Judicial Nominee Announced for Holyoke Courts

Fabrication of evaporation-induced self-assembled structures on easily accessible surfaces is an established strategy, while achieving such microphase-separated structures in compact geometries has been a long-standing goal. The requirement of comparatively less concentrated block copolymer (BCP) solution to pass through the compact geometries significantly reduces the stimulations required for self-assembly. The high polymer relaxation rates and decreased thermodynamic driving forces, as well as high capillary suction of dilute solutions in the porous substrates, complicates the BCP self-assembly and fabrication of the uniform coated layer, respectively. In this study, highly permeable robust poly(ether sulfone) hollow fiber membranes (PES HFM) with an inner diameter of approximately 1 mm are selected as compact geometries, and the isoporous structures are developed on top of ≤10 μm thin coated layer. This fabrication process introduces a technologically favored inside-out configuration for isoporous composite HFM with large bore diameters

Synthesis, Transfer, and Gas Separation Characteristics of MOF-Templated Polymer Membranes

This paper discusses the potential of polymer networks, templated by crystalline metal–organic framework (MOF), as novel selective layer material in thin film composite membranes. The ability to create mechanically stable membranes with an ultra-thin selective layer of advanced polymer materials is highly desirable in membrane technology. Here, we describe a novel polymeric membrane, which is synthesized via the conversion of a surface anchored metal–organic framework (SURMOF) into a surface anchored gel (SURGEL). The SURGEL membranes combine the high variability in the building blocks and the possibility to control the network topology and membrane thickness of the SURMOF synthesis with high mechanical and chemical stability of polymers. Next to the material design, the transfer of membranes to suitable supports is also usually a challenging task, due to the fragile nature of the ultra-thin films. To overcome this issue, we utilized a porous support on top of the membrane, which is mechanically stable enough to allow for the easy membrane transfer from the synthesis substrate to the final membrane support. To demonstrate the potential for gas separation of the synthesized SURGEL membranes, as well as the suitability of the transfer method, we determined the permeance for eight gases with different kinetic diameters

Gas Separation Properties of Polyimide Thin Films on Ceramic Supports for High Temperature Applications

[EN] Novel selective ceramic-supported thin polyimide films produced in a single dip coating step are proposed for membrane applications at elevated temperatures. Layers of the polyimides P84 (R), Matrimid 5218 (R), and 6FDA-6FpDA were successfully deposited onto porous alumina supports. In order to tackle the poor compatibility between ceramic support and polymer, and to get defect-free thin films, the effect of the viscosity of the polymer solution was studied, giving the entanglement concentration (C*) for each polymer. The C* values were 3.09 wt. % for the 6FDA-6FpDA, 3.52 wt. % for Matrimid (R), and 4.30 wt. % for P84 (R). A minimum polymer solution concentration necessary for defect-free film formation was found for each polymer, with the inverse order to the intrinsic viscosities (P84 (R) >= Matrimid (R) >> 6FDA-6FpDA). The effect of the temperature on the permeance of prepared membranes was studied for H-2, CH4, N-2, O-2, and CO2. As expected, activation energy of permeance for hydrogen was higher than for CO2, resulting in H-2/CO2 selectivity increase with temperature. More densely packed polymers lead to materials that are more selective at elevated temperatures.This work was financially supported by the Spanish Government through predoctoral training grants for Centres/units of Excellence "Severo Ochoa" (SEV-2016-0683), which gave S. Escorihuela the opportunity to undertake a research stay at Helmholtz-Zentrum Geesthacht (HZG), Spanish Ministry of Economy and Competitiveness (Project ENE2014-57651-R) and Helmholtz-Zentrum Geesthacht (HZG) through the technology transfer project program and by the Helmholtz Association of German Research Centers through the Helmholtz Portfolio MEMBRAIN. The authors thank M. Schieda and P. Merten for the support in the coating process and viscosity determination, and the microscopy service at Universitat Politecnica de Valencia (UPV) for the FE-SEM images.Escorihuela-Roca, S.; Tena, A.; Shishatskiy, S.; Escolástico Rozalén, S.; Brinkmann, T.; Serra Alfaro, JM.; Abetz, V. (2018). Gas Separation Properties of Polyimide Thin Films on Ceramic Supports for High Temperature Applications. Membranes. 8(1). https://doi.org/10.3390/membranes8010016S8

Self-Assembly of Block Copolymers

Block copolymers and block-copolymer-containing blends represent a fascinating class of soft matter and can self-assemble in a variety of ordered structures on the mesoscale [...

Morphological Control Over Three- and Four-Phase Superstructures in Blends of Asymmetric ABC and BAC Triblock Terpolymers

The versatile and simple attainment of complex superstructures through binary blends of asymmetric polyisoprene‐block‐polystyrene‐block‐poly(methyl methacrylate) (ISM) and polystyrene‐block‐polyisoprene‐block‐poly(methyl methacrylate) (SIM) triblock terpolymers is shown. Different well‐ordered core–shell morphologies with three or four microphases as well as interchanged core‐ and shell‐forming blocks are achieved by different spatial superposition during mixing. Superstructures with three microphases are obtained by antiparallel chain orientation, when ISM and SIM chains align in opposite directions. Similarly, the respective PS, PI, and PMMA blocks are in direct superposition and mix into each other. In contrast, with parallel chain orientation, ISM and SIM chains align in the same direction. It gives rise to four microphases because here, both PI blocks do not assemble into one microdomain, but form two isolated microdomains. These observations are attributed to inverse molecular weight ratios between both blends

Four-Phase Morphologies in Blends of ABC and BAC Triblock Terpolymers

It is investigated how binary blends of two asymmetric triblock terpolymers with the same type of monomers but different block sequences (ABC, BAC) and different block lengths lead to three new ABAC tetrablock terpolymer like morphologies. This study ascribes the formation of four microphases to a parallel chain orientation during the blend process. Because of the resultant spatial superposition, the B‐blocks of both block copolymers can mix into each other as well as both C‐blocks, whereas both A‐blocks form independent microphases. The self‐assembly of nine blends are studied. Their morphologies depend on the blending ratio and are monitored by transmission electron microscopy and small‐angle X‐ray scattering. Besides single morphologies, also coexisting morphologies are obtained, indicating that different superstructures are stable within finite compositional ranges of the blends. This work demonstrates that blending of triblock terpolymers with different block sequence is another interesting way in the huge area of morphological engineering by blending of block copolymers, leading to new and even complex, tailored nanostructures