Recent Submissions

  • Design Criteria for Horseshoe and Spiral-Based Interconnects for Highly Stretchable Electronic Devices

    Qaiser, Nadeem; Damdam, Asrar Nabil; Khan, Sherjeel Munsif; Bunaiyan, Saleh; Hussain, Muhammad Mustafa (Advanced Functional Materials, Wiley, 2020-10-28) [Article]
    Stretchable electronics can be used for numerous advanced applications such as soft and wearable actuators, sensors, bio-implantable devices, and surgical tools because of their ability to conform to curvilinear surfaces, including human skin. The efficacy of these devices depends on the development of stretchable geometries such as interconnection-based configurations and the associated mechanics that helps to achieve optimum configurations. This work presents the essential mechanics of silicon (Si) island-interconnection structures, which include horseshoe and spiral interconnections, without reducing the areal efficiency. In particular, this study demonstrates the range of the geometrical parameters where they have a high stretchability and cyclic life. The numerical results predict the areas that are prone to breaking followed by experimental validation. The figure-of-merit for these configurations is achieved by mapping the fracture-free zones for in-plane and out-of-plane stretching with essential implications in stretchable and wearable system design. Furthermore, this work demonstrates the mechanical response for a range of materials (i.e., copper, gold, aluminum, silver, and graphene) that experience the plastic deformations in contrast to conventionally used Si-based devices that represent the extended usage for advanced stretchable electronic devices. The detailed mechanics of these configurations provides comprehensive guidelines to manufacture wearable and stretchable electronic devices.
  • Ultra-compact terahertz plasmonic wavelengthdiplexer

    Yuan, Mingrui; Wang, Qingwei; Li, Yanfeng; Zhang, Xixiang; Han, Jiaguang; Zhang, Weili (Applied Optics, The Optical Society, 2020-10-28) [Article]
    Terahertz (THz) spoof surface plasmon polariton (SPP) waveguides can provide subwavelength confinement, which makes it possible for the THz waves to transmit at low loss over long distances along a metallic surface. In this work, an ultra-compact wavelength diplexer formed by THz spoof SPP waveguiding structures is reported on the design and actualization. By adding a certain number of periodic pillars in the coupling part of the directional coupler, the refractive index of the anti-symmetrically distributed odd modes can be engineered, thereby adjusting the coupling length. By adjusting the periodic pillar parameters properly, the SPP modes at two target frequencies will be coupled in the device for an odd or even number of times, so that SPP modes at these two frequencies can be coupled out from different ports. The length of the wavelength diplexer is 1.6 mm, which is about 12.8% of its traditional counterpart. Minimum simulated transmittances of -24.34 dB and -26.27 dB can be obtained at 0.637 THz and 0.667 THz, respectively. The insertion losses at the two operating frequencies are less than 0.46 dB, and the extinction ratios are both better than 19 dB. By cascading the proposed diplexers, a compact wavelength demultiplexer with more channels can be obtained, which has important applications for future THz integrated communication systems.
  • Spatial hierarchical modeling of threshold exceedances using rate mixtures

    Yadav, Rishikesh; Huser, Raphaël; Opitz, Thomas (Environmetrics, Wiley, 2020-10-27) [Article]
    We develop new exible univariate models for light-tailed and heavy-tailed data, which extend a hierarchical representation of the generalized Pareto (GP) limit for threshold exceedances. These models can accommodate departure from asymptotic threshold stability in finite samples while keeping the asymptotic GP distribution as a special (or boundary) case and can capture the tails and the bulk jointly without losing much exibility. Spatial dependence is modeled through a latent process, while the data are assumed to be conditionally independent. Focusing on a gamma-gamma model construction, we design penalized complexity priors for crucial model parameters, shrinking our proposed spatial Bayesian hierarchical model toward a simpler reference whose marginal distributions are GP with moderately heavy tails. Our model can be fitted in fairly high dimensions using Markov chain Monte Carlo by exploiting the Metropolis-adjusted Langevin algorithm (MALA), which guarantees fast convergence of Markov chains with efficient block proposals for the latent variables. We also develop an adaptive scheme to calibrate the MALA tuning parameters. Moreover, our model avoids the expensive numerical evaluations of multifold integrals in censored likelihood expressions. We demonstrate our new methodology by simulation and application to a dataset of extreme rainfall events that occurred in Germany. Our fitted gamma-gamma model provides a satisfactory performance and can be successfully used to predict rainfall extremes at unobserved locations.
  • Role of Buffer Layer and Building Unit in the Monolayer CrI3 Growth: A First-Principles Perspective

    Han, Nannan; Yang, Dian; Zhang, Chenhui; Zhang, Xixiang; Shao, Jinjun; Cheng, Yingchun; Huang, Wei (The Journal of Physical Chemistry Letters, American Chemical Society (ACS), 2020-10-27) [Article]
    CrI3, a two-dimensional layered material, has recently attracted a lot of research interest due to its exotic magnetic property. However, the synthesis of a CrI3 monolayer (ML) by vapor-phase deposition has not been achieved by current experimental endeavors, which require a better understanding of the vapor-phase growth mechanism involved. In this study, we theoretically simulate the growth of the CrI3 ML on the Si(111) surface by using a first-principles calculation. Our key finding is that an iodine buffer layer on the Si surface is crucial to the formation of the CrI3 ML by stabilizing the precursor and also reacting with the precursor. Moreover, our simulation reveals that the CrI2 cluster as the growth building unit, which can be formed by controlling the chemical potential of the I source, is preferred for the formation of CrI3 ML. We think that our work will provide insightful guidance for the experimental synthesis of CrI3 ML in the future.
  • High-color-rendering-index phosphor-free InGaN-based white light-emitting diodes by carrier injection enhancement via V-pits

    Iida, Daisuke; Zhuang, Zhe; Kirilenko, Pavel; Velazquez-Rizo, Martin; Ohkawa, Kazuhiro (Applied Physics Letters, AIP Publishing, 2020-10-27) [Article]
    We herein report the growth of phosphor-free InGaN-based white light-emitting diodes (LEDs) by metalorganic vapor-phase epitaxy. The active region consists of blue and red InGaN quantum wells (QWs). To improve the current injection and generate broadband emission, the V-pit structures in the LEDs were fabricated intentionally before growing the QWs. The monolithic white LEDs emit in the range of 410–770 nm and, by tuning the injection current, can cover correlated color temperature (CCT) values corresponding to warm white, natural white, and cool white. The color-rendering index (CRI) of the white LEDs reaches 88 at an injection current of 10 mA. At an injection current of 30 mA, the white LEDs exhibit the chromaticity coordinates of (0.320 and 0.334) in the Commission Internationale de l’Eclairage 1931 chromaticity diagram, a CRI of 78, and a CCT of 6110 K.
  • Surface-Enhanced Raman Spectroscopy of Organic Molecules and Living Cells with Gold-Plated Black Silicon.

    Golubewa, Lena; Karpicz, Renata; Matulaitiene, Ieva; Selskis, Algirdas; Rutkauskas, Danielis; Pushkarchuk, Aliaksandr; Khlopina, Tatsiana; Michels, Dominik L.; Lyakhov, Dmitry; Kulahava, Tatsiana; Shah, Ali; Svirko, Yuri; Kuzhir, Polina (ACS applied materials & interfaces, American Chemical Society (ACS), 2020-10-27) [Article]
    Black silicon (bSi) refers to an etched silicon surface comprising arrays of microcones that effectively suppress reflection from UV to near-infrared (NIR) while simultaneously enhancing the scattering and absorption of light. This makes bSi covered with a nm-thin layer of plasmonic metal, i.e., gold, an attractive substrate material for sensing of bio-macromolecules and living cells using surface-enhanced Raman spectroscopy (SERS). The performed Raman measurements accompanied with finite element numerical simulation and density functional theory analysis revealed that at the 785 nm excitation wavelength, the SERS enhancement factor of the bSi/Au substrate is as high as 108 due to a combination of electromagnetic and chemical mechanisms. This finding makes the SERS-active bSi/Au substrate suitable for detecting trace amounts of organic molecules. We demonstrate the outstanding performance of this substrate by highly sensitive and specific detection of a small organic molecule of 4-mercaptobenzoic acid and living C6 rat glioma cell nucleic acids/proteins/lipids. Specifically, the bSi/Au SERS-active substrate offers a unique opportunity to investigate the living cells' malignant transformation using characteristic protein disulfide Raman bands as a marker. Our findings evidence that bSi/Au provides a pathway to the highly sensitive and selective, scalable, and low-cost substrate for lab-on-a-chip SERS biosensors that can be integrated into silicon-based photonics devices.
  • Recent developments in the control of selectivity in hydrogenation reactions by confined metal functionalities

    Zaarour, Moussa; Cazemier, Jurjen; Ruiz-Martinez, Javier (Catalysis Science & Technology, Royal Society of Chemistry (RSC), 2020-10-27) [Article]
    Confining metal active species in the voids of porous solid matrices such as zeolites, metal–organic frameworks (MOFs), and carbon nanotubes (CNTs) can bring fascinating key advantages in the field of selective hydrogenation reactions.
  • Addition of a carbon fiber brush improves anaerobic digestion compared to external voltage application

    Baek, Gahyun; Saikaly, Pascal; Logan, Bruce (Water Research, Elsevier BV, 2020-10-26) [Article]
    Two methods were examined to improve methane production efficiency in anaerobic digestion (AD) based on adding a large amount of surface area using a single electrically conductive carbon brush, or by adding electrodes as done in microbial electrolysis cells (MECs) to form a hybrid AD-MEC. To examine the impact of surface area relative to electrodes, AD reactors were fitted with a single large brush without electrodes (FB), half a large brush with two electrodes with an applied voltage (0.8 V) and operated in closed circuit (HB-CC) or open circuit (HB-OC) mode, or only two electrodes with a closed circuit and no large brush (NB-CC) (equivalent to an MEC). The three configurations with a half or full brush all had improved performance as shown by 57-82% higher methane generation rate parameters in the Gompertz model compared to NB-CC. The retained biomass was much higher in the reactors with large brush, which likely contributed to the rapid consumption of volatile fatty acids (VFAs) and therefore improved AD performance. A different microbial community structure was formed in the large-size brushes compared to the electrodes. Methanothrix was predominant in the biofilm of large-size carbon brush, while Geobacter (anode) and Methanobacterium (cathode) were highly abundant in the electrode biofilms. These results demonstrate that adding a high surface area carbon fiber brush will be a more effective method of improving AD performance than using MEC electrodes with an applied potential.
  • Mechanically flexible viscosity sensor for real-time monitoring of tubular architectures for industrial applications

    Nour, Maha A.; Khan, Sherjeel M.; Qaiser, Nadeem; Bunaiyan, Saleh A.; Hussain, Muhammad Mustafa (Engineering Reports, Wiley, 2020-10-26) [Article]
    Real-time monitoring of fluid viscosities in tubular systems is essential for industries transporting fluid media. The available real-time viscometers for tubular systems have major drawbacks, such as using invasive methods with large pressure drops due to flow disturbances, destructive installation processes with permanent tube damage, and limited operability with laminar flows. Therefore, developing a viscometer to address the above-mentioned concerns is required for industrial applications. In this study, a new application of a velocity-dependent viscometer using a novel design for real-time measurements with insignificant flow disruption is proposed. It involves a Poly (methyl-methacrylate) microchannel bridge with a microfluidic flowmeter attached to a mechanically flexible Polydimethylsiloxane platform connected to the inner surface of the pipe, which can adapt to different pipe diameters and curvatures. Moreover, the proposed viscometer uses the pipe flow driving force to flow fluids into the microchannel for measurement without requiring a pumping system or any sample withdrawals. The results of the simulation analysis match the experimental results of the sensor performance. The sensor can measure different viscosities in the range of 4-334 mPa s with a resolution higher than 2.7 mPa s. Finally, a stand-alone system is integrated with the sensor for wireless data transmission.
  • Intrinsic efficiency limits in low-bandgap non-fullerene acceptor organic solar cells

    Karuthedath, Safakath; Gorenflot, Julien; Firdaus, Yuliar; Chaturvedi, Neha; De Castro, Catherine S. P.; Harrison, George T.; Khan, Jafar Iqbal; Markina, Anastasia; Albalawi, Ahmed; Peña, Top Archie Dela; Liu, Wenlan; Liang, Ru-Ze; Sharma, Anirudh; Paleti, Sri Harish Kumar; Zhang, Weimin; Lin, Yuanbao; Alarousu, Erkki; Anjum, Dalaver H.; Beaujuge, Pierre; De Wolf, Stefaan; McCulloch, Iain; Anthopoulos, Thomas D.; Baran, Derya; Andrienko, Denis; Laquai, Frédéric (Nature Materials, Springer Science and Business Media LLC, 2020-10-26) [Article]
    In bulk heterojunction (BHJ) organic solar cells (OSCs) both the electron affinity (EA) and ionization energy (IE) offsets at the donor–acceptor interface should equally control exciton dissociation. Here, we demonstrate that in low-bandgap non-fullerene acceptor (NFA) BHJs ultrafast donor-to-acceptor energy transfer precedes hole transfer from the acceptor to the donor and thus renders the EA offset virtually unimportant. Moreover, sizeable bulk IE offsets of about 0.5 eV are needed for efficient charge transfer and high internal quantum efficiencies, since energy level bending at the donor–NFA interface caused by the acceptors’ quadrupole moments prevents efficient exciton-to-charge-transfer state conversion at low IE offsets. The same bending, however, is the origin of the barrier-less charge transfer state to free charge conversion. Our results provide a comprehensive picture of the photophysics of NFA-based blends, and show that sizeable bulk IE offsets are essential to design efficient BHJ OSCs based on low-bandgap NFAs.
  • Clustered spatio-temporal varying coefficient regression model.

    Lee, Junho; Kamenetsky, Maria E; Gangnon, Ronald E; Zhu, Jun (Statistics in medicine, Wiley, 2020-10-26) [Article]
    In regression analysis for spatio-temporal data, identifying clusters of spatial units over time in a regression coefficient could provide insight into the unique relationship between a response and covariates in certain subdomains of space and time windows relative to the background in other parts of the spatial domain and the time period of interest. In this article, we propose a varying coefficient regression method for spatial data repeatedly sampled over time, with heterogeneity in regression coefficients across both space and over time. In particular, we extend a varying coefficient regression model for spatial-only data to spatio-temporal data with flexible temporal patterns. We consider the detection of a potential cylindrical cluster of regression coefficients based on testing whether the regression coefficient is the same or not over the entire spatial domain for each time point. For multiple clusters, we develop a sequential identification approach. We assess the power and identification of known clusters via a simulation study. Our proposed methodology is illustrated by the analysis of a cancer mortality dataset in the Southeast of the U.S.
  • Derivation of two naturally isogenic iPSC lines (KAUSTi006-A and KAUSTi006-B) from a mosaic Klinefelter Syndrome patient (47-XXY/46-XY).

    Fiacco, Elisabetta; Alowaysi, Maryam; Astro, Veronica; Adamo, Antonio (Stem cell research, Elsevier BV, 2020-10-23) [Article]
    While Klinefelter Syndrome (KS) has a prevalence of 85-250 per 100,000 born males, patients are typically underdiagnosed due to a subtle phenotype emerging only late during puberty or adulthood. Rare cases of KS carry a mosaic phenotype 47-XXY/46-XY associated to mild phenotypic traits mostly compatible with a normal life including preserved fertility. From a genetic modeling perspective, the derivation of naturally isogenic iPSCs from mosaic patients allows the comparison of disease and healthy cells carrying a virtually identical genomic background.
  • Hierarchical Matrix Approximations of Hessians Arising in Inverse Problems Governed by PDEs

    Ambartsumyan, Ilona; Boukaram, Wagih Halim; Bui-Thanh, Tan; Ghattas, Omar; Keyes, David E.; Stadler, Georg; Turkiyyah, George; Zampini, Stefano (SIAM Journal on Scientific Computing, Society for Industrial & Applied Mathematics (SIAM), 2020-10-23) [Article]
    Hessian operators arising in inverse problems governed by partial differential equations (PDEs) play a critical role in delivering efficient, dimension-independent convergence for Newton solution of deterministic inverse problems, as well as Markov chain Monte Carlo sampling of posteriors in the Bayesian setting. These methods require the ability to repeatedly perform operations on the Hessian such as multiplication with arbitrary vectors, solving linear systems, inversion, and (inverse) square root. Unfortunately, the Hessian is a (formally) dense, implicitly defined operator that is intractable to form explicitly for practical inverse problems, requiring as many PDE solves as inversion parameters. Low rank approximations are effective when the data contain limited information about the parameters but become prohibitive as the data become more informative. However, the Hessians for many inverse problems arising in practical applications can be well approximated by matrices that have hierarchically low rank structure. Hierarchical matrix representations promise to overcome the high complexity of dense representations and provide effective data structures and matrix operations that have only log-linear complexity. In this work, we describe algorithms for constructing and updating hierarchical matrix approximations of Hessians, and illustrate them on a number of representative inverse problems involving time-dependent diffusion, advection-dominated transport, frequency domain acoustic wave propagation, and low frequency Maxwell equations, demonstrating up to an order of magnitude speedup compared to globally low rank approximations.
  • Recovery of renewable aromatic and aliphatic hydrocarbon resources from microwave pyrolysis/co-pyrolysis of agro-residues and plastics wastes.

    Suriapparao, Dadi V; Yerrayya, Attada; Nagababu, Garlapati; Guduru, Ramesh K; Kumar, Tanneru Hemanth (Bioresource technology, Elsevier BV, 2020-10-22) [Article]
    The present study focussed on recovering the valuable carbon resources from agro-residues (wheat straw, rice husk) and waste plastics (polypropylene, polystyrene) using microwave pyrolysis and co-pyrolysis. The main objective of this study is to investigate the effect of the susceptor blending mechanism on the co-pyrolysis product distribution. Graphite was mixed with feedstock in a new approach to achieving homogeneity, and microwave power of 600 W was used. The average heating rate (52-67 (°C/min)), microwave energy required (2267-2936 (J/g)), heat energy utilized (1410-1444 (J/g)), and conductive heat losses (85-110 (J/g)) were analyzed. The selectivity of cyclic alkanes and alkenes (65.5%) was found to be high in polypropylene pyrolysis oil. Polystyrene pyrolysis oil predominantly contained cyclooctatetraene (61%) compound. Bio-oil obtained from wheat straw predominantly contained aromatic hydrocarbons (85%), whereas rice husk oil also contains high selectivity aromatic hydrocarbons (37.8%) along with aliphatic hydrocarbons (54.9%). The co-pyrolysis oils has high selectivity of aromatics.
  • Enzymatic Formation of an Artificial Base Pair Using a Modified Purine Nucleoside Triphosphate

    Flamme, Marie; Röthlisberger, Pascal; Levi-Acobas, Fabienne; Chawla, Mohit; Oliva, Romina; Cavallo, Luigi; Gasser, Gilles; Marlière, Philippe; Herdewijn, Piet; Hollenstein, Marcel (ACS Chemical Biology, American Chemical Society (ACS), 2020-10-22) [Article]
    The expansion of the genetic alphabet with additional, unnatural base pairs (UBPs) is an important and long-standing goal in synthetic biology. Nucleotides acting as ligands for the coordination of metal cations have advanced as promising candidates for such an expansion of the genetic alphabet. However, the inclusion of artificial metal base pairs in nucleic acids mainly relies on solid-phase synthesis approaches, and very little is known about polymerase-mediated synthesis. Herein, we report the selective and high yielding enzymatic construction of a silver-mediated base pair (dImC-AgI-dPurP) as well as a two-step protocol for the synthesis of DNA duplexes containing such an artificial metal base pair. Guided by DFT calculations, we also shed light into the mechanism of formation of this artificial base pair as well as into the structural and energetic preferences. The enzymatic synthesis of the dImC-AgI-dPurP artificial metal base pair provides valuable insights for the design of future, more potent systems aiming at expanding the genetic alphabet.
  • Covalent Organic Framework Embedded with Magnetic Nanoparticles for MRI and Chemo-Thermotherapy

    Benyettou, Farah; Das, Gobinda; Nair, Anjana Ramdas; Prakasam, Thirumurugan; Shinde, Digambar; Sharma, Sudhir Kumar; Whelan, Jamie; Lalatonne, Yoann; Traboulsi, Hassan; Pasricha, Renu; Abdullah, Osama; Jagannathan, Ramesh; Lai, Zhiping; Motte, Laurence; Gándara, Felipe; Sadler, Kirsten C.; Trabolsi, Ali (Journal of the American Chemical Society, American Chemical Society (ACS), 2020-10-22) [Article]
    Nanoscale imine-linked covalent organic frameworks (nCOFs) were first loaded with the anticancer drug Doxorubicin (Dox), coated with magnetic iron oxide nanoparticles (γ-Fe2O3 NPs), and stabilized with a shell of poly(l-lysine) cationic polymer (PLL) for simultaneous synergistic thermo-chemotherapy treatment and MRI imaging. The pH responsivity of the resulting nanoagents (γ-SD/PLL) allowed the release of the drug selectively within the acidic microenvironment of late endosomes and lysosomes of cancer cells (pH 5.4) and not in physiological conditions (pH 7.4). γ-SD/PLL could efficiently generate high heat (48 °C) upon exposure to an alternating magnetic field due to the nCOF porous structure that facilitates the heat conduction, making γ-SD/PLL excellent heat mediators in an aqueous solution. The drug-loaded magnetic nCOF composites were cytotoxic due to the synergistic toxicity of Dox and the effects of hyperthermia in vitro on glioblastoma U251-MG cells and in vivo on zebrafish embryos, but they were not significantly toxic to noncancerous cells (HEK293). To the best of our knowledge, this is the first report of multimodal MRI probe and chemo-thermotherapeutic magnetic nCOF composites.
  • Hydrated Mg x V 5 O 12 Cathode with Improved Mg 2+ Storage Performance

    Zhu, Yunpei; Huang, Gang; Yin, Jun; Lei, Yongjiu; Emwas, Abdul-Hamid; Yu, Xiang; Mohammed, Omar F.; Alshareef, Husam N. (Advanced Energy Materials, Wiley, 2020-10-22) [Article]
    Mg-ion batteries (MIBs) possess promising advantages over monovalent Li-ion battery technology. However, one of the myriad obstacles in realizing highly efficient MIBs is a limited selection of cathode materials that can enable reversible, stable Mg2+ intercalation at a high operating voltage. Here, a scalable method is showcased to synthesize a hydrated MgxV5O12 cathode, which shows a high capacity of ≈160 mAh g−1 with a high voltage of 2.1 V, a decent rate capability, and an outstanding cycling life (e.g., 81% capacity retention after 10 000 cycles). The combination of in situ and ex situ characterizations and first-principles calculations provides evidence of reversible, facile topochemical Mg2+ intercalation into the expanded 2D channels of the hydrated MgxV5O12 cathode, which results from the synergistic effects of Mg2+ pillars and structural H2O. The findings underscore the advantage of the rich but controllable chemistry of vanadium oxide bronzes in achieving practical multivalent cation mobility.
  • On the robustness and performance of entropy stable collocated discontinuous Galerkin methods

    Rojas, Diego B.; Boukharfane, Radouan; Dalcin, Lisandro; Del Rey Fernández, David C.; Ranocha, Hendrik; Keyes, David E.; Parsani, Matteo (Journal of Computational Physics, Elsevier BV, 2020-10-22) [Article]
    In computational fluid dynamics, the demand for increasingly multidisciplinary reliable simulations, for both analysis and design optimization purposes, requires transformational advances in individual components of future solvers. At the algorithmic level, hardware compatibility and efficiency are of paramount importance in determining viability at exascale and beyond. However, equally important (if not more so) is algorithmic robustness with minimal user intervention, which becomes progressively more challenging to achieve as problem size and physics complexity increase. We numerically show that low and high order entropy stable collocated discontinuous Galerkin discretizations based on summation-by-part operators and simultaneous-approximationterms technique provide an essential step toward a truly enabling technology in terms of reliability and robustness for both under-resolved turbulent flow simulations and flows with discontinuities.
  • Spreading of Normal Liquid Helium Drops

    Mallin, David; Langley, Kenneth; Aguirre-Pablo, Andres A.; Wallace, Matthew L.; Milgie, Michael; Thoroddsen, Sigurdur T; Taborek, P. (Physical Review E, American Physical Society (APS), 2020-10-21) [Article]
    We have used video imaging and interferometric techniques to investigate the dynamics of spreading of drops of 4He on a solid surface for temperatures ranging from 5.2 K (near the critical point) to 2.2 K (near Tλ). After an initial transient, the drops become pancake-shaped with a radius that grows as R(t) ≈ t α, with α =0.149 ± 0.002. The drops eventually begin to shrink due to evaporation driven by gravitational and curvature effects, which limits their lifetime to about 1000 s. Although helium completely wets the substrate, and the spreading takes place over a pre-existing adsorbed film, a distinct contact line with a contact angle of order one degree is visible throughout this process.
  • Electropolymerization of robust conjugated microporous polymer membranes for rapid solvent transport and narrow molecular sieving

    Zhou, Zongyao; Li, Xiang; Guo, Dong; Shinde, Digambar; Lu, Dongwei; Chen, Long; Liu, Xiaowei; Cao, Li; Aboalsaud, Ammar M.; Hu, Yunxia; Lai, Zhiping (Nature Communications, Springer Science and Business Media LLC, 2020-10-21) [Article]
    Abstract Pore size uniformity is one of the most critical parameters in determining membrane separation performance. Recently, a novel type of conjugated microporous polymers (CMPs) has shown uniform pore size and high porosity. However, their brittle nature has prevented them from preparing robust membranes. Inspired by the skin-core architecture of spider silk that offers both high strength and high ductility, herein we report an electropolymerization process to prepare a CMP membrane from a rigid carbazole monomer, 2,2’,7,7’-tetra(carbazol-9-yl)-9,9’-spirobifluorene, inside a robust carbon nanotube scaffold. The obtained membranes showed superior mechanical strength and ductility, high surface area, and uniform pore size of approximately 1 nm. The superfast solvent transport and excellent molecular sieving well surpass the performance of most reported polymer membranes. Our method makes it possible to use rigid CMPs membranes in pressure-driven membrane processes, providing potential applications for this important category of polymer materials.

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