The activation of the shape-memory effect of nanocomposites (NC) by alternating magnetic fields requires exceeding the switching temperature T-s. Different factors, which can influence this process, have been investigated. The intrinsic properties of magnetic nanoparticles (MNP), their content and distribution in the polymer matrix as well as the heat transport conditions, which are essentially determined by the surface to volume ratio (S/V) of the specimens and their surroundings, influence the achievable temperature in an alternating magnetic field. We used MNP having an iron (II, III) oxide core embedded in amorphous silica, which was homogeneously distributed in a polymer matrix by extrusion moulding. The thermoplastic polymer matrix consists either of an aliphatic polyetherurethane (TFX) for demonstration of the basic correlations between magnetic field and the sample, or of a biodegradable multiblock copolymer (PDC), which is prepared from hard segment forming poly(p-dioxanone) diol (PPDO), switching segment forming poly(epsilon-caprolactone) diol (PCL) and 2,2(4), 4-trimethylhexanediisocyanate (TMDI) as a junction unit. We could demonstrate that a nanoparticle content up to 10 wt% does not decisively change the shape-memory properties or mechanical properties of PDC-based materials.

The paper describes the application of vapor pressure osmometry (VPO) to determine solvent/polymer interaction parameters for various polymer solutions containing high-molecular weight polymers in the semi-diluted concentration range. The theoretical basis for the data evaluation is the Flory–Huggins (FH) model and a virial expansion up to the third virial term. For validation already well characterized polymer/solvent systems poly(vinylpyrrolidone)/water, polysulfone/N,N-dimethylformamide (DMF), and poly(ether sulfone)/DMF were investigated. In the second part interaction parameters of poly(ether imide) (PEI) in solvents with technical relevance for membrane formation (DMF, N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc)) were examined at different concentrations and temperatures. The results document that VPO is a fast and promising method for characterization of semi-diluted polymer solutions containing polymers with higher molecular weight. Results confirm the decrease of solvent power for PEI in the series: NMP>DMAc>DMF.

The work refers to the hydrophilization of microporous poly(ether imide) (PEI) membranes by coating with brominated poly(vinylpyrrolidone) (BrPVP). The PEI microporous membranes were first aminated with poly(ethylene imine) (Pei) and then coated with BrPVP. PVP layer on the membrane prepared from a high molecular weight BrPVP was resistant against washing out with aqueous solutions, which resulted from the stabilization of the gel layer, whereas the layers prepared from unbrominated or low molecular weight BrPVP were not completely stabilized. Separation profiles of resulting membranes can be tailored according to the requirements of application. BrPVP was prepared by the reaction of PVP with bromine or hydrobromic acid. It was possible to prepare BrPVP containing large amounts of bromine, which was rather strongly fixed to the PVP chain. The analysis of the products of the same reaction carried out with 1-ethyl-2-pyrrolidone (EP) (a low molecular weight model of PVP) indicated that the BrPVP comprises addition complexes between HBr molecules and carbonyl groups of PVP. The new PVP coated membranes are promising candidates for the blood contacting applications.

The microwave plasma surface modification of silicone elastomer with allylamine was studied to improve the biocompatibility of the material. An effort was made to clarify the relationships among plasma conditions and surface chemical composition, physical surface properties and biocompatibility of material, as well as the stability of plasma deposited layers. ATR-IR, XPS, Ellipsometry measurements, and contact angle measurements were used to investigate the changes of surface. The stability of plasma-treated silicone surfaces were also studied. The results demonstrated that the temperature and pressure had a strong influence on the chemical composition and structure of surface-deposited layer. The layer was nearly completely crosslinking when the modification was carried out at 60 degrees C. The polymerization speed decreased linearly with temperature. The XPS analysis results showed that the nitrogen element content in the surface layer was very high, especially under low pressure. The nitrogen/carbon ratio in the layer even greatly surpassed that of the allylamine monomer. The wettability of the silicone surface was greatly improved after plasma modification, and increased with the quantities of amine groups. The plasma-treated surfaces have good storage stability in air up to 3 months. The wettability of the surfaces decreased incipiently and then it dramatically increased with further time. The human skin fibroblasts were used to evaluate biocompatibility of plasma-treated silicone elastomer. The surface biocompatibility was greatly improved after modification; human skin fibroblasts adhered quickly and grew well on the modified silicone surface.

The work describes the functionalization of microporous poly(ether imide) membranes with ultrafiltration separation profile by degradative functionalization using a two-step treatment process, which leads to strongly aminated membranes with microfiltration properties. Membranes with different morphology and ultrafiltration separation profile were prepared. In the first step, the pore system was opened by treatment with diethylenetriamine (DETA) which was followed by a treatment with high molecular poly(ethylene imine) to increase the amount of amine groups. Results verify that macrovoidal structures are more beneficial than sponge-like structures because of their strongly opened pores while only a small reduction in membrane thickness occurred. The separation properties of the virgin membrane have only a marginal influence on the pore opening process because of the leveling off the separation properties after a short treatment time. The number of covalently bound amine functions could be strongly increased by a second step functionalization process using a high-molar volume polyamine as a modifier which indicates the presence of residual imide groups of the basic polymer after the primary DETA treatment. Moreover the prepared membranes are suited for steam sterilization. These characteristics suggest a beneficial application in adsorptive separation processes.

The duomodule integrates two kinds of serially connected hollow fiber filters in a common module housing. The inner compartments of both filters are interlocked by a stable connection in which a throttle valve is integrated. The connected outer compartments of the filters are filled with an incompressible fluid. At a liquid flow in the inner compartment (primary circulation), a secondary circulation is generated due to a pressure drop between the filters. Filtration from the inner compartment to the outer compartments is initiated in the first filter, whereas refiltration takes place in the common outer compartment to the inner compartment in the second filter as a consequence of a transmembrane pressure reversal. In this paper, different duomodule arrangements are used for the fractionation of an aqueous dextran solution mixture to detect the duomodule separation ability and efficiency and to optimize the module construction. The fractionation ability and efficiency are related to the membrane characteristics. The results of the fractionation experiments demonstrate the separation function of the equipment. In the refiltration step, the transport direction goes from the outer to the inner membrane surface; therefore, an internal concentration polarization in the membrane wall can change the permeability and the separation behavior of the refiltration membrane. Accordingly, only symmetrically structured membranes or outside active refiltration membranes realize a desirable high fractionation ability and efficiency.

Remote microwave plasma polymerization of acrylic acid for the formation of layers containing carboxylic acid groups on poly(ethylene terephthalate) track-etched membranes is investigated. The influence of deposition parameters — microwave power, pulsed or continuous wave and pressure — on film formation is examined. The content of carboxylic acid groups is determined by fluorescence labeling with thionine acetate and X-ray photoelectron spectroscopy, the change of pore-size distribution by porometry and water permeation experiments. The pores were covered regularly, and the pore size could be adjusted. Layers deposited at 200 W and 90 Pa contained a concentration of carboxylic acid groups of 0.9 mmol cm−3.

The preparation of hollow-fiber membranes with high asymmetric morphology by a wet spinning process by phase inversion of polymer solutions with a nonsolvent medium is normally connected with the formation of a relatively dense unwelcome skin. One possibility to eliminate this disadvantage is a phase inversion process with gel/sol/gel-treatment, whose physicochemical peculiarities are descibed in this paper. In the gel/sol/gel-treatment an initially wet hollow-fiber membrane is contacted with a solvent and subsequently with a nonsolvent again. Such a technology causes a second phase inversion at the outer surface of the hollow-fiber membrane. Results about parameters influencing the gel/sol/gel-process are presented as an illustration for the treatment of polyacrylonitrile hollow-fiber membranes with a special structure. In conclusion, first ideas of the mechanism of this process are formulated.

Polyacrylonitrile membranes with different separation ranges are prepared and characterized by gel permeation chromatography. The determination of the pore size distribution of the ultrafiltration flat membrane (upper ultrafiltration range) and of the microfiltration hollow fiber membrane (lower microfiltration range) is affected by different measuring procedures. A comparison of the parameters of separation performance is obtained by making use of aqueous poly(ethylene glycol) (PEG) mixtures with broad molecular weight distribution, or the application of single PEG test substances is performed. The obtained results are discussed in connection with the separation range of membranes and the molecular weight of test solutions.

Remarkable highly porous structures are formed by the coagulation of incompatible phase-forming polymer blend solutions. The effect of an added polymer on the porosity of the primary layer is studied. Investigations of the permeability of membranes prepared by different procedures revealed that only in flat membranes prepared on a solid support an elevated porosity of the primary coagulated layer could be observed. A mechanism of pore formation in this special case is suggested.

Highly porous coagulated structures are formed by coagulating incompatible phase-forming polymer blend solutions. The maximum of the pore volume in the so formed shaped bodies is essentially predetermined by the volume of the dispersed phase owned by the solution of the added polymer in the polymer blend solution. Taken as an example, the blend system PAN/SAN/DMF revealed this principle of structure formation also to be valid for the general system polymer(A)/copolymer (AB)/solvent by taking into consideration the relations of solvation in the mixed solutions and variations of the compatibility relations, too.

Acta PolymericaVolume 42, Issue 7 p. 340-342 Short Communication Grobporige hohlmembranen aus acrylnitrilpolymeren W. Albrecht, W. Albrecht Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorP. Klug, P. Klug Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorW. Makschin, W. Makschin Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorT. Weigel, T. Weigel Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorV. Gröbe, V. Gröbe Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorD. Paul, D. Paul Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this author W. Albrecht, W. Albrecht Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorP. Klug, P. Klug Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorW. Makschin, W. Makschin Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorT. Weigel, T. Weigel Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorV. Gröbe, V. Gröbe Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this authorD. Paul, D. Paul Institut für Polymerenchemie „Erich Correns”︁, O-1530 TeltowSearch for more papers by this author First published: July 1991 https://doi.org/10.1002/actp.1991.010420714Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume42, Issue7July 1991Pages 340-342 RelatedInformation

Polyacrylonitrile membranes are prepared using three different membrane preparation principles. Characterization of the structure of the skin layer is carried out in more detail by parameters of separation curves and their pore size distribution function, the former being based on a logarithmic normal distribution. Under constant conditions of measurement, comparing considerations are reflected about the structure of the separating active layer of PAN bicomponent membranes and two differently prepared PAN monocomponent membranes. The parameters of the separation curves and pore size distributions are discussed.

The effect of the ratio of the thickness of the polymer solution layers on the structure formation at the inner layer of bicomponent membranes prepared by means of a bicomponent slit die is studied. Basing on the data of mass transfer through the membrane and REM investigations a conception of the coagulation process is suggested. The process is quantitatively described by the second Fick's law. Apparent diffusion coefficients are calculated. The structure transition point of the system CA/DMF-PUR/DMF has been derived from the results and was experimentally confirmed.

Using the so-called bicomponent principle, which consists in the preparation of a compound film of two polymer solutions followed by separation of this bicomponent compound in two bicomponent membranes, polymer membranes with new structures having a high degree of asymmetry could be made. A variant of this principle is suggested where the bicomponent slit die dips into the liquid coagulation medium. The effect of the coagulation conditions, especially of the composition of the coagulation medium, on the structure and the separation properties of the resulting membranes is discussed with the examples of poly(acrylonitrile), cellulose-2.5-acetate, and polyurethane.

Acta PolymericaVolume 40, Issue 7 p. 485-486 Short Communication Influence of gases dissolved in polymer solutions on the structure of solids formed thereof V. Gröbe, V. Gröbe Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this authorW. Makschin, W. Makschin Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this authorW. Albrecht, W. Albrecht Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this authorP. Klug, P. Klug Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this authorTh. Weigel, Th. Weigel Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this author V. Gröbe, V. Gröbe Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this authorW. Makschin, W. Makschin Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this authorW. Albrecht, W. Albrecht Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this authorP. Klug, P. Klug Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this authorTh. Weigel, Th. Weigel Academy of Sciences of the GDR, Institute of Polymer Chemistry „Erich Correns”︁, Teltow, GDR-1530, German Democratic RepublicSearch for more papers by this author First published: July 1989 https://doi.org/10.1002/actp.1989.010400717Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume40, Issue7July 1989Pages 485-486 RelatedInformation

At the coagulation of polymer blend solutions of a lot of polymer couples precipitation structures with a remarkable system of voids are generated, which show good stability at drying. The conditions for the formation of the increased porosity are investigated. High porosity is realised when the polymer blends are separated in two phases in the solute state and when the main polymer has a high rate of coagulation. A mechanism of the formation of voids is suggested which is based on the existence of two solidification front lines.

Acta PolymericaVolume 40, Issue 2 p. 137-137 Kurze Mitteilungen Einfluß der Alterung von Polyacrylnitril-Lösungen auf die Eigenschaften daraus hergestellter Membranen V. Gröbe, V. Gröbe Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this authorW. Makschin, W. Makschin Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this authorW. Albrecht, W. Albrecht Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this authorP. Klug, P. Klug Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this authorTh. Weigel, Th. Weigel Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this author V. Gröbe, V. Gröbe Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this authorW. Makschin, W. Makschin Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this authorW. Albrecht, W. Albrecht Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this authorP. Klug, P. Klug Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this authorTh. Weigel, Th. Weigel Akademie der Wissenschaften der DDR, Institut für Polymerenchemie „Erich Correns”︁, Teltow-Seehof, DDR-1530Search for more papers by this author First published: February 1989 https://doi.org/10.1002/actp.1989.010400217Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume40, Issue2February 1989Pages 137-137 RelatedInformation

At the coagulation of polymer blend solutions highly porous structures are formed. This paper presents a mathematical formalism for the prediction of the expected pore volume and results on the influence of concentration, kind and quantity of the added polymer. The experimental results are in good agreement with calculated values and thus confirm our concept of the mechanism of pore formation by coagulation of mixtures of polymer solutions.