Abstract Carbon Nanotube (CNT) membranes were shown to offer great potential for separation appli... more Abstract Carbon Nanotube (CNT) membranes were shown to offer great potential for separation applications due to their attractive physicochemical, mechanical, thermal and electrical properties. This paper provides a critical review on the fabrication methods, properties and applications of CNT membranes and discusses the main challenges in both scaled-up production and advanced separation application for liquid and gas filtration. This review extends to offer in-depth insights on three main categories of CNT membranes, including vertically aligned (VA), mixed matrix (MM) and bucky paper (BP) CNT membranes. The impact of CNT structure on the membrane properties and performance is explained with highlighting multiple key parameters, such as CNT alignment, packing density and surface functionalization. The main challenge is how to integrate CNTs with their unique properties into a robust membrane structure with outstanding separation performance. This paper therefore deliberates novel trends of CNT membrane fabrication and their limitations in detail, followed by a thorough discussion on applying these CNT membranes in not only water treatment but also liquid and gas separation. Finally, concise challenges and prospects are outlined towards scaled-up production and commercialization of CNT membranes to highlight promising solutions for designing high-performance CNT membranes for advanced separation applications.
Twisting is cool Rubber bands that are stretched and held in an extended shape for a while will e... more Twisting is cool Rubber bands that are stretched and held in an extended shape for a while will extract heat from their surroundings as they are allowed to relax, owing to a reversal of stress-induced crystallization, which is an exothermic process. Wang et al. examine the potential for solid-state cooling of twisted fibers, along with configurations such as supercoiling, for materials including natural rubber, polyethylene, and nickel-titanium fibers. The cooling is related to the change in entropy of the material as it is mechanically deformed. Science , this issue p. 216
Most polydiacetylenes (PDAs) have been studied as chromatic sensors or temperature indicators bec... more Most polydiacetylenes (PDAs) have been studied as chromatic sensors or temperature indicators because of their phase transition that is accompanied by a color change from blue to red. Here, we focus on the structural change based on the polydiacetylene phase transition for a temperature-responsive tensile actuator at low temperature using a copolymer composed of PDA and pluronic in a multi-walled carbon nanotube (MWCNT) coiled yarn. In this paper, we do not focus on the general color change phenomenon of PDA. We demonstrate that the volume change of PDA in the MWCNT coiled yarn provides ~180% tensile strain at low temperature (~53 °C). Insertion of the pluronic copolymer into the coiled yarn composed of PDA and MWCNT caused the tensile actuation temperature to decrease by ~6 °C (with tensile actuation of ~230%) compared to an actuator without pluronic copolymer. Furthermore, we could verify that the large tensile actuation was also predominantly affected by the melting of the nonpolymerized diacetylene (DA) monomer and the pluronic copolymer. MWCNT coiled yarn actuators with PDA-pluronic copolymer can be easily prepared, have a large tensile actuation, and are actuated at low temperature. It could be used as temperature indicators in the food, drugs, and medical fields.
A highly stretchable all-solid-state supercapacitor is fabricated by using PEDOT/carbon nanotube ... more A highly stretchable all-solid-state supercapacitor is fabricated by using PEDOT/carbon nanotube sheet hybrid nanomembrane. It exhibited high energy density (7.28–6.87 W h kg−1) and stretchability (up to biaxial strain of 600%).
Mediator-free, microsized yarn biofuel cells are made by simple self-assembly. This system can pr... more Mediator-free, microsized yarn biofuel cells are made by simple self-assembly. This system can provide power density up to 236 mW cm−2and an open circuit voltage of 0.61 V. The system maintained 84% of its initial power for 20 days.
Small (Weinheim an der Bergstrasse, Germany), 2016
Boronic acid (BA), known to be a reversible glucose-sensing material, is conjugated to a nanogel ... more Boronic acid (BA), known to be a reversible glucose-sensing material, is conjugated to a nanogel (NG) derived from hyaluronic acid biopolymer and used as a guest material for a carbon multiwalled nanotube (MWNT) yarn. By exploiting the swelling/deswelling of the NG that originates from the internal anionic charge changes resulting from BA binding to glucose, a NG MWNT yarn artificial muscle is obtained that provides reversible torsional actuation that can be used for glucose sensing. This actuator shows a short response time and high sensitivity (in the 5-100 × 10(-3) m range) for monitoring changes in glucose concentration in physiological buffer, without using any additional auxiliary substances or an electrical power source. It may be possible to apply the glucose-sensing MWNT yarn muscles as implantable glucose sensors that automatically release drugs when needed or as an artificial pancreas.
Biomolecule responsive materials have been studied intensively for use in biomedical applications... more Biomolecule responsive materials have been studied intensively for use in biomedical applications as smart systems because of their unique property of responding to specific biomolecules under mild conditions. However, these materials have some challenging drawbacks that limit further practical application, including their speed of response and mechanical properties, because most are based on hydrogels. Here, we present a fast, mechanically robust biscrolled twist-spun carbon nanotube yarn as a torsional artificial muscle through entrapping an enzyme linked to a thermally sensitive hydrogel, poly(N-isopropylacrylamide), utilizing the exothermic catalytic reaction of the enzyme. The induced rotation reached an equilibrated angle in less than 2 min under mild temperature conditions (25-37 °C) while maintaining the mechanical properties originating from the carbon nanotubes. This biothermal sensing of a torsional artificial muscle offers a versatile platform for the recognition of vari...
Torsional behaviors of polymer-infiltrated carbon nanotube (CNT) yarn muscles have been investiga... more Torsional behaviors of polymer-infiltrated carbon nanotube (CNT) yarn muscles have been investigated in relation to molecular architecture by using atomic force microscopy (AFM). Two polymers with different stiffnesses, polystyrene (PS) and poly(styrene-b-isoprene-b-styrene) (SIS), were uniformly infiltrated into CNT yarns for electrothermal torsional actuation. The torsional behaviors of hybrid yarn muscles are completely explained by the volume change of each polymer, based on the height and full width at half maximum profiles from the AFM morphological images. The volume expansion of the PS yarn muscle (1.7 nm of vertical change and 22 nm of horizontal change) is much larger than that of the SIS yarn muscle (0.3 nm and 11 nm change in vertical and horizontal directions) at 80 °C, normalized by their values at 25 °C. We demonstrate that their maximum rotations are consequently 29.7 deg mm(-1) for the PS-infiltrated CNT yarn muscle (relatively larger rotation) and 14.4 deg mm(-1) f...
Improved electrically powered artificial muscles are needed for generating force, moving objects,... more Improved electrically powered artificial muscles are needed for generating force, moving objects, and accomplishing work. Carbon nanotube aerogel sheets are the sole component of new artificial muscles that provide giant elongations and elongation rates of 220% and (3.7 × 10 4 )% per second, respectively, at operating temperatures from 80 to 1900 kelvin. These solid-state–fabricated sheets are enthalpic rubbers having gaslike density and specific strength in one direction higher than those of steel plate. Actuation decreases nanotube aerogel density and can be permanently frozen for such device applications as transparent electrodes. Poisson's ratios reach 15, a factor of 30 higher than for conventional rubbers. These giant Poisson's ratios explain the observed opposite sign of width and length actuation and result in rare properties: negative linear compressibility and stretch densification.
The production of magnesium–chromium oxides by solution combustion synthesis was investigated usi... more The production of magnesium–chromium oxides by solution combustion synthesis was investigated using glycine and urea for the first time. Ammonium dichromate, urea/glycine and ammonium nitrate aqueous solutions were used as the precursors of the oxides. The effect of different reaction parameters, such as fuel richness, stoichiometry and fuel leanness was evaluated; such parameters were modified by changing the reagents and
The synthesis of chromium oxides by solution combustion synthesis was investigated. Ammonium dich... more The synthesis of chromium oxides by solution combustion synthesis was investigated. Ammonium dichromate, glycine, urea and ammonium nitrate dissolved in aqueous solution were used as the precursors of the oxides. The effect of different reaction parameters, such as fuel richness, stoichiometry and fuel leanness was evaluated; such parameters were modified by changing the reagents and the fuel/oxidant ratio. Amorphous CrO3
Abstract Carbon Nanotube (CNT) membranes were shown to offer great potential for separation appli... more Abstract Carbon Nanotube (CNT) membranes were shown to offer great potential for separation applications due to their attractive physicochemical, mechanical, thermal and electrical properties. This paper provides a critical review on the fabrication methods, properties and applications of CNT membranes and discusses the main challenges in both scaled-up production and advanced separation application for liquid and gas filtration. This review extends to offer in-depth insights on three main categories of CNT membranes, including vertically aligned (VA), mixed matrix (MM) and bucky paper (BP) CNT membranes. The impact of CNT structure on the membrane properties and performance is explained with highlighting multiple key parameters, such as CNT alignment, packing density and surface functionalization. The main challenge is how to integrate CNTs with their unique properties into a robust membrane structure with outstanding separation performance. This paper therefore deliberates novel trends of CNT membrane fabrication and their limitations in detail, followed by a thorough discussion on applying these CNT membranes in not only water treatment but also liquid and gas separation. Finally, concise challenges and prospects are outlined towards scaled-up production and commercialization of CNT membranes to highlight promising solutions for designing high-performance CNT membranes for advanced separation applications.
Twisting is cool Rubber bands that are stretched and held in an extended shape for a while will e... more Twisting is cool Rubber bands that are stretched and held in an extended shape for a while will extract heat from their surroundings as they are allowed to relax, owing to a reversal of stress-induced crystallization, which is an exothermic process. Wang et al. examine the potential for solid-state cooling of twisted fibers, along with configurations such as supercoiling, for materials including natural rubber, polyethylene, and nickel-titanium fibers. The cooling is related to the change in entropy of the material as it is mechanically deformed. Science , this issue p. 216
Most polydiacetylenes (PDAs) have been studied as chromatic sensors or temperature indicators bec... more Most polydiacetylenes (PDAs) have been studied as chromatic sensors or temperature indicators because of their phase transition that is accompanied by a color change from blue to red. Here, we focus on the structural change based on the polydiacetylene phase transition for a temperature-responsive tensile actuator at low temperature using a copolymer composed of PDA and pluronic in a multi-walled carbon nanotube (MWCNT) coiled yarn. In this paper, we do not focus on the general color change phenomenon of PDA. We demonstrate that the volume change of PDA in the MWCNT coiled yarn provides ~180% tensile strain at low temperature (~53 °C). Insertion of the pluronic copolymer into the coiled yarn composed of PDA and MWCNT caused the tensile actuation temperature to decrease by ~6 °C (with tensile actuation of ~230%) compared to an actuator without pluronic copolymer. Furthermore, we could verify that the large tensile actuation was also predominantly affected by the melting of the nonpolymerized diacetylene (DA) monomer and the pluronic copolymer. MWCNT coiled yarn actuators with PDA-pluronic copolymer can be easily prepared, have a large tensile actuation, and are actuated at low temperature. It could be used as temperature indicators in the food, drugs, and medical fields.
A highly stretchable all-solid-state supercapacitor is fabricated by using PEDOT/carbon nanotube ... more A highly stretchable all-solid-state supercapacitor is fabricated by using PEDOT/carbon nanotube sheet hybrid nanomembrane. It exhibited high energy density (7.28–6.87 W h kg−1) and stretchability (up to biaxial strain of 600%).
Mediator-free, microsized yarn biofuel cells are made by simple self-assembly. This system can pr... more Mediator-free, microsized yarn biofuel cells are made by simple self-assembly. This system can provide power density up to 236 mW cm−2and an open circuit voltage of 0.61 V. The system maintained 84% of its initial power for 20 days.
Small (Weinheim an der Bergstrasse, Germany), 2016
Boronic acid (BA), known to be a reversible glucose-sensing material, is conjugated to a nanogel ... more Boronic acid (BA), known to be a reversible glucose-sensing material, is conjugated to a nanogel (NG) derived from hyaluronic acid biopolymer and used as a guest material for a carbon multiwalled nanotube (MWNT) yarn. By exploiting the swelling/deswelling of the NG that originates from the internal anionic charge changes resulting from BA binding to glucose, a NG MWNT yarn artificial muscle is obtained that provides reversible torsional actuation that can be used for glucose sensing. This actuator shows a short response time and high sensitivity (in the 5-100 × 10(-3) m range) for monitoring changes in glucose concentration in physiological buffer, without using any additional auxiliary substances or an electrical power source. It may be possible to apply the glucose-sensing MWNT yarn muscles as implantable glucose sensors that automatically release drugs when needed or as an artificial pancreas.
Biomolecule responsive materials have been studied intensively for use in biomedical applications... more Biomolecule responsive materials have been studied intensively for use in biomedical applications as smart systems because of their unique property of responding to specific biomolecules under mild conditions. However, these materials have some challenging drawbacks that limit further practical application, including their speed of response and mechanical properties, because most are based on hydrogels. Here, we present a fast, mechanically robust biscrolled twist-spun carbon nanotube yarn as a torsional artificial muscle through entrapping an enzyme linked to a thermally sensitive hydrogel, poly(N-isopropylacrylamide), utilizing the exothermic catalytic reaction of the enzyme. The induced rotation reached an equilibrated angle in less than 2 min under mild temperature conditions (25-37 °C) while maintaining the mechanical properties originating from the carbon nanotubes. This biothermal sensing of a torsional artificial muscle offers a versatile platform for the recognition of vari...
Torsional behaviors of polymer-infiltrated carbon nanotube (CNT) yarn muscles have been investiga... more Torsional behaviors of polymer-infiltrated carbon nanotube (CNT) yarn muscles have been investigated in relation to molecular architecture by using atomic force microscopy (AFM). Two polymers with different stiffnesses, polystyrene (PS) and poly(styrene-b-isoprene-b-styrene) (SIS), were uniformly infiltrated into CNT yarns for electrothermal torsional actuation. The torsional behaviors of hybrid yarn muscles are completely explained by the volume change of each polymer, based on the height and full width at half maximum profiles from the AFM morphological images. The volume expansion of the PS yarn muscle (1.7 nm of vertical change and 22 nm of horizontal change) is much larger than that of the SIS yarn muscle (0.3 nm and 11 nm change in vertical and horizontal directions) at 80 °C, normalized by their values at 25 °C. We demonstrate that their maximum rotations are consequently 29.7 deg mm(-1) for the PS-infiltrated CNT yarn muscle (relatively larger rotation) and 14.4 deg mm(-1) f...
Improved electrically powered artificial muscles are needed for generating force, moving objects,... more Improved electrically powered artificial muscles are needed for generating force, moving objects, and accomplishing work. Carbon nanotube aerogel sheets are the sole component of new artificial muscles that provide giant elongations and elongation rates of 220% and (3.7 × 10 4 )% per second, respectively, at operating temperatures from 80 to 1900 kelvin. These solid-state–fabricated sheets are enthalpic rubbers having gaslike density and specific strength in one direction higher than those of steel plate. Actuation decreases nanotube aerogel density and can be permanently frozen for such device applications as transparent electrodes. Poisson's ratios reach 15, a factor of 30 higher than for conventional rubbers. These giant Poisson's ratios explain the observed opposite sign of width and length actuation and result in rare properties: negative linear compressibility and stretch densification.
The production of magnesium–chromium oxides by solution combustion synthesis was investigated usi... more The production of magnesium–chromium oxides by solution combustion synthesis was investigated using glycine and urea for the first time. Ammonium dichromate, urea/glycine and ammonium nitrate aqueous solutions were used as the precursors of the oxides. The effect of different reaction parameters, such as fuel richness, stoichiometry and fuel leanness was evaluated; such parameters were modified by changing the reagents and
The synthesis of chromium oxides by solution combustion synthesis was investigated. Ammonium dich... more The synthesis of chromium oxides by solution combustion synthesis was investigated. Ammonium dichromate, glycine, urea and ammonium nitrate dissolved in aqueous solution were used as the precursors of the oxides. The effect of different reaction parameters, such as fuel richness, stoichiometry and fuel leanness was evaluated; such parameters were modified by changing the reagents and the fuel/oxidant ratio. Amorphous CrO3
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Papers by Marcio Lima