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Facile Fabrication of Conductive Paper-based Materials from Tunicate Cellulose Nanocrystals and Polydopamine-decorated Graphene Oxide

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Paper And Biomaterials 2018年第4期3卷 19-25页

作者： XiaoZhou Ma YaoYao Chen Peter R. Chang Jin Huang School of Chemistry and Chemical Engineering Joint International Research Laboratory of Bio-mass-Based Macromolecular Chemistry and Materials Southwest University Chongqing 400715 China School of Chemistry Chemical Engineering and Life Sciences Wuhan University of Technology Wuhan Hubei Province 430070 China Bioproducts and Bioprocesses National Science Program Agriculture and Agri-Food Canada 107 Science Place Saskatoon SK S7N 0X2 Canada

Conductive papers made from graphene and its derivatives are important for the development of electronic devices; however, elastomer-based matrices usually make it difficult for the conductive sheets to form continuous conductive networks. In this work, we used tunicate-derived cellulose nanocrystals （TCNC） instead of traditional elastomers as the matrix for polydopamine （PDA）-coated and reduced graphene oxide （GO） to prepare conductive paper, which, at a low concentration, were better for the formation of conductive networks from conductive sheets. It was found that the Young’s modulus of the conductive paper produced via this strategy reached as high as 7 GPa. Meanwhile, owing to the partial reduction of GO during the polymerization of dopamine, the conductivity of the conductive paper reached as high as 1.3×10-5 S/cm when the PDA-coated GO content was 1 wt%, which was much higher than the conductivity of pure GO （-4.60×10-8 S/cm）. This work provides a new strategy for preparing environmentally friendly conductive papers with good mechanical properties and low conductive fller content, which may be used to produce high-performance, low-cost electronic devices.

关键词： conductive paper tunicate cellulose nanocrystal graphene oxide polydopamine coating casting paper

Review of Cellulose Nanocrystal-based Fluorophore Materials and Their Application in Metal Ion Detection

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Paper And Biomaterials 2018年第4期3卷 45-61页

作者： Ya Wang Alain Dufresne Peter R. Chang XiaoZhou Ma Jin Huang School of Chemistry and Chemical Engineering Joint International Research Laboratory of Biomass-Based Macromolecular Chemistry and Materials Southwest University Chongqing 400715 China Université Grenoble Alpes CNRS Grenoble INP LGP2 F-38000 Grenoble France Bioproducts and Bioprocesses National Science Program Agriculture and Agri-Food Canada 107 Science Place Saskatoon SK S7N0X2 Canada

Cellulose nanocrystals （CNCs）, a unique and promising natural material extracted from native cellulose, have attracted considerable attention owing to their physical properties and special surface chemistry. This review focuses on chemical conjugation strategies that can be used for preparation of ？uorescent-molecule labeled CNCs and the development of biomaterials. Furthermore, their application in the detection of metal ions and future development prospects are discussed. We hope to provide a clear view of the strategies for surface fluorescent modifcation of CNCs and their application in detection of metal ions.

关键词： fluorescent cellulose nanocrystals detection of metal ions sensors optical imaging biomaterial

Pressure-Tunable Photonic Band Gaps in an Entropic Colloidal Crystal

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arXiv 2018年

作者： Cersonsky, Rose K. Dshemuchadse, Julia Antonaglia, James Anders, Greg Van Glotzer, Sharon C. Macromolecular Science and Engineering Program University of Michigan Ann ArborMI48109 United States Department of Chemical Engineering University of Michigan Ann ArborMI48109 United States Department of Physics University of Michigan Ann ArborMI48104 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Biointerfaces Institute University of Michigan Ann ArborMI48109 United States

Materials adopting the diamond structure possess useful properties in atomic and colloidal systems, and are a popular target for synthesis in colloids where a photonic band gap is possible. The desirable photonic properties of the diamond structure pose an interesting opportunity for reconfigurable matter: Can we create a colloidal crystal able to switch reversibly to and from the diamond structure? Drawing inspiration from highpressure transitions of diamond-forming atomic systems, we design a system of polyhedrally-shaped particles that transitions from diamond to a tetragonal diamond derivative upon a small pressure change. The transition can alternatively be triggered by changing the shape of the particle in-situ. We propose that the transition provides a reversible reconfiguration process for a potential new colloidal material, and draw parallels between this transition and phase behavior of the atomic transitions from which we take inspiration. Copyright © 2018, The Authors. All rights reserved.

关键词： Diamonds

Room‐Temperature Ferroelectricity in an Organic Cocrystal

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Angewandte Chemie 2018年第29期130卷

作者： Ren A. Wiscons N. Rajesh Goud Joshua T. Damron Adam J. Matzger Department of Chemistry and the Macromolecular Science and Engineering Program University of Michigan 930 North University Avenue Ann Arbor MI 48109-1055 USA

Ferroelectric materials exhibit switchable remanent polarization due to reversible symmetry breaking under an applied electric field. Previous research has leveraged temperature‐induced neutral‐ionic transitions in charge‐transfer (CT) cocrystals to access ferroelectrics that operate through displacement of molecules under an applied field. However, displacive ferroelectric behavior is rare in organic CT cocrystals and achieving a Curie temperature ( T C ) above ambient has been elusive. Here a cocrystal between acenaphthene and 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane is presented that shows switchable remanent polarization at room temperature ( T C =68 °C). Raman spectroscopy, X‐ray diffraction, and solid‐state NMR spectroscopy indicate the ferroelectric behavior is facilitated by acenaphthene (AN) rotation, deviating from conventional design strategies for CT ferroelectrics. These findings highlight the relevance of non‐CT interactions in the design of displacive ferroelectric cocrystals.

关键词： Ferroelektrika Kristall-engineering Ladungstransfer Organische Elektronik Polarisierung

The role of molecular properties on the dimerization of aromatic compounds

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arXiv 2017年

作者： Elvati, Paolo Turrentine, Kirk Violi, Angela Department of Mechanical Engineering University of Michigan Ann ArborMI48109-2125 United States Departments of Chemical Engineering Biomedical Engineering Macromolecular Science and Engineering Biophysics Program University of Michigan Ann ArborMI United States

Recent results have shown the presence and importance of oxygen chemistry during the growth of aromatic compounds, leading to the formation of oxygenated structures that have been identified in various environments. Since the formation of polycyclic aromatic compounds (PAC) bridge the formation of gas-phase species with particle inception, in this work we report a detailed analysis of the effects of molecular characteristics on physical growth of PAC via dimerization. We have included oxygen content, mass, type of bonds (rigid versus rotatable), and shape as main properties of the molecules and studied their effect on the propensity of these structures to form homo-molecular and hetero-molecular dimers. Using enhanced sampling molecular dynamics techniques, we have computed the free energy of dimerization in the temperature range 500-1680 K. Initial structures used in this study were obtained from experimental data. The results show that although the effects of shape, presence of oxygen, mass, and internal bonds are tightly intertwined, and their relative importance changes with temperature. In general, mass and the presence of rotatable bonds are the best indicators. The results provide knowledge on the inception step and the role that particle characteristics play during inception. In addition, our study highlights the fact that current models that use stabilomers as monomers for physical aggregation are overestimating the importance of this process during particle nucleation. Copyright © 2017, The Authors. All rights reserved.

关键词： Molecular dynamics

Relevance of packing to colloidal self-assembly

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arXiv 2017年

作者： Cersonsky, Rose van Anders, Greg Dodd, Paul M. Glotzer, Sharon C. Macromolecular Science and Engineering Program University of Michigan Ann ArborMI48109 United States Department of Chemical Engineering University of Michigan Ann ArborMI48109 United States Department of Macromolecular Science and Engineering University of Michigan Ann ArborMI48109 United States Department of Materials Science and Engineering University of Michigan Ann ArborMI48109 United States Biointerfaces Institute University of Michigan Ann ArborMI48109 United States

Since the 1920s, packing arguments have been used to rationalize crystal structures in systems ranging from atomic mixtures to colloidal crystals. Packing arguments have recently been applied to complex nanoparticle structures, where they often, but not always, work. We examine when, if ever, packing is a causal mechanism in hard particle approximations of colloidal crystals. We investigate three crystal structures comprised of their ideal packing shapes. We show that, contrary to expectations, the ordering mechanism cannot be packing, even when the thermodynamically self-assembled structure is the same as that of the densest packing. We also show that the best particle shapes for hard particle colloidal crystals in the infinite pressure limit are imperfect versions of the ideal packing shape. Copyright © 2017, The Authors. All rights reserved.

关键词： Crystal atomic structure

LED Lights with Hidden Intensity-Modulated Blue Channels Aiming for Enhanced Subconscious Visual Responses

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IEEE Photonics Journal

IEEE Photonics Journal 2017年第3期9卷 8201009页

作者： Vartanian, Garen Wong, Kwoon Y. Ku, Pei-Cheng Macromolecular Science and Engineering Graduate Program University of Michigan Ann ArborMI48109 United States Department of Ophthalmology and Visual Sciences University of Michigan Ann ArborMI48109 United States Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States

A new form of light-emitting diode (LED) light suitable for general illumination is proposed to enhance subconscious, nonimage-forming visual responses, which are essential to our well-being. Pulsing light has been shown to reduce photoreceptor adaptation and elicit stronger subconscious visual responses at an indoor illumination level. Using the silent substitution technique, a melanopsin-selective flicker can be added into white light. A linear optimization algorithm was developed to suppress any perceivable fluctuation of light intensity and colors of illuminated objects. Two examples of lights are given to illustrate the potential applications of the proposed multi-LED light for general illumination and therapeutic purposes. © 2009-2012 IEEE.

关键词： Light emitting diodes

A New Data-Driven Sparse-Learning Approach to Study Chemical Reaction Networks

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arXiv 2017年

作者： Harirchi, Farshad Kim, Doohyun Khalil, Omar Liu, Sijia Elvati, Paolo Hero, Alfred Violi, Angela Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2125 United States Department of Mechanical Engineering University of Michigan Ann ArborMI48109-2125 United States Biophysics Program Departments of Chemical Engineering Biomedical Engineering Macromolecular Science and Engineering University of Michigan Ann ArborMI48109-2125 United States

Chemical kinetic mechanisms can be represented by sets of elementary reactions that are easily translated into mathematical terms using physicochemical relationships. The schematic representation of reactions captures the interactions between reacting species and products. Determining the minimal chemical interactions underlying the dynamic behavior of systems is a major task. In this paper, we introduce a novel approach for the identification of the inuential reactions in chemical reaction networks for combustion applications, using a data-driven sparse-learning technique. The proposed approach identifies a set of inuential reactions using species concentrations and reaction rates, with minimal computational cost without requiring additional data or simulations. The new approach is applied to analyze the combustion chemistry of H2andC3H8in a constant-volume homogeneous reactor. The inuential reactions identified by the sparse-learning method are consistent with the current kinetics knowledge of chemical mechanisms. Additionally, we show that a reduced version of the parent mechanism can be generated as a combination of the inuential reactions identified at different times and conditions and that for both H2andC3H8this reduced mechanism performs closely to the parent mechanism as a function of ignition delay over a wide range of conditions. Our results demonstrate the potential of the sparse-learning approach as an effective and efficient tool for mechanism analysis and mechanism reduction. Copyright © 2017, The Authors. All rights reserved.

关键词： Learning systems

Dendritic platinum-copper bimetallic nanoassemblies with tunable composition and structure： Arginine-driven self-assembly and enhanced electrocatalytic activity

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Nano Research 2016年第3期9卷 755-765页

作者： Gengtao Fu Huimin Liu Nika You Jiayan Wu Dongmei Sun Lin Xu Yawen Tang Yu Chen Key Laboratory of Macromolecular Science of Shaanxi Province School of Materials Science and Engineering Shaanxi Normal University Xi'an 710062 China Jiangsu Key Laboratory of New Power Batteries Jiangsu Collaborative Innovation Centre of Biomedical Functional Materials School ot Chemistry and Materials Science Nanjing Normal University Nanjing 210023 China Materials Science and Engineering Program & Texas Materials Institute The University of Texas atAustin Austin Texas 78712 USA

Novel self-assembled architectures have received a growing amount of attention and have significant potential for application in catalysis/electrocatalysis. Herein, we take advantage of the unique coordination and self-assembly properties of arginine for the preparation of dendritic PtCu bimetallic nanoassemblies with tunable chemical composition and structure. Strong interactions between the arginine molecules are key in driving the self-assembly of primary nanocrystals. In addition, the strong coordination interactions between arginine and metal ions is responsible for the formation of Pt-Cu alloys. We also investigated the electrocatalytic activity of various dendritic PtCu bimetallic nanoassemblies towards the methanol oxidation reaction. PtBCUl nanoassemblies exhibited excellent electrocatalytic activity and stability in comparison with other PtCu bimetallic nanoassemblies （PtlCu3, PtlCu~） and commercial Pt black, due to their unique dendritic structures and the synergistic effect between the Pt and Cu atoms.

关键词： platinum-copper nanoassemblies arginine molecules electrocatalysis methanol oxidation