Suitable Solvent System Research Articles

Solvent strength of aqueous phase for two typical biphasic solvent systems in high-speed countercurrent chromatography

In the present work, influence of solvent strength of aqueous phase for two frequently-used biphasic solvent system in partition coefficient (K) of selected solutes were mainly studied, and a new method for selection of biphasic solvent system was proposed for high-speed countercurrent chromatographic separations. Solvent strength was referred to the typical theory that was deeply investigated in conventional reversed-phase liquid chromatography. Experimental results showed that a linear relationship between log(K) of solutes and apparent content of methanol in biphasic solvent system was found for the biphasic solvent system hexane-ethyl acetate-methanol-water (HEMWat), which was consistent with the relationship between real content and apparent content of methanol in this system. Meanwhile, a quadratic relationship was found between log(K) of solutes and apparent content of methanol in biphasic solvent system chloroform-methanol-water (ChMWat), in which it was found that the relationship between real content and apparent content of methanol in this system was also quadratic. In addition, a visual and simple method was proposed to select a suitable biphasic solvent system for separation of target compounds by high-speed countercurrent chromatography with isocratic elution, which saves a lot of manpower and material resources in order to find a suitable two-solvent system. An optimal biphasic solvent system for isolation of several tested compounds by high-speed countercurrent chromatography was easily obtained using our proposed method.

Applications of the Hansen solubility parameter for cellulose

Based on the solubility parameter theory, the Hansen solubility parameters of various solvents were calculated and compared to predict the solubility of cellulose in various solvents, which illustrates the feasibility of Hansen solubility parameters to predict the solubility of cellulose in solvents. This paper aims to make a more accurate prediction in advance when finding suitable cellulose solvent system, and then to reduce the burden of cellulose solvent selection.

Role of three-phase solvent system in the counter-current chromatography.

In counter-current chromatography, the separation efficiency greatly depends on the partitioning ability of the separated substance between the stationary phase and the mobile phase. Partitioning ability is mainly represented by the parameter partition coefficient which is one of the important parameters to evaluate the separation effect of counter-current chromatography. The scope of the partition coefficient value mainly depends on the solvent system. A suitable solvent system election is, therefore, a critical role in the separation of counter-current chromatography. The existing solvent systems that are widely used are mainly two-phase solvent systems. It is difficult to decide on an appropriate solvent system for the separation of compounds with a wide polarity range, which promotes the development of the three-phase solvent system in counter-current chromatography. This review mainly described the origin, development history of three-phase solvent system, summarized the volume ratios and volume fractions of the upper, middle, and lower phases of nearly 50 three-phase solvent systems, their advantages, and disadvantages in counter-current chromatography. In addition, the challenges and future perspectives on three-phase solvent systems in counter-current chromatography also are discussed in this review.

Prodigiosin purification from Serratia marcescens M10 and its antitumor activities

Prodigiosin (Pg) is a bright red pigment, which is produced by gram negative and gram positive bacteria including Serratia marcescens, Hahella chejuensis, Vibrio psychroerythrus, Streptomyces coelicolor and many other marine bacteria such as Pseudomonas sp., Vibrio sp. Pg induces apoptosis in different kinds of cancer cells with low toxicity on normal cells. In this study, we purified Pg from solid fermentation of S. marcescens M10 strain and assessed its anticancer activity in tumorized mice. The results showed that Pg was purified by running through a silicagel 60 column with a suitable solvent system of n-hexane:toluene at the rate of 1:1 (v/v) combined with toluene:ethyl acetate at the rate of 9:1 (v/v). TLC plate was used to test the presence of active substances with separation solvent n-hexane:ethyl acetate ratio of 1:1 (v/v). The purity of fractions tested by high performance liquid chromatography method showed as 98%. Purified fractions also showed promising anti-tumor activity in Lewis lung carcinoma induced tumors in BALB/c mice. The tumor volumes in Pg treated groups decreased by 34.18% after 28 days of administration.

Synthesis, crystal structure, and density functional theory study of a new compound 4‐(2‐chlorobenzyl)‐1‐(5‐fluoro‐2‐hydroxy‐3‐(thiomorpholinomethyl)phenyl [1,2,4]triazolo[4,3‐a]quinazolin‐5(4H)‐one

AbstractIn this paper, a novel SHP244 derivative 4‐(2‐chlorobenzyl)‐1‐ (5‐fluoro‐2‐hydroxy‐3‐ [thiomorph‐olinomethyl] phenyl)‐ [1,2,4]triazolo [4,3‐a] quinazolin‐5(4H)‐one was synthesized through five steps. The single crystals were grown in a suitable solvent system (dichloromethane and methanol). Its structure was confirmed by 1H NMR, 13C NMR spectroscopy, ESI‐MS, m/z: 534.12[M‐H] (MS), FT‐IR, and X‐ray single crystal diffraction. The crystal structure of the title compound was optimized by density functional theory (DFT) calculation. The crystal structure after X‐ray single crystal diffraction was compared with the structure optimized by DFT calculation, and the result shows that the two structures are consistent. In order to explore certain physical and chemical properties, the frontier molecular orbital and molecular electrostatic potential of the title compound were analyzed. In addition, the docking of the title compound to the target protein was studied to understand the docking effect of the compound with the target protein.

Isolation of sesquiterpenoids from Matricaria chamomilla by means of solvent\xa0assisted flavor evaporation and centrifugal partition chromatography

The (semi)volatile fraction of Matricaria chamomilla L., an annual herbal plant from the family of Asteraceae, contains high quantities of sesquiterpenes and sesquiterpenoids. A method was developed to achieve isolation and separation of these compounds, using a combination of solvent assisted flavor evaporation (SAFE) and solid support-free liquid-liquid chromatography. The biphasic liquid solvent system n-heptane/ethyl acetate/methanol/water, 5/2/5/2 v/v/v/v (Arizona S) was elaborated as a suitable solvent system for the simultaneous separation of the target compounds. The lab-scale liquid-liquid chromatography separation performed in a countercurrent chromatography (CCC) column was successfully transferred to a semi-preparative centrifugal partition chromatography (CPC) column, which enabled the isolation of artemisia ketone, artemisia alcohol, α-bisabolone oxide A, and (E)-en-yn-dicycloether. α-Bisabolol oxide A and (Z)-en-yn-dicycloether co-eluted, but were successfully separated by subsequent size-exclusion chromatography (SEC). Similarly, spathulenol and α-bisabolol oxide B were obtained as a mixture, and were separated by means of column chromatography using silica gel as stationary phase. The isolated compounds were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gas chromatography–mass spectrometry (GC-MS).Graphical abstract

Total content of polyphenols, flavonoids, rutin, and antioxidant activity of sea buckthorn juice

The antioxidant activity, total polyphenol content (TPC), and total flavonoids content (TFC) of sea buckthorn juice was analyzed with electron paramagnetic resonance (EPR) and ultraviolet-visible (UV-VIS) in ethanol, methanol, and acetone extracts. The choice of a suitable solvent system is necessary so as not to skew the results. Undiluted juice of sea buckthorn berries is not suitable for the mentioned analyzes. Sea buckthorn juices were evaporated under vacuum until completely dry and then dissolved in 100% methanol, 96% ethanol, 70% ethanol, and 50% acetone. The 70% ethanol extract of sea buckthorn juice had an average of 1.3- and 1.6-times greater TPC and TFC values than other extracts, respectively. The 70% ethanol extract of juice contained 29 mg gallic acid equivalents (GAE)/g dw and 4 mg catechin equivalents (CE)/g dw. The results of the antioxidant activity of the extracts determined by EPR spectroscopy had an error rate ~ 2.5 times lower than the UV-VIS analysis. The highest antioxidant activity (123 mmol of Trolox equivalents/kg extract) was determined with EPR and ABTS radical in the 70% ethanol extract. This method correlated well with the TFC levels.

Influence of extraction methods and solvent system on the chemical composition and antioxidant activity of Centella asiatica L. leaves

Abstract Centella asiatica is a valuable medicinal herb widely used in traditional Indian and Chinese system of medicine. However, a suitable extraction method and solvent system to optimize extraction of bioactive compounds and antioxidant capacity in C. asiatica is still lacking. Therefore, the present work was undertaken to screen out an efficient extraction technique on antioxidant capacity and recovery of bioactive compounds in C. asiatica using modern extraction methods (ultrasound-assisted extraction (USAE), microwave-assisted extraction (MAE) and conventional methods like heat reflux extraction (HRE) and maceration (MAC) with methanol, ethanol, acetonitrile, water, 50% aqueous methanol, 50% aqueous ethanol as extracting solvents. Eight major compounds were identified and quantified using a validated High-performance liquid chromatography with diode-array (HPLC-DAD) method. Method validation was done in terms of accuracy, precision, LOD and LOQ. Antioxidant activity of the extracts was evaluated by using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS assay). MAE using methanol was found to be the most effective technique as it showed highest recovery of the eight bioactive compounds viz chlorogenic acid (0.18%), rutin (0.11%), quercetin (0.02%), kaempferol (0.10%), madecassoside (0.76%), asiaticoside (2.66%), madecassic acid (0.32%) and asiatic acid (1.98%) and maximum DPPH (IC50 45.17 μg/ml) and ABTS (IC50 26.38 μg/ml) values were achieved as compared to other conventional methods.

Rapid enrichment and separation of two novel minor phenols from Malus hupehensis utilizing liquid-liquid extraction with three-phase solvent system and high-speed counter-current chromatography based on the polarity parameter.

For a rapid enrichment and separation of minor components from Malus hupehensis, the selection of suitable solvent system is the great challenge for liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography. According to the concept of "like dissolves like," the similarity of the average polarity between solvent system and target compounds was the significant characteristic of liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography separation. The polarity parameter model provides a way to calculate the polarity of unknown compounds. Under the guidance of the polarity, an efficient enrichment and separation approach was established through liquid-liquid extraction and high-speed counter-current chromatography with solvent systems composed of n-hexane-ethyl acetate-acetonitrile-water (5:3:5:7, v/v), n-hexane-ethyl acetate-methanol-water (1:2:1:2, v/v), respectively. Thus, the total content of minor compounds was increased from 2.6% to 17.2%, and two novel compounds (6´´-O-coumaroyl-2´-O-glucopyranosylphloretin and 3´´´-methoxy-6´´-O-feruloy-2´-glucopyranosylphloretin) were obtained. The discovery of the new dihydrochalcones expanded the structural diversity of compounds produced by the genus Malus. The experimental results demonstrated that compound polarity can be described by the polarity parameter model and is an important reference for investigating optimum solvent systems for liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography.

Development of a gel permeation chromatography method for analysing cellulose nitrate in museums.

This article describes the development of a suitable Gel Permeation Chromatography method for cellulose nitrate plasticised with camphor (celluloid) found in cultural heritage. Current sample preparation and dissolution methods, apart from focusing on native, nonderivatised cellulose, require long preparation times, and often employ solvents that induce degradation. This study aims to develop a systematic method for sample preparation of cellulose nitrate that uses the least sample amount possible, is nondegrading, and can be applied on differently aged samples. This is investigated through identification of a suitable solvent system and a statistically designed experiment testing the critical variables affecting the analysis, namely sample condition, sample, and salt concentration (lithium chloride) in N,N-dimethylacetamide. The use of 0.1% sample was inadequate for analysis because it did not fully dissolve in any salt concentration, while the 0.3% negatively impacted the analysis with its high molecular weight distributions. The 0.2% cellulose nitrate in a solution of 0.5% lithium chloride in N,N-dimethylacetamide offered the most consistent and repeatable molecular weight data. This method miniaturised the sample as much as possible and is suitable for museum objects in various ageing conditions.

Extraction and separation of flavonoids from Malus hupehensis using high-speed countercurrent chromatography based on deep eutectic solvent

In the present experiment, a green and highly efficient extraction method for flavonoids established on deep eutectic solvents (DESs) was investigated by using the response surface methodology. The DES-based high-speed countercurrent chromatography (HSCCC) solvent systems were developed for the separation of high purity compounds from the DES extract of Malus hupehensis for the first time. Under the optimal conditions (liquid-to-solid ratio of 26.3 mL/g, water content of 25.5%, and extraction temperature of 77.5°C), the yield of flavonoids was 15.3 ± 0.1%, which was superior to that of the methanol extraction method. In accordance with the physical property of DES-based HSCCC solvent systems and K values of target compounds, DES-based HSCCC solvent systems composed of choline chloride/glucose-water-ethyl acetate (ChCl/Glu-H2O-EAC, 1:1:2, v/v) was selected for the HSCCC separation. Thus, five flavonoids (two novel compounds 1-2, 6´´-O-coumaroyl-2´-O-glucopyranosylphloretin and 3´´´-methoxy-6´´-O-feruloy-2´-O-glucopyranosylphloretin; three know compounds 3-5, namely, avicularin, phloridzin, and sieboldin) were efficiently separated from Malus hupehensis. DESs are the environment friendly and highly efficient solvents as the components of extraction solvent and HSCCC solvent system, and can be re-utilized many times. However, ethyl acetate can be soluble with a few hydrogen bond donors, such as urea, carboxylic acid and polyol, through the shake flask test. It is the great difficulty for the efficient and rapid separation of target compounds from the DESs extract because of the DESs residual in the HSCCC fractions. ChCl and Glu are the great choices of DESs without this problem. In addition, K values increased with the increase of the molar ratio of ChCl/Glu and the content of water, which could effectively guide us to choose the suitable DES-based HSCCC solvent system. The twice HSCCC separation results indicated that DES was the valuable and green solvent for the HSCCC separation of pure compounds from the extract for the first time, and showed the recycle superiority of DES-based HSCCC solvent system.

Trans(Cl)-2,2′-bipyridinedicarbonyldichlororuthenium(II) complex catalyzed oxidation of olefins, aryl hydrocarbons and alcohols in homogeneous phase

Catalytic oxidation of organic substrates has wide applications in chemical industries due to which huge extensive research work is continuously going on throughout the world. Present study reports efficacious use of Trans (Cl)-2,2′-bipyridinedicarbonyldichlororuthenium(II) complex catalyzed oxidation of internal and terminal olefins, aryl hydrocarbons and alcohols. CH2Cl2–C2H5OH (6:4) was suitable solvent system for these oxidation reactions. The normal pressure oxidation reaction has been carried out at 1 ​atm. Pressure of oxygen and at 300C. The high pressure oxidation reaction was done at 4.48 ​× ​103 KNm3 pressure of oxygen and at 600C. No diminished catalytic activity was observed while checking the recyclability of catalyst up to 6–8 catalytic runs. Catalytic activity was also investigated using tert-butyl hydroperoxide as oxidant inspite of di-oxygen. Effect of different parameters on the rate of oxidation was also studied i.e. extra ligand, temperature, solvents, acids and bases. Kinetic studies have been done and on the basis of kinetics, the mechanism is proposed.

Phytochemical and antioxidant evaluation of cassia sieberiana D.C. stem bark extracts

Cassia sieberiana D.C. belongs to the Fabaceae family and it is used ethnomedically in the management of cancer, diabetes and other diseases. There is a growing concern about the scourge of diseases caused by excessive free radicals in the body and lack of standardization of medicinal herbal products. Therefore, this research is aimed at evaluating the phytochemical and free radical scavenging activities of the plant extracts with the view to identify the chemical constituents and antioxidant properties of the extracts. The powdered stem bark was evaluated for its pharmacognostic profiles and then extracted successively with the aid of Soxhlet extractor using n-hexane, ethyl acetate and methanol. The extracts obtained were concentrated using rotary evaporator and the percentage yields of the extracts were determined. The extracts were screened for their phytochemical constituents using standard protocols. The thin layer chromatography (TLC) profiles of the resulting extracts were determined using suitable solvent systems and the retention factor (Rf) values of separated spots of compounds were calculated. The total phenolic content of the ethyl acetate and methanol extracts were measured using Folin-Ciocalteu reagent and gallic acid was used as standard. The antioxidant (free radical scavenging) activity of the extracts were measured using DPPH (2, 2-diphenyl-1- picryl hydrazyl) and ascorbic acid was used as standard. The results were expressed in terms of percentage inhibition. The percentage yields of the extracts were: 0.52 %, 6.58 % and 10.52 % respectively for n-hexane, ethyl acetate and methanol. The preliminary phytochemical screening of the extracts revealed the presence of tannins, cardiac glycosides, saponins, flavonoids and triterpenoid/steroids. Also, the total phenolic contents were found to 7.64 mg and 2.97 mg gallic acid equivalents for ethyl acetate and methanolic extract respectively. The free radical scavenging activity of the extracts revealed higher activity in the ethyl acetate extract. The results indicated that the extracts contain phenolic compounds which may be responsible for the antioxidant activity.

Preparation of brazilein from Caesalpinia sappan by high performance countercurrent chromatography

Brazilein is among the main chemical constituents of Caesalpinia sappan. It has diverse pharmacological activities. Modern pharmacological studies have shown that the compound has antitumor, anti-inflammatory, antibacterial, antioxidant, immunomodulatory, and other pharmacological activities. Brazilein is often used as a stain in various industries. The separation of brazilein by traditional column chromatography will not only result in contamination of the chromatographic column materials, but also lead to loss of the active ingredient. Countercurrent chromatography is an advanced liquid-liquid chromatographic separation technique. It has been widely used for natural product separation and isolation as it offers several advantages, such as low solvent consumption, a highly selective solvent system, and high recoveries. Typical countercurrent chromatography techniques include centrifugal partition chromatography (CPC), high-speed countercurrent chromatography (HSCCC), and high performance countercurrent chromatography (HPCCC). It is well known that choosing a suitable solvent system is vital in countercurrent separation. Therefore, two methods were introduced for choosing a suitable solvent system. One is the generally useful estimation of solvent systems (GUESS) method, which employs thin-layer chromatography (TLC) to identify a suitable solvent system with minimal labor for the rapid purification of target compounds, and another is the Shake-Flash method. The solvent system could be determined by observing the distribution of the sample in the upper and lower phases. Two kinds of solvent systems were screened using the TLC-GUESS and Shake-Flash methods, and tested through the analysis mode of the HPCCC instrument. The results showed that chloroform-methanol-water (4:3:2, v/v/v) was the optimal solvent system for HPCCC separation. A total of 15.2 mg of brazilein and 5.7 mg of caesappanin C were obtained from an ethyl acetate extract with high purities (95.6% and 89.0%, analyzed by HPLC) in one step using the preparation mode of HPCCC, the reversed-phase liquid chromatography mode with the apparatus rotated at 1600 r/min, a flow rate of 10 mL/min, separation temperature of 25℃, and detection wavelength of 285 nm. Their structures were determined by spectroscopic and spectrometric analyses. Brazilein stained the solid packing material in the column and was difficult to elute. The results showed that the use of HPCCC for the separation of brazilein can not only prevent the loss of target active ingredients in Caesalpinia sappan, but also shorten the separation and purification times and improve the operating efficiency. Therefore, HPCCC can be used for the separation and preparation of other pigment compounds in Caesalpinia sappan and other dye plants.

Separation of six antioxidants from Hypsizygus marmoreus by high-speed countercurrent chromatography utilizing an approach based upon the polarity parameter model

For a successful high-speed countercurrent chromatography (HSCCC) separation of multiple components, the suitable solvent system selection is a critical operation. Despite the difference in separation mechanism between HSCCC and HPLC, K values of compounds in the solvent system and the retention factor of compounds in HPLC were connected with polarity, and the polarity mainly depended on the structure and chemical properties of compounds. On the basis of the concept of “like dissolves like”, the average polarity of the solvent system is equal to the average polarity of multiple components at the “sweet point” log K = 0. The result of theoretical deduction showed a negative linear correlation between the polarity of each component and the logarithm of the gradient range of the organic phase. Therefore, the average polarity of unknown multiple components could be obtained through the polarity parameter model established in the HPLC analysis. The suitable solvent system composed of n-hexane–ethyl acetate–methanol–water (8:3:8:1, v/v) was selected through the average polarity of multi-components combining K values of the enriched samples. In the context of bioassay, an efficient HSCCC separation procedure was established, and two groups of analogue benzaldehyde derivatives (four main antioxidants, namely, isodihydroauroglaucin, isoaspergin, isotetrahydro-auroglaucin, and flavoglaucin; two minor antioxidants, namely, 6′-oxo-chaetopyranin and chaetopyranin) were obtained from Hypsizygus marmoreus. The predicted polarity values of multi-components were sufficient to meet the HSCCC experimental requirements. The HPLC analysis of reference compounds and multi-components showed a significant consistency with different chromatographic columns. Therefore, the polarity parameter model established in the HPLC analysis was a simple, rapid, and helpful tool for looking an appropriate solvent system, which was a forwarding step for the HSCCC separation of multiple components.

Magnetic Properties of Metal Clusters Coordinated with (Nitronyl Nitroxide)‐Substituted Amidinate Ligands

AbstractWe prepared dicopper, disilver, and tetragold clusters ligated with (nitronyl nitroxide)‐substituted amidinate (NN‐amidinate). NN‐substituted amidine was prepared from N,N′‐diphenylcarbodiimide via a nucleophilic reaction with nitronyl nitroxide as a radical anion. The NN‐amidinate ligand was generated by treatment with an appropriate base, and subsequent addition of copper(I), silver(I), or gold(I) sources gave the respective metal cluster systems of Cu2‐(NN‐amidinate)2, Ag2‐(NN‐amidinate)2, or Au4‐(NN‐amidinate)4. These radical‐metal clusters exhibited excellent stability, even in solution under aerated conditions, making them easy to handle. Single crystals were obtained by recrystallization from suitable solvent systems. The spin structures of the cluster systems were investigated by ESR spectroscopy and magnetic susceptibility measurements, which indicated the existence of weak intramolecular, spin‐spin interactions between the NN moieties.

Separation of five flavonoids with similar polarity from Caragana korshinskii Kom. by preparative high speed counter‐current chromatography with recycling and heart cut mode

Five flavonoids with similar polarity were obtained from Caragana korshinskii Kom. by preparative high speed counter-current chromatography. Due to their similar polarity, it is difficult to select a suitable solvent system for one-step separation. Three fractions including one pure compound were only obtained with a relatively suitable solvent system of ethyl acetate: n-butanol:water (0.5% glacial acetic acid) (4:6:10, v:v:v). In order to improve the separation efficiency, recycling and heart cut modes were introduced. As a result, two flavonoids with separation factor value at 1.13 and the other two with separation factor value at 1.20 were successfully separated. Finally, five flavonoids with purity higher than 98% were obtained. Fortunately, a new compound named myricetin 3'-methyl ether 3-O-glucoside-7-O-rhamnoside was obtained. The results indicated that the recycling combined with heart-cut mode could be effective for the preparation of natural compounds with similar polarity.

Method Development and Validation of UV Spectrophotometric Method for the Quantitative Estimation of Curcumin in Simulated Nasal Fluid.

Curcumin is a polyphenolic compound with numerous therapeutic activities. There is no validated method available for the quantitative estimation of curcumin in simulated nasal fluid. The aim of present investigation was to develop a simple and precise UV visible spectrophotometric method for estimation of pure form of curcumin in simulated nasal fluid. Suitable solvent system was selected by estimation of curcumin at UV maxima of 421nm in simulated nasal fluid with two surfactants (tween 80 and sodium lauryl sulphate). The double beam UV visible spectrophotometer was used for measurement of absorption. The selected solvent system was further validated according to guidelines of international conference on harmonization (ICH), the analytical parameter like linearity, precision and accuracy etc. were studied. Simulated nasal fluid with tween 80 at 1% concentration satisfied all the conditions relative to Peak quality at the stated wavelength. In developed method, curcumin was found to be linear over selected concentration range of 5 to 60µg/ml with a correlation coefficient of 0.998. The accuracy was found to be in range of 99.51 -100.223%.The precision was found to be less than 2 in terms of % RSD. The LOD & LOQ were 0.3657 & 1.109 respectively. The proposed method was found to be simple, sensitive and precise. The most important this method can be used for routine quality control analysis of curcumin with accuracy.

Development of Polyoxymethylene Particles via the Solution-Dissolution Process and Application to the Powder Bed Fusion of Polymers.

In this study, the development of a polyoxymethylene (POM) feedstock material for the powder bed fusion (PBF) of polymers is outlined. POM particles are obtained via liquid-liquid phase separation (LLPS) and precipitation, also known as the solution-dissolution process. In order to identify suitable POM solvent systems for LLPS and precipitation, in the first step, a solvent screening based on solubility parameters was performed, and acetophenone and triacetin were identified as the most promising suitable moderate solvents for POM. Cloud point curves were measured for both solvents to derive suitable temperature profiles and polymer concentrations for the solution-dissolution process. In the next step, important process parameters, namely POM concentration and stirring conditions, were studied to elucidate their effect on the product’s properties. The product particles obtained from both aforementioned solvents were characterized with regard to their morphology and size distribution, as well as their thermal properties (cf. the PBF processing window) and compared to a cryo-milled POM PBF feedstock. Both solvents allowed for precipitation of POM particles of an appropriate size distribution for PBF for polymer concentrations of at least up to 20 wt.%. Finally, a larger powder batch for application in the PBF process was produced by precipitation from the preferred solvent acetophenone. This POM powder was further analyzed concerning its flowability, Hausner ratio, and mass-specific surface area. Finally, test specimens, namely a complex gyroid body and a detailed ornament, were successfully manufactured from this feedstock powder showing appropriate bulk solid and thermal properties to demonstrate PBF processability. In summary, a processable and suitable POM PBF feedstock could be developed based on the non-mechanical solution dissolution process, which, to the authors’ best knowledge, has not been reported in previous studies.

Polyethyleneoxide‐b‐poly(isopropyl methacrylate) diblock copolymers as novel material for ultrafiltration membranes

ABSTRACTAmphiphilic polyethyleneoxide‐b‐poly(isopropyl methacrylate) (PEO‐b‐PiPMA) diblock copolymers (BCP) with different molar masses are synthesized via atom transfer radical polymerization (ATRP). For that functionalized PEO monomethyl ether with two different molar masses, 10 and 20 kDa, are used as macroinitiator to obtain BCP in a molar mass range relevant for membrane fabrication. The BCP are used in the nonsolvent induced phase separation (NIPS) with the aim to obtain isoporous ultrafiltration membranes due to combination with its self‐assembling properties (SNIPS). In various experiments, a strong effect of PEO homopolymer (hPEO) on the membrane formation process can be proven in which fractions of BCP with low molar mass might also play a role. These impurities are left in the BCP after ATRP due to incomplete purification. Under specific conditions, they induce formation of void‐like superstructures on the membrane surface and in the cross section by a templating mechanism. Probably, large compound micelles play a key role in this scenario hindering the favored SNIPS process. The superstructure formation can be avoided by extensive purification of the BCP via dialysis or extraction. From the purified polymers, self‐supported ultrafiltration membranes with an integrated hydrophilic component are successfully fabricated. Although they do not lead to isoporous surfaces after semiempirical determination of suitable solvent systems for the SNIPS process, there are convincing indications that the trade‐off relation between selectivity and permeability can be overcome. © 2020 The Authors. Journal of Polymer Science published by Wiley Periodicals, Inc. , 2020, 58, 2561–2574