18 results on '"Matthew D. Goodman"'
Search Results
2. Synthesis and formation mechanism of all-organic block copolymer-directed templating of laser-induced crystalline silicon nanostructures
- Author
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Paul V. Braun, Hiroaki Sai, Jörg G. Werner, Matthew D. Goodman, Michael Thompson, Ha Seong Kim, Kwan Wee Tan, Ulrich Wiesner, Byungki Jung, and School of Materials Science and Engineering
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Amorphous silicon ,Nanostructure ,Materials science ,Silicon ,Laser Heating ,technology, industry, and agriculture ,chemistry.chemical_element ,02 engineering and technology ,Chemical vapor deposition ,Self-assembly ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Materials::Nanostructured materials [Engineering] ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Copolymer ,General Materials Science ,Crystalline silicon ,0210 nano-technology ,Mesoporous material - Abstract
This report describes the generation of three-dimensional (3D) crystalline silicon continuous network nanostructures by coupling all-organic block copolymer self-assembly-directed resin templates with low-temperature silicon chemical vapor deposition and pulsed excimer laser annealing. Organic 3D mesoporous continuous-network resin templates were synthesized from the all-organic self-assembly of an ABC triblock terpolymer and resorcinol–formaldehyde resols. Nanosecond pulsed excimer laser irradiation induced the transient melt transformation of amorphous silicon precursors backfilled in the organic template into complementary 3D mesoporous crystalline silicon nanostructures with high pattern fidelity. Mechanistic studies on laser-induced crystalline silicon nanostructure formation revealed that the resin template was carbonized during transient laser-induced heating on the milli- to nanosecond timescales, thereby imparting enhanced thermal and structural stability to support the silicon melt–crystallization process at temperatures above 1250 °C. Photoablation of the resin material under pulsed excimer laser irradiation was mitigated by depositing an amorphous silicon overlayer on the resin template. This approach represents a potential pathway from organic block copolymer self-assembly to alternative functional hard materials with well-ordered 3D morphologies for potential hybrid photovoltaics, photonic, and energy storage applications. MOE (Min. of Education, S’pore) Accepted version
- Published
- 2018
3. Enhanced Secondary Battery Anodes Based on Si and Fe3 O4 Nanoparticle Infilled Monodisperse Carbon Starburst Colloidal Crystals
- Author
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Paul V. Braun, Sanghyeon Kim, Narihito Tatsuda, Matthew D. Goodman, and Kazuhisa Yano
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Battery (electricity) ,Materials science ,Dispersity ,chemistry.chemical_element ,Nanotechnology ,General Chemistry ,Colloidal crystal ,Condensed Matter Physics ,Anode ,Porous carbon ,chemistry ,General Materials Science ,Self-assembly ,Carbon ,Fe3o4 nanoparticles - Published
- 2015
4. Enabling New Classes of Templated Materials through Mesoporous Carbon Colloidal Crystals
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Paul V. Braun, Kevin A. Arpin, Kazuhisa Yano, Matthew D. Goodman, Agustín Mihi, and Narihito Tatsuda
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chemistry.chemical_classification ,Materials science ,Fabrication ,Nanotechnology ,Polymer ,Colloidal crystal ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Dye-sensitized solar cell ,Colloid ,Template ,chemistry ,Deposition (phase transition) ,Polystyrene - Abstract
Colloidal crystals have attracted considerable attention due to their deterministic three-dimensional (3D) structures, interesting optical properties and ease of assembly. [ 1–5 ] The use of colloidal crystals as templates to impart periodic patterns into various materials has been broadly employed to create, for example, unique optoelectronic devices, [ 6,7 ] sensors, [ 8–12 ] and energy storage devices. [ 13,14 ] The general motivation for templating is to utilize the opals’ interconnected 3D structure to defi ne the 3D structure of a material which is inherently diffi cult to form into a highly regular 3D structure on its own. A single replication yields a structure which is an inverse of the colloidal template, and a double replication yields the original structure of the template. This process is only successful if the colloidal template can withstand the deposition conditions of the material to be templated and there exist conditions whereby the original template can be removed without damaging the templated material. Given that the most popular template, silica, can only be removed with hydrofl uoric acid or strong base, chemicals that dissolve many materials, this can be challenging. Polymer templates (e.g. polystyrene or poly(methyl methacrylate)) are easy to remove, but cannot withstand high temperature deposition strategies, limiting their use. [ 2 ] Thermally-stable colloids which could be removed under orthogonal conditions, i.e., conditions that do not damage the templated material, would allow currently inaccessible materials templating strategies. Additionally, if the templates contained additional desirable structural complexities (e.g. a high surface area) which are replicated in the templated material, additional applications may emerge; for example, dye sensitized solar cells require high-surface area electrodes, [ 15 ] as do many other catalytic devices. In this communication, we fi rst demonstrate the fabrication of high-quality
- Published
- 2013
5. Graphene Sandwiched Mesostructured Li-Ion Battery Electrodes
- Author
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Mauricio Terrones, Xing-Jiu Huang, Paul V. Braun, Haoyue Zhu, Neil A. Krueger, Hailong Ning, Jinyun Liu, Jinwoo Kim, Matthew D. Goodman, Jinhuai Liu, and Qiye Zheng
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Battery (electricity) ,Materials science ,business.industry ,Graphene ,Mechanical Engineering ,Graphene foam ,Inorganic chemistry ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cathode ,0104 chemical sciences ,law.invention ,Ion ,Anode ,Nanomaterials ,Mechanics of Materials ,law ,Electrode ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business - Abstract
A deterministic graphene-sandwiched Li-ion battery electrode consisting of an integrated 3D mesostructure of electrochemically active materials and graphene is presented. As demonstrations, electrodes with active nanomaterials that coat (V2 O5 @graphene@V2 O5 cathode) or are coated by (graphene@Si@graphene anode) graphene are fabricated. These electrodes exhibit high capacities and ultralong cycle lives (the cathode can be cycled over 2000 times with minimal capacity fade).
- Published
- 2016
6. Self-Assembly of CdTe Tetrapods into Network Monolayers at the Air/Water Interface
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Surya K. Mallapragada, Zhiqun Lin, Karen A. DeRocher, Lei Zhao, Matthew D. Goodman, and Jun Wang
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Models, Molecular ,Materials science ,Band gap ,Air ,Ribbon diagram ,Molecular Conformation ,General Engineering ,Water ,General Physics and Astronomy ,Nanotechnology ,Microscopy, Atomic Force ,Surface pressure ,Langmuir–Blodgett film ,Cadmium telluride photovoltaics ,Absorption ,Electron Transport ,Microscopy, Electron, Transmission ,Chemical engineering ,Monolayer ,Cadmium Compounds ,General Materials Science ,Dewetting ,Tellurium ,Deposition (law) - Abstract
Cadmium telluride (CdTe) tetrapods are synthesized with varying aspect ratios through multiple injections of the Te precursor, which provides an excellent means of controlling and tailoring the optical properties of the tetrapods. The self-assembly of CdTe tetrapods at the air/water interface is explored using the Langmuir-Blodgett (LB) technique due to potential use in solar cells arising from the intriguing tetrapod shape that improves charge transport and the optimum band gap energy of CdTe that enhances light absorption. Interestingly, the Langmuir isotherm shows two pressure plateau regions: one at approximately 10 mN/m with the other at the high surface pressure of approximately 39 mN/m. LB deposition at various pressures allows the discernment of the unique two-dimensional packing alluded in the isotherm. By placing CdTe at the air/water interface, it is revealed in the deposition that the tetrapods experienced a dewetting phenomenon, forming a ribbon structure at the onset of surface pressure with a height corresponding to the length of one tetrapod arm. With the increase of surface pressure, the ribbons widen to an eventual large-scale percolated network pattern. The packing density of tetrapods is successfully manipulated by controlling the surface pressure, which may find promising applications in optoelectronic devices.
- Published
- 2010
7. Semiconductor Conjugated Polymer−Quantum Dot Nanocomposites at the Air/Water Interface and Their Photovoltaic Performance
- Author
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Jun Xu, Jun Wang, Zhiqun Lin, and Matthew D. Goodman
- Subjects
chemistry.chemical_classification ,Langmuir ,Materials science ,Nanocomposite ,business.industry ,General Chemical Engineering ,Nanotechnology ,General Chemistry ,Polymer ,Active layer ,Semiconductor ,chemistry ,Chemical engineering ,Quantum dot ,Materials Chemistry ,Thin film ,business ,Short circuit - Abstract
Organic−inorganic nanocomposites consisting of electroactive conjugated polymer, poly(3-hexylthiophene) (P3HT), intimately tethered on the surface of semiconductor CdSe quantum dot (i.e., P3HT−CdSe nanocomposites) at the air/water interface formed via Langmuir isotherms were explored for the first time. The P3HT−CdSe nanocomposites displayed a high pressure plateau (∼10.5 mN/m) in the Langmuir isotherm, illustrating their complex packing at the air/water interface. The packing of the Langmuir−Blodgett (LB) depositions of nanocomposites was revealed by AFM measurements. Furthermore, photovoltaic devices fabricated from the LB depositions of the P3HT−CdSe nanocomposites exhibited a relatively high short circuit current, ISC, while maintaining a thin film profile. These studies provide insights into the fundamental behaviors of semiconductor organic−inorganic nanocomposites confined at the air/water interface as well as in the active layer of an organic-based photovoltaic device.
- Published
- 2009
8. Self-assembly of monodisperse starburst carbon spheres into hierarchically organized nanostructured supercapacitor electrodes
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Paul V. Braun, Narihito Tatsuda, Euiyeon Jung, Kenneth S. Schweizer, Sung-Kon Kim, Kazuhisa Yano, and Matthew D. Goodman
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Supercapacitor ,Materials science ,chemistry ,Electrode ,chemistry.chemical_element ,General Materials Science ,Nanotechnology ,Self-assembly ,Porosity ,Carbon ,Capacitance ,Microscale chemistry ,Ion - Abstract
We report a three-dimensional (3D) porous carbon electrode containing both nanoscale and microscale porosity, which has been hierarchically organized to provide efficient ion and electron transport. The electrode organization is provided via the colloidal self-assembly of monodisperse starburst carbon spheres (MSCSs). The periodic close-packing of the MSCSs provides continuous pores inside the 3D structure that facilitate ion and electron transport (electrode electrical conductivity ∼0.35 S m(-1)), and the internal meso- and micropores of the MSCS provide a good specific capacitance. The capacitance of the 3D-ordered porous MSCS electrode is ∼58 F g(-1) at 0.58 A g(-1), 48% larger than that of disordered MSCS electrode at the same rate. At 1 A g(-1) the capacitance of the ordered electrode is 57 F g(-1) (95% of the 0.24 A g(-1) value), which is 64% greater than the capacitance of the disordered electrode at the same rate. The ordered electrode preserves 95% of its initial capacitance after 4000 charging/discharging cycles.
- Published
- 2015
9. Mechanically and chemically robust sandwich-structured C@Si@C nanotube array Li-ion battery anodes
- Author
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Jun-hee Choi, K. Jimmy Hsia, Jinhuai Liu, Bo Huang, Shen J. Dillon, Xing-Jiu Huang, Paul V. Braun, Huigang Zhang, Eric S. Epstein, Jinyun Liu, Jinwoo Kim, Nan Li, Matthew D. Goodman, and Zeng Pan
- Subjects
Battery (electricity) ,Nanotube ,Materials science ,Silicon ,General Engineering ,General Physics and Astronomy ,chemistry.chemical_element ,Nanotechnology ,Anode ,Chemical engineering ,chemistry ,Electrode ,General Materials Science ,Chemical stability ,Thin film ,Faraday efficiency - Abstract
Stability and high energy densities are essential qualities for emerging battery electrodes. Because of its high specific capacity, silicon has been considered a promising anode candidate. However, the several-fold volume changes during lithiation and delithiation leads to fractures and continuous formation of an unstable solid-electrolyte interphase (SEI) layer, resulting in rapid capacity decay. Here, we present a carbon-silicon-carbon (C@Si@C) nanotube sandwich structure that addresses the mechanical and chemical stability issues commonly associated with Si anodes. The C@Si@C nanotube array exhibits a capacity of ∼2200 mAh g(-1) (∼750 mAh cm(-3)), which significantly exceeds that of a commercial graphite anode, and a nearly constant Coulombic efficiency of ∼98% over 60 cycles. In addition, the C@Si@C nanotube array gives much better capacity and structure stability compared to the Si nanotubes without carbon coatings, the ZnO@C@Si@C nanorods, a Si thin film on Ni foam, and C@Si and Si@C nanotubes. In situ SEM during cycling shows that the tubes expand both inward and outward upon lithiation, as well as elongate, and then revert back to their initial size and shape after delithiation, suggesting stability during volume changes. The mechanical modeling indicates the overall plastic strain in a nanotube is much less than in a nanorod, which may significantly reduce low-cycle fatigue. The sandwich-structured nanotube design is quite general, and may serve as a guide for many emerging anode and cathode systems.
- Published
- 2015
10. Role of functionalized terminal groups in formation of nanofibrillar morphology of hyperbranched polyesters
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Sergiy Peleshanko, V. V. Shevchenko, Vladimir V. Tsukruk, Maryna Ornatska, Matthew D. Goodman, and Kathryn N. Bergman
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chemistry.chemical_classification ,Morphology (linguistics) ,Polymers and Plastics ,Organic Chemistry ,Polyester ,End-group ,chemistry.chemical_compound ,chemistry ,Amphiphile ,Polymer chemistry ,Monolayer ,Materials Chemistry ,Organic chemistry ,Self-assembly ,Alkyl ,Acyl group - Abstract
A series of amphiphilic hyperbranched polymers with a polyester–polyol core and 64 terminal hydroxyl groups were modified by substituting various terminal groups: alkyl tails, amino, and carboxyl groups. The effect of the pendant groups' chemical composition on the resulting surface morphology within Langmuir–Blodgett monolayers with respect to their ability to form nanofibrillar surface structures was investigated. We demonstrated that the amphiphilicity of the polyester core with 64 hydroxyl groups can be achieved if a fraction of alkyl tails (C15) is higher than 1/4. Nanofibrillar morphology was consistently formed as the highly polar functional groups were added to the polyester cores in combination with a significant (>30%) fraction of alkyl terminal groups. Addition of amino end groups was observed to be much more effective in promoting the nanofibrillar assembly than the addition of carboxyl end groups.
- Published
- 2006
11. Quaternary Structure of Rice Nonsymbiotic Hemoglobin
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Mark S. Hargrove and Matthew D. Goodman
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chemistry.chemical_classification ,Carbon Monoxide ,Hemeprotein ,Chemistry ,Protein subunit ,Oxygen transport ,Hexacoordinate ,Oryza ,Cell Biology ,Biochemistry ,Recombinant Proteins ,Amino acid ,Molecular Weight ,Hemoglobins ,Protein quaternary structure ,Hemoglobin ,Protein Structure, Quaternary ,Dimerization ,Molecular Biology ,Chromatography, High Pressure Liquid ,Histidine ,Plant Proteins - Abstract
Plant nonsymbiotic hemoglobins are hexacoordinate heme proteins found in all plants. Although expression is linked with hypoxic environmental conditions (Taylor, E. R., Nie, X. Z., Alexander, W. M., and Hill, R. D. (1994)Plant Mol. Biol. 24, 853–862), no discrete physiological function has yet been attributed to this family of proteins. The crystal structure of a nonsymbiotic hemoglobin from rice has recently been determined. The crystalline protein is homodimeric and hexacoordinate with two histidine side chains coordinating the heme iron atom. Despite the fact that the amino acids responsible for the subunit interface are relatively conserved among the nonsymbiotic hemoglobins, previous work suggests that this group of proteins might display variability in quaternary structure (Duff, S. M. G., Wittenberg, J. B., and Hill , R. D. (1997) J. Biol. Chem. 272, 16746–16752; Arredondo-Peter, R., Hargrove, M. S., Sarath, G., Moran, J. F., Lohrman, J., Olson, J. S., and Klucas , R. V. (1997) Plant Physiol. 115, 1259–1266). Analytical ultracentrifugation and size exclusion high pressure liquid chromatography were used to investigate the quaternary structure of rice nonsymbiotic hemoglobin at various states of ligation and oxidation. Additionally, site-directed mutagenesis was used to test the role of several interface amino acids in dimer formation and ligand binding. Results were analyzed in light of possible physiological functions and indicate that the plant nonsymbiotic hemoglobins are not oxygen transport proteins but more closely resemble known oxygen sensors.
- Published
- 2001
12. Lithium-Ion Batteries: Graphene Sandwiched Mesostructured Li-Ion Battery Electrodes (Adv. Mater. 35/2016)
- Author
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Jinwoo Kim, Qiye Zheng, Paul V. Braun, Xing-Jiu Huang, Neil A. Krueger, Hailong Ning, Jinyun Liu, Jinhuai Liu, Matthew D. Goodman, Mauricio Terrones, and Haoyue Zhu
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Battery (electricity) ,Materials science ,Graphene ,Mechanical Engineering ,Inorganic chemistry ,Graphene foam ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cathode ,0104 chemical sciences ,law.invention ,Anode ,chemistry ,Mechanics of Materials ,law ,Electrode ,General Materials Science ,Lithium ,Nanoarchitectures for lithium-ion batteries ,0210 nano-technology - Published
- 2016
13. Synthesis of a Novel Photopolymerized Nanocomposite Hydrogel for Treatment of Acute Mechanical Damage to Cartilage
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Zhiqun Lin, Xunpei Liu, James A. Martin, Tanya Prozorov, Robert J. Lipert, Matthew D. Goodman, Kathryn Schlichting, Trishelle M. Copeland-Johnson, Surya K. Mallapragada, and Todd O. McKinley
- Subjects
Cartilage, Articular ,Materials science ,Compressive Strength ,Light ,Biomedical Engineering ,Osteoarthritis ,Biochemistry ,Article ,Hydrogel, Polyethylene Glycol Dimethacrylate ,Nanocomposites ,Polymerization ,Biomaterials ,Tensile Strength ,Ultimate tensile strength ,Materials Testing ,medicine ,Animals ,Composite material ,Particle Size ,Molecular Biology ,Nanocomposite ,Cartilage ,Structural integrity ,Biomaterial ,General Medicine ,Adhesion ,medicine.disease ,Tibial Fractures ,medicine.anatomical_structure ,Cattle ,Shear Strength ,Shear testing ,Biotechnology ,Biomedical engineering - Abstract
Intra-articular fractures initiate a cascade of pathobiological and pathomechanical events that culminate in post-traumatic osteoarthritis (PTOA). Hallmark features of PTOA include destruction of the cartilage matrix in combination with loss of chondrocytes and acute mechanical damage (AMD). Currently, treatment of intra-articular fractures essentially focuses completely on restoration of the macroanatomy of the joint. However, current treatment ignores AMD sustained by cartilage at the time of injury. We are exploring aggressive biomaterial-based interventions designed to treat the primary pathological components of AMD. This study describes the development of a novel injectable co-polymer solution that forms a gel at physiological temperatures that can be photocrosslinked, and can form a nanocomposite gel in situ through mineralization. The injectable co-polymer solution will allow the material to fill cracks in the cartilage after trauma. The mechanical properties of the nanocomposite are similar to those of native cartilage, as measured by compressive and shear testing. It thereby has the potential to mechanically stabilize and restore local structural integrity to acutely injured cartilage. Additionally, in situ mineralization ensures good adhesion between the biomaterial and cartilage at the interface, as measured through tensile and shear testing. Thus we have successfully developed a new injectable co-polymer which forms a nanocomposite in situ with mechanical properties similar to those of native cartilage, and which can bond well to native cartilage. This material has the potential to stabilize injured cartilage and prevent PTOA.
- Published
- 2011
14. Mechanically Robust Sandwich-Structured C@Si@C Nanotube-Based Li-Ion Battery Anodes
- Author
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Jinyun Liu, Matthew D. Goodman, Hui Gang Zhang, Eric S. Epstein, Bo Huang, Zeng Pan, Jinwoo Kim, Junhee Choi, Xingjiu Huang, Jinhuai Liu, Nan Li, K. Jimmy Hsia, Shen J. Dillon, and Paul V Braun
- Abstract
Advanced secondary (rechargeable) batteries require high energy density and high structural stability anodes and cathodes. High volumetric energy density is particularly desirable for micro-electronic devices and portable applications, however it can impact almost any application. In current commercial lithium-ion batteries, carbon-based anodes are dominant; however, their capacity and structural stability are not ideal due to the low theoretical capacity (372 mAh g‒1) and intrinsically fragile structure of carbon. Silicon is a very attractive anode material because of its huge theoretical capacity (~4,200 mAh g‒1). Nevertheless, the solid electrolyte interphase (SEI) formation on Si surface is generally unstable due to the large volume change during lithiation-delithiation (400%), which leads to substantial capacity decay with cycling. Here we present an anode design consisting of closed-end Si nanotubes coated with carbon on both sides (C@Si@C). This sandwich-like structure with double-sided carbon coatings provides both good electrical conductivity and effective protection of electrochemically active Si, leading to a stable SEI. Because the C@Si@C nanotube array was fabricated onto a three-dimensional (3D) scaffold, the anode exhibits a considerable energy density. Our results show this nanotube array exhibits a capacity of about 2,200 mAh g-1, and a nearly constant Coulombic efficiency of about 98% over 60 cycles. Correspondingly, the volumetric energy density (~750 mAh cm–3) considerably exceeds the volumetric energy density of commercial graphite anodes (~300 mAh cm–3). Through a series of control experiments, we find the C@Si@C nanotube array gives much better capacity and structure stability compared to the Si nanotubes without carbon coatings, the ZnO@C@Si@C nanorods, a Si thin film on Ni foam, and C@Si and Si@C nanotubes. In-situ SEM observations on lithiation-delithiation shows a stable structure evolution of the sandwich nanotube. Through stress and plastic strain modeling, while the plastic strain in the nanotubes increases gently, the one in the nanorods increases dramatically. Since the plastic strain amplitude in the nanorods is significantly higher than that in the nanotubes, in terms of a low-cycle fatigue mechanism of Si during lithiation-delithiation, it is expected that the nanorods would fail with significantly fewer lithiation-delithiation cycles compared to the nanotubes. Our findings show this design of sandwich-structured nanotube array is effective for fabricating anodes with both stable structure retention and high energy density. We believe this strategy is quite general can find application for a large variety of other anode and cathode designs.
- Published
- 2015
15. Self-assembly of an ultra-high-molecular-weight comb block copolymer at the air–water interface
- Author
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Matthew D. Goodman, Lei Zhao, Ned B. Bowden, and Zhiqun Lin
- Subjects
Materials science ,General Chemistry ,Condensed Matter Physics ,Surface pressure ,Toluene ,Solvent ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Amphiphile ,Polymer chemistry ,Copolymer ,Dewetting ,Self-assembly ,Polystyrene - Abstract
The self-assembly of a newly synthesized, amphiphilic comb block copolymer (CBCP) at the air–water interface was systematically explored using the Langmuir–Blodgett (LB) technique. The CBCP had an ultra-high molecular weight (Mw = 510 × 103 g mol−1) with polystyrene arms grafted along one block of long hydrophilic backbone. At the air–water interface, the CBCP molecules spontaneously assembled into ribbon-like structures and cellular patterns at zero surface pressure when a volatile solvent (i.e., chloroform) and a less volatile solvent (i.e., toluene) were used, respectively. This spontaneous self-assembly behavior of the CBCP was induced by the dewetting process. The mechanism for the morphological change as a function of surface pressure was scrutinized and further confirmed by compression–expansion cycle and solvent vapor annealing studies. To the best of our knowledge, this is the first study of self-assembly of ultra-high-molecular-weight, amphiphilic CBCPs at the air–water interface. As such, it provides insight into the design of controllable pattern formation using amphiphilic copolymers.
- Published
- 2009
16. A simple biphasic route to water soluble dithiocarbamate functionalized quantum dots
- Author
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Joseph Shinar, Zhiqun Lin, Jun Wang, Jun Xu, Matthew D. Goodman, Min Cai, and Ying Chen
- Subjects
chemistry.chemical_classification ,Aqueous solution ,Ion exchange ,Chemistry ,Ligand ,Inorganic chemistry ,technology, industry, and agriculture ,Trioctylphosphine ,Nanoparticle ,Quantum yield ,General Chemistry ,equipment and supplies ,Photochemistry ,chemistry.chemical_compound ,Quantum dot ,Materials Chemistry ,Dithiocarbamate - Abstract
Hydrophobic trioctylphosphine oxide-functionalized CdSe quantum dots (CdSe-TOPO QDs) were transferred from organic solvent to aqueous solution via a simple yet novel biphasic ligand exchange process in one step, which involved the in-situ formation of hydrophilic dithiocarbamate moieties and subsequent ligand exchange with TOPO at the chloroform/water interface. The resulting water dispersible, dithiocarbamate functionalized CdSe QDs (i.e., D-CdSe) exhibited an increased photoluminescence (PL) quantum yield as compared to the original CdSe-TOPO QDs, suggesting an effective passivation of dithiocarbamate ligands on the QD surface. The D-CdSe QDs were then mixed with hydroxyl terminated TiO2nanoparticles. A decrease in the PL of the mixture was observed, indicating a possible charge transfer from the D-CdSe QDs to the TiO2nanoparticles. The reaction of the carboxyl group on the D-CdSe surface with the hydroxyl group on the TiO2 rendered QDs in direct contact with TiO2, thereby facilitating the electronic interaction between them.
- Published
- 2008
17. Semiconductor Conjugated Polymer−Quantum Dot Nanocomposites at the Air/Water Interface and Their Photovoltaic Performance.
- Author
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Matthew D. Goodman, Jun Xu, Jun Wang, and Zhiqun Lin
- Subjects
- *
SEMICONDUCTORS , *CONJUGATED polymers , *QUANTUM dots , *NANOCOMPOSITE materials , *WATER , *PHOTOVOLTAIC power generation , *THIOPHENES , *CADMIUM selenide - Abstract
Organic−inorganic nanocomposites consisting of electroactive conjugated polymer, poly(3-hexylthiophene) (P3HT), intimately tethered on the surface of semiconductor CdSe quantum dot (i.e., P3HT−CdSe nanocomposites) at the air/water interface formed via Langmuir isotherms were explored for the first time. The P3HT−CdSe nanocomposites displayed a high pressure plateau (∼10.5 mN/m) in the Langmuir isotherm, illustrating their complex packing at the air/water interface. The packing of the Langmuir−Blodgett (LB) depositions of nanocomposites was revealed by AFM measurements. Furthermore, photovoltaic devices fabricated from the LB depositions of the P3HT−CdSe nanocomposites exhibited a relatively high short circuit current, ISC, while maintaining a thin film profile. These studies provide insights into the fundamental behaviors of semiconductor organic−inorganic nanocomposites confined at the air/water interface as well as in the active layer of an organic-based photovoltaic device. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
18. A simple biphasic route to water soluble dithiocarbamate functionalized quantum dots.
- Author
-
Jun Wang, Jun Xu, Matthew D. Goodman, Ying Chen, Min Cai, Joseph Shinar, and Zhiqun Lin
- Abstract
Hydrophobic trioctylphosphine oxide-functionalized CdSe quantum dots (CdSe-TOPO QDs) were transferred from organic solvent to aqueous solution via a simple yet novel biphasic ligand exchange process in one step, which involved the in-situ formation of hydrophilic dithiocarbamate moieties and subsequent ligand exchange with TOPO at the chloroform/water interface. The resulting water dispersible, dithiocarbamate functionalized CdSe QDs (i.e., D-CdSe) exhibited an increased photoluminescence (PL) quantum yield as compared to the original CdSe-TOPO QDs, suggesting an effective passivation of dithiocarbamate ligands on the QD surface. The D-CdSe QDs were then mixed with hydroxyl terminated TiO2 nanoparticles. A decrease in the PL of the mixture was observed, indicating a possible charge transfer from the D-CdSe QDs to the TiO2 nanoparticles. The reaction of the carboxyl group on the D-CdSe surface with the hydroxyl group on the TiO2 rendered QDs in direct contact with TiO2, thereby facilitating the electronic interaction between them. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
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