) into a water phase. In this second step, ethylene oxide–propylene oxide (EOPO) copolymers were added to the micelle-rich phase and temperature-induced phase separation at 55°C was performed. Total recovery of EGI core–HFBI after the two separation steps was 90% with a volume reduction of six times. For thermolabile proteins, the back-extraction temperature could be decreased to room temperature by using a hydrophobically modified EOPO copolymer, with slightly lower yield. The addition of thermoseparating co-polymer is a novel approach to remove detergent and effectively releases the fusion protein EGI core–HFBI into a water phase.

Cutinase–peptide fusions in thermoseparating aqueous two-phase systems: Prediction of partitioning and enhanced tag efficiency by detergent addition

It is of increasing importance to develop efficient purification methods for recombinant proteins where the number of steps can be minimised. The aim has been to establish a method for predicting the partitioning of the wild-type target protein in an aqueous two-phase system, and with this as basis, develop fusion tags and optimise the phase system for enhanced partitioning of the target protein. The surface of the lipolytic enzyme cutinase from Fusarium solani pisi was investigated with a computer program, Graphical Representation and Analysis of Surface Properties (GRASP). The accessible surface areas for the different amino acid residues were used together with peptide partitioning data to calculate the partition coefficient for the protein. The separation system was composed of a thermoseparating random copolymer of ethylene oxide and propylene oxide, Breox PAG 50A 1000, as top phase forming polymer and a hydroxypropyl starch polymer, Reppal PES 200, as bottom phase polymer. The calculated partition coefficient for the wild-type protein ( K=1.0) agreed reasonably well with the experimentally determined value ( K=0.85). Genetic engineering was used to construct fusion proteins expressed in Saccharomyces cerevisiae based on cutinase and peptide tags containing tryptophan, to enhance the partitioning in aqueous two-phase systems. The partitioning of the cutinase constructs could qualitatively be predicted from peptide partitioning data, i.e. the trends in partitioning could be predicted. A spacer peptide introduced between protein and tag increased the partitioning of the protein towards the ethylene oxide–propylene oxide (EOPO) copolymer top phase. The aqueous two-phase system was modified by addition of detergent to increase the partitioning of the cutinase variants towards the EOPO copolymer phase. Triton and a series of C 12E n detergents selectively increased the partitioning of cutinase constructs with (WP) 4-based tags up to 14 times compared to wild-type cutinase. The protein partition could almost quantitatively be predicted from the peptide partition data.