Multiblock Structure Research Articles

Highly efficient one-pot/one-step synthesis of multiblock copolymers from three-component polymerization of carbon dioxide, epoxide and lactone.

It is a long-standing challenge to combine mixed monomers into multiblock copolymer (MBC) in a one-pot/one-step polymerization manner. We report the first example of MBC with biodegradable polycarbonate and polyester blocks that were synthesized from highly efficient one-pot/one-step polymerization of cyclohexene oxide (CHO), CO2 and ε-caprolactone (ε-CL) in the presence of zinc-cobalt double metal cyanide complex and stannous octoate. In this protocol, two cross-chain exchange reactions (CCER) occurred at dual catalysts respectively and connected two independent chain propagation procedures (i.e., polycarbonate formation and polyester formation) simultaneously in a block-by-block manner, affording MBC without tapering structure. The multiblock structure of MBC was determined by the rate ratio of CCER to the two chain propagations and could be simply tuned by various kinetic factors. This protocol is also of significance due to partial utilization of renewable CO2 and improved mechanical properties of the resultant MBC.

Formation of the chain microstructure in copolyimide synthesis by high-temperature polycondensation in molten benzoic acid

Kinetic features of chain microstructure formation in the synthesis of copolyimides with five-membered imide cycles were studied by the high-temperature polycondensation method in molten benzoic acid from two diamines A and B (comonomers) and one dianhydride C (intermonomer) at 140 ℃ using different regimes of intermonomer loading. The kinetic scheme, including (for the first and second comonomers) the acylation of the amino group with the anhydride fragment, decomposition, and imidization of intermediate amido acid fragments, was examined. The kinetic parameters of the acylation stage necessary for calculation were determined for the model reactions of 9,9-bis(4-aminophenyl)fluorene and 1,12-dodecameth-ylenediamine with phthalic anhydride in acetic acid. The numerical solution of the system of kinetic equations for different regimes of intermonomer loading gave the calculated dependences of the change in time of the average block length and current concentrations of amino and anhydride groups, amido acid fragments (unstable dyads AC1 and BC1), imide cycles (stable dyads AC2 and BC2), and triads. The calculated values of the average block length (l ≈ 4) and microheterogeneity parameter of the chain (K m ≈ 0.5) for the gradual intermonomer loading correspond to the multiblock structure of the chain. These values are in good agreement with the experimental values obtained from the data of 13C NMR spectroscopy for copolyimide based on the indicated diamines and 2,2-propylidenebis(phenyl-4-oxyphthalic acid) dianhydride.

A Design Method of Aero Fuel Centrifugal Pump with Integrated Inducer and Impeller

With the development of the aero engine control technique, aero fuel centrifugal pump with integrated inducer and impeller meet the requirements better than the divided pump. This paper established the hybrid network of the centrifugal pump which adopted multi-block topology structure and octree format, analyzed the internal flow field performance of the pump based on numerical simulation. The simulation datas compared with test datas show that under different calculation conditions, head error of the simulation data and experimental data is less than 1%, and the efficiency value of error is less than 5%. The simulation method can accurately calculate the performance of the pump. The simulation analysis shows that the asymmetry of the impeller internal pressure is appreciable under different flow conditions because of the inlet length, under other small flow conditions. The most dramatic change is the pressure in the impeller channel, and the pressure under large flow conditions is lower than that under other flow conditions. In fixed location of the pressure side, there may produce low speed flow group, the situation is the same as in the entrance to the attachment of back pressure side.

Quantitative modal analysis of optical power flow and energy loss in photonic structures with a dipole emission source.

Fourier modal method based quantitative analysis method of optical power flow and energy loss in general multi-block photonic structures with an internal dipole emitter is described. The analytic expressions of modal power flow and loss are derived for accurate and efficient quantitative analysis. It is revealed that a few dominating excited photonic modes substantially govern the internal energy flow and energy loss. The optical characteristics of the dominant modes are investigated.

Alternating direction method of multipliers for real and complex polynomial optimization models

In this paper, we propose a new method for polynomial optimization with real or complex decision variables. The main ingredient of the approach is to apply the classical alternating direction method of multipliers based on the augmented Lagrangian function. In this particular case, this allows us to fully exploit the multi-block structure of the polynomial functions, even though the optimization model encountered is highly non-linear and non-convex. The new method is shown to be convergent under some conditions, and the numerical results show that the algorithm returns high quality solutions and runs much faster than the two other competing algorithms.

Iterative weighting of multiblock data in the orthogonal partial least squares framework

The integration of multiple data sources has emerged as a pivotal aspect to assess complex systems comprehensively. This new paradigm requires the ability to separate common and redundant from specific and complementary information during the joint analysis of several data blocks. However, inherent problems encountered when analysing single tables are amplified with the generation of multiblock datasets. Finding the relationships between data layers of increasing complexity constitutes therefore a challenging task. In the present work, an algorithm is proposed for the supervised analysis of multiblock data structures. It associates the advantages of interpretability from the orthogonal partial least squares (OPLS) framework and the ability of common component and specific weights analysis (CCSWA) to weight each data table individually in order to grasp its specificities and handle efficiently the different sources of Y-orthogonal variation.Three applications are proposed for illustration purposes. A first example refers to a quantitative structure-activity relationship study aiming to predict the binding affinity of flavonoids toward the P-glycoprotein based on physicochemical properties. A second application concerns the integration of several groups of sensory attributes for overall quality assessment of a series of red wines. A third case study highlights the ability of the method to combine very large heterogeneous data blocks from Omics experiments in systems biology. Results were compared to the reference multiblock partial least squares (MBPLS) method to assess the performance of the proposed algorithm in terms of predictive ability and model interpretability. In all cases, ComDim-OPLS was demonstrated as a relevant data mining strategy for the simultaneous analysis of multiblock structures by accounting for specific variation sources in each dataset and providing a balance between predictive and descriptive purpose.

Modeling Fluid Flow in Faulted Basins

This paper presents a basin simulator designed to better take faults into account, either as conduits or as barriers to fluid flow. It computes hydrocarbon generation, fluid flow and heat transfer on the 4D (space and time) geometry obtained by 3D volume restoration. Contrary to classical basin simulators, this calculator does not require a structured mesh based on vertical pillars nor a multi-block structure associated to the fault network. The mesh follows the sediments during the evolution of the basin. It deforms continuously with respect to time to account for sedimentation, erosion, compaction and kinematic displacements. The simulation domain is structured in layers, in order to handle properly the corresponding heterogeneities and to follow the sedimentation processes (thickening of the layers). In each layer, the mesh is unstructured: it may include several types of cells such as tetrahedra, hexahedra, pyramid, prism, etc. However, a mesh composed mainly of hexahedra is preferred as they are well suited to the layered structure of the basin. Faults are handled as internal boundaries across which the mesh is non-matching. Different models are proposed for fault behavior such as impervious fault, flow across fault or conductive fault. The calculator is based on a cell centered Finite Volume discretisation, which ensures conservation of physical quantities (mass of fluid, heat) at a discrete level and which accounts properly for heterogeneities. The numerical scheme handles the non matching meshes and guaranties appropriate connection of cells across faults. Results on a synthetic basin demonstrate the capabilities of this new simulator.

Fluorenyl phenolphthalein groups containing a multi-block copolymer membrane for alkaline fuel cells

An anion-conducting aromatic multi-block copolymer (PEs-AxBy) was synthesized by a block co-polycondensation reaction between fluorene and phenolphthalein containing oligomers. The quaternized multi-block copolymers (QPEs) resulted in ductile transparent membranes with well-ordered multi-block structures. In chloroform, a thin polymer film (PE-A22B24) with hexagonal well-ordered geometry was obtained. Meanwhile, in NMP/DMAc a dense thin film for QPE-A22B24 was obtained. As an additional attractive feature, the pore structure and pore-geometry of the membrane thin film may be controlled by the membrane casting medium and conditions. The presence of hydrophilic (biphenyl fluorene)–hydrophobic (connector)–hydrophilic (phenolphthalein) groups was responsible for phase separation, and interconnected ion conducting pathways. Among many synthesized anion exchange membranes (AEMs), QPE-A22B24 exhibited excellent stabilities, 0.95–2.24 meq g−1 ion exchange capacity and 95 mS cm−1 conductivity, at 80 °C. The reported AEM retained the conductivity after 1000 h of boiling treatment. QPE-A22B24 membranes were assessed as suitable candidates for alkaline fuel cell applications.

Models for characterizing noise based PCMOS circuits

Quick and accurate error-rate prediction of Probabilistic CMOS (PCMOS) circuits is crucial for their systematic design and performance evaluation. While still in the early stage of research, PCMOS has shown potential to drastically reduce energy consumption at a cost of increased errors. Recently, a methodology has been proposed which could predict the error rates of cascade structures of blocks in PCMOS. This methodology requires error rates of unique blocks to predict the error rates of multiblock cascade structures composed of these unique blocks. In this article we present a new model for characterization of probabilistic circuits/blocks and present a procedure to find and characterize unique circuits/blocks. Unlike prior approaches, our new model distinguishes distinct filtering effects per output, thereby improving prediction accuracy by an average of 95% over the prior art by Palem and coauthors. Furthermore, we show two models where our new model with three stages is 18% more accurate, on average, than our simpler two-stage model. We apply our proposed models to Ripple Carry Adders and Wallace Tree Multipliers and show that using our models, the methodology of cascade structures can predict error rates of PCMOS circuits with reasonable accuracy (within 9%) in PCMOS for uniform voltages as well as multiple voltages. Finally, our approach takes seconds of simulation time whereas using HSPICE would take days of simulation time.

Linear-, Cyclic-, and Multiblock Amphiphilic Polyelectrolytes as Surfactants in Emulsion Polymerization: Role of Topological Structure

Combining atom transfer radical polymerization (ATRP) and “click” chemistry, a set of well-defined amphiphilic block copolymers poly(n-butyl acrylate)-b-poly(acrylic acid) (PnBA20-PAA85) with a similar chemical component, but different topological structures, i.e., linear-, cyclic-, and multiblock structures, were successfully prepared, characterized (size exclusion chromatography (SEC), FT-IR and 1H NMR), and used as surfactants in emulsion polymerization. Our further transmission electron microscopy (TEM) and laser light scattering (LLS) characterization of the resultant latex particles demonstrates all the surfactants with different topologies can effectively stabilize the latex particles but no significant difference among the solids contents was observed. Moreover, we have, for the first time, experimentally established the quantitative relation between the final number of latex particles (Np) and the concentration of polymeric surfactant with different topologies (C), i.e., Np = kCα, and the order of our measured exponent α is as follows: αmulti(1.10) > αlinear(0.81) ≥ αcyclic(0.73), indicating cyclic surfactant molecules behave more like small-molecule surfactants attributed to its strongest unimers extraction and diffusion ability; in contrast, multiblock surfactant molecules can act as seeds to directly nucleate to create latex particles. In addition, Np,multi > Np,linear ≥ Np,cyclic at higher concentration, and Np,linear > Np,cyclic ≥ Np,multi at lower concentration was observed. Similar results (αmulti(1.02) > αlinear(0.65) ≥ αcyclic(0.58)) were also observed when polystyrene-b-poly(acrylic acid) (PS9–PAA60) copolymers were used as surfactants. Further aqueous SEC characterization shows the broad size distribution of our micellar solution has no effect on obtaining narrowly distributed latex particles. Finally, interfacial tension measurement of the micellar solution indicates, compared to multiblock structure, the rate of adsorption at a hydrophobic interface is much faster for linear and cyclic-block structures, agreeing with our observed order of exponent α.

Advanced ultrafiltration membranes based on functionalized poly(arylene ether sulfone) block copolymers

In this study, poly(arylene ether sulfone) (PAES) block copolymer was synthesized from fluoride-terminated oligomer (A16) and hydroxyl terminated oligomer (B12) by aromatic nucleophilic substitution (SNAr) polycondensation reaction. Then allylic free radical substitution reaction at methyl side group using N-bromosuccinimide and benzoyl peroxide was performed to synthesize PAES–CH2Br block copolymer. The chemical structure of PAES and PAES–CH2Br block copolymers was confirmed by 1H-NMR spectroscopy. Gel permeation chromatography was applied to determine the molecular weight and the degree of polymerization of A16 and B12 oligomers, PAES and PAES–CH2Br block copolymers. The synthesized block copolymer had high molecular weight and multiblock structure. Non-solvent induced phase separation of blends of PAES–CH2Br and PAES block copolymers followed by heterogeneous quaternization using trimethyl amine led to hydrophilic positively charged ultrafiltration membranes. Fourier transform infrared spectroscopy in the attenuated total reflection mode, scanning electron microscopy, contact angle, and outer surface zeta potential studies were performed to characterize the resulting membranes. The results confirmed that the prepared membranes were porous, hydrophilic and positively charged. Membranes were also characterized with respect to permeability and then used in ultrafiltration of bovine serum albumin and lysozyme model solutions at varied pH values. Membrane performance depended on the positive charge density which could be adjusted by varying the fraction of PAES–CH2Br in the membrane. Due to the combined effects of size exclusion and charge repulsion, permeability, antifouling properties and protein separation selectivity of membranes could be increased simultaneously with increasing charge density.

Numerical Simulation of Hypersonic Flow Around an Aerospace Plane by Parallel RANS based CFD

This paper deals with a numerical investigation on a complex geometry aerospace plane configuration with no tail fuselage and leaping triangle wing tip similar to HERMES of France. Two case of numerical simulation which including aerodynamic and aerothermodynamics characteristic. Including two case investigation Numerical simulation two cases were performed for performed for Mach number of 4.97(Re=1.3×107) at angles of attack from -5 deg to 20 deg and 8.04(Re=1.13×107) at angles of attack from -5 deg to 18 deg using parallel Multi-block Structure NS solver. Also three different CPU number are used in the investigation. Comparisons method used between the aerodynamic characteristics and wind tunnel data verify the reliability of the numerical method used for simulating viscous flow around the aerospace plane. Numerical results show that the present method is an effective and powerful analysis tool to predict the hypersonic flow field around a complex geometry.

Fluid-dynamics modelling of the human left ventricle with dynamic mesh for normal and myocardial infarction: Preliminary study

Pulsating blood flow patterns in the left ventricular (LV) were computed for three normal subjects and three patients after myocardial infarction (MI). Cardiac magnetic resonance (MR) images were obtained, segmented and transformed into 25 frames of LV for a computational fluid dynamics (CFD) study. Multi-block structure meshes were generated for 25 frames and 75 intermediate grids. The complete LV cycle was modelled by using ANSYS-CFX 12. The flow patterns and pressure drops in the LV chamber of this study provided some useful information on intra-LV flow patterns with heart diseases.

Analysis of the implementability of descriptions with functional indeterminacy based on the verification of conjunctive normal form satisfiability

We consider the problem of the verification of the implementability of a system of partially specified Boolean functions by a multiblock structure in which each block is also determined by a system of partially specified Boolean functions. A method for the solution of the problem by reducing it to the problem of the verification of the satisfiability of a conjunctive normal form that is the union of two the permissible conjunctive normal form of the multiblock structure with the prohibitive conjunctive normal form of the system of partially specified Boolean functions is proposed. Implicative methods for the construction of resolution conjunctive normal forms of multiblock structures with functional indeterminacy are proposed and studied.

Anion Conductive Block Poly(arylene ether)s: Synthesis, Properties, and Application in Alkaline Fuel Cells

Anion conductive aromatic multiblock copolymers, poly(arylene ether)s containing quaternized ammonio-substituted fluorene groups, were synthesized via block copolycondensation of fluorene-containing (later hydrophilic) oligomers and linear hydrophobic oligomers, chloromethylation, quaternization, and ion-exchange reactions. The ammonio groups were selectively introduced onto the fluorene-containing units. The quaternized multiblock copolymers (QPEs) produced ductile, transparent membranes. A well-controlled multiblock structure was responsible for the developed hydrophobic/hydrophilic phase separation and interconnected ion transporting pathway, as confirmed by scanning transmission electron microscopic (STEM) observation. The ionomer membranes showed considerably higher hydroxide ion conductivities, up to 144 mS/cm at 80 °C, than those of existing anion conductive ionomer membranes. The durabilities of the QPE membranes were evaluated under severe, accelerated-aging conditions, and minor degradation was recognized by (1)H NMR spectra. The QPE membrane retained high conductivity in hot water at 80 °C for 5000 h. A noble metal-free direct hydrazine fuel cell was operated with the QPE membrane at 80 °C. The maximum power density, 297 mW/cm(2), was achieved at a current density of 826 mA/cm(2).

Growing multiblock structures: a semi-automated approach to block placement for multiblock hexahedral meshing

Finite element (FE) analysis is a cornerstone of orthopaedic biomechanics research. Three-dimensional medical imaging provides sufficient resolution for the subject-specific FE models to be generated from these data-sets. FE model development requires discretisation of a three-dimensional domain, which can be the most time-consuming component of a FE study. Hexahedral meshing tools based on the multiblock method currently rely on the manual placement of building blocks for mesh generation. We hypothesise that angular analysis of the geometric centreline for a three-dimensional surface could be used to automatically generate building block structures for the multiblock hexahedral mesh generation. Our algorithm uses a set of user-defined points and parameters to automatically generate a multiblock structure based on a surface's geometric centreline. This significantly reduces the time required for model development. We have applied this algorithm to 47 bones of varying geometries and successfully generated a FE mesh in all cases. This work represents significant advancement in automatically generating multiblock structures for a wide range of geometries.

Degradable Depsipeptide-Based Multiblock Copolymers with Polyester or Polyetherester Segments

Polydepsipeptides, alternating copolymers of an a-amino acid and a a-hydroxy acid, are an interesting group of degradable polymers. They have gained attention as potential degradable implant materials. Polydepsipeptides are expected to have better biocompatibility in vivo during the degradation process than aliphatic polyesters. Various depsipeptide-based polymers with or without pendant functional groups have been synthesized via ring-opening polymerization of corresponding morpholine-2,5-dione derivatives. The different polymer architectures of the polymers, for example, providing an alternating, random, diblock, triblock, or multiblock structure, can be obtained by appropriate selection of the polymerization reaction, which may be ring-opening or polyaddition. Recently, we synthesized thermoplastic phase-segregated copolymers with a multiblock structure containing polydepsipeptides and poly(e-caprolactone) or poly(p-dioxanone) segments via coupling of the respective diols using an aliphatic diisocyanate. The obtained multiblock copolymers showed good elastic properties at 25 °C and 75 °C. Furthermore, they exhibited a shape-memory capability. Here, we summarize the synthesis, biodegradation behavior and shape-memory properties of the multiblock copolymers. In addition, we introduce new combinations of depsipeptide/poly(ether)ester segments in multiblock copolymers. The depsipeptide-based multiblock copolymers have potential applications as biomaterials for controlled drug release, tissue engineering scaffolds, or base materials for biofunctional implants.

Broadband Propagative Microwave Imaging of Steel Fiber Reinforced Concrete Wall Structures

In this paper, a system for the broadband microwave nondestructive testing of steel fiber reinforced concrete (SFRC) is presented. The system is able to produce a pixeled image of the fiber dosage in the concrete. The SFRC material is seen as a dielectric mixture formed by thin-wire metallic inclusions and a host medium. An electromagnetic model based on the Maxwell-Garnett approach for dielectric mixtures is used to relate the electromagnetic properties of the SFRC to the fiber dosage. A criterion to determine the practical upper frequency limit for the measurements is formulated. A measurement system based on two wideband waveguide antennas is designed for the analysis of two SFRC multiblock test structures. The electric capacitive host medium calibration is proposed in the cases where the concrete structures have parts fabricated with different processes. The laboratory measurements on the individual SFRC elements and on the SFRC multiblock structures are conducted to obtain the images of the fiber dosage in the SFRC. Good agreement between the real, simulated, and measured values is achieved.

Progress in Depsipeptide‐Based Biomaterials

Polydepsipeptides - alternating copolymers of an alpha-amino acid and an alpha-hydroxy acid - are a group of biodegradable polymers. Versatile polydepsipeptides with or without pendant functional groups, as well as various polymer architectures, for example, providing alternative, random, diblock, triblock, multiblock or graft sequence structures, can be synthesized via ring-opening copolymerization of various morpholine-2,5-dione derivatives. They are potential candidates for a wide range of biomedical applications. Polydepsipeptides are described in this review from the aspect of materials science, especially as biomaterials. We mainly focus on various techniques developed to synthesize polydepsipeptides and their copolymers, biodegradation behaviors, shape-memory properties and possible biomedical applications.

Synthesis and characterization of nanostructured-segmented block copolyetheramide based on nylon6 and poly(ethylene oxide)

Segmented block copolymer based on nylon6 (N6) and polyethylene oxide (PEO) with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic acid leading to carboxy terminated N6, and the second one is polycondensation of the latter product with PEO in the presence of catalyst and thermostabilizer to form a high molecular weight multi-block copolymer. Several methods were applied to characterize the synthesized copolymer such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. The obtained results confirmed the multi-block structure for copolymer with a very high degree of micro-phase separation. Atomic force microscopy micrographs indicated that the morphology was the dispersion of high stiffness nanostructured polyamide (PA) domains in the amorphous region of PEO matrix, which can be very important in their performance for membrane processes.