Polymer Single-walled Carbon Nanotubes Research Articles

270 MHz passively mode-locked Er-doped fiber laser using single walled carbon nanotube polymer film.

We demonstrated a short-cavity mode-locked erbium-doped fiber laser based on single walled carbon nanotube polymer composite film saturable absorber with a maximum fundamental repetition rate of 270.5 MHz. To the best of our knowledge, this is the highest fundamental repetition rate among mode-locked erbium-doped ring fiber lasers based on nanomaterial polymer composite films. Samples with non-saturable loss range from 13.2% to 60% and modulation depth from 1.63% to 7.08% are prepared by controlling carbon nanotube concentration and film thickness. We systematically investigate the impacts of saturable absorbers on mode-locking repetition rate. Our results show that when the laser repetition rate continuously increases from 15.45 MHz to 270.5 MHz, samples with higher non-saturable loss will push forward the mode-locking threshold and eventually lose mode-locking. In addition, the increased modulation depth will enhance the pulse shaping ability and result in a shorter pulse. Our results may help for high repetition rate mode-locked fiber laser design and improve the laser characteristics. The demonstrated laser may support applications such as frequency comb, etc.

Chronic neural interfacing with cerebral cortex using single-walled carbon nanotube-polymer grids

Objective. The development of electrode arrays able to reliably record brain electrical activity is a critical issue in brain machine interface (BMI) technology. In the present study we undertook a comprehensive physico-chemical, physiological, histological and immunohistochemical characterization of new single-walled carbon nanotubes (SWCNT)-based electrode arrays grafted onto medium-density polyethylene (MD-PE) films. Approach. The long-term electrical stability, flexibility, and biocompatibility of the SWCNT arrays were investigated in vivo in laboratory rats by two-months recording and analysis of subdural electrocorticogram (ECoG). Ex-vivo characterization of a thin flexible and single probe SWCNT/polymer electrode is also provided. Main results. The SWCNT arrays were able to capture high quality and very stable ECoG signals across 8 weeks. The histological and immunohistochemical analyses demonstrated that SWCNT arrays show promising biocompatibility properties and may be used in chronic conditions. The SWCNT-based arrays are flexible and stretchable, providing low electrode-tissue impedance, and, therefore, high compliance with the irregular topography of the cortical surface. Finally, reliable evoked synaptic local field potentials in rat brain slices were recorded using a special SWCNT-polymer-based flexible electrode. Significance. The results demonstrate that the SWCNT arrays grafted in MD-PE are suitable for manufacturing flexible devices for subdural ECoG recording and might represent promising candidates for long-term neural implants for epilepsy monitoring or neuroprosthetic BMI.

Single-wall carbon nanotube promoted allylic homopolymerization for holographic patterning

This article interrogates the mechanism for the incorporation of single-wall carbon nanotubes in the photo-initiated thiol-ene polymerization process and its application in holographic patterning. We find that single-wall carbon nanotube is able to turn on the allylic homopolymerization, which is not involved in the conventional thiol-ene photopolymerization process because of the autoinhibition of allyl monomer. This also leads to an enhancement of conversion for both thiol and allyl monomers. For the first time, the ability of single-wall carbon nanotube that promotes an autoinhibition monomer to homopolymerize is revealed. By applying this new mechanism, a flexible single-wall carbon nanotube-polymer composite film for the use of holographic patterning is demonstrated. The effects of the incorporation of single-wall carbon nanotubes on refractive index modulation and mechanical properties of a volume grating recorded are examined. It is shown that a substantial increase in refractive index modulation and diffraction efficiency is realized by small loading of single-wall carbon nanotubes (0.0015 wt%). This validate the proposed mechanisms provide a simple way to control the photopolymerization and therefore to tailor polymers for optical application uses.

Molecular dynamics simulations of single-walled carbon nanotubes and polynylon66

Polynylon66, as a kind of important engineering plastics, is widely used in various fields. In this work, we studied the interfacial interactions between polynylon66 and single-walled carbon nanotubes (SWCNTs) using molecular dynamics (MD) simulations. The results showed that the polynylon66 could interact with the SWCNTs and the mechanism of interfacial interaction between polynylon66 and SWCNTs was also discussed. Furthermore, the morphology of polynylon66 adsorbed to the surface of SWCNTs was investigated by the radius of gyration. Influence factors such as the initial angle between polynylon66 chain and nanotube axis, SWCNT radius and length of polynylon66 on interfacial adhesion of single-walled carbon nanotube-polymer and the radius of gyration of the polymers were studied. These results will help to better understand the interfacial interaction between polymer and carbon nanotube (CNT) and also guide the fabrication of high performance polymer/carbon nanotube nanocomposites.

Polycarbazole‐Sorted Semiconducting Single‐Walled Carbon Nanotubes for Incorporation into Organic Thin Film Transistors

AbstractThe realization of organic thin film transistors (OTFTs) with performances that support low‐cost and large‐area fabrication remains an important and challenging topic of investigation. The unique electrical properties of single‐walled carbon nanotubes (SWNTs) make them promising building blocks for next generation electronic devices. Significant advances in the enrichment of semiconducting SWNTs, particularly via π‐conjugated polymers for purification and dispersal, have allowed the preparation of high‐performance OTFTs on a small scale. The intimate interaction of the conjugated polymer with both SWNTs and the dielectric necessitates the investigation of a variety of conjugated polymer derivatives for device optimization. Here, the preparation of polymer–SWNT composites containing carbazole moieties, a monomer unit that has remained relatively overlooked for the dispersal of large‐diameter semiconducting SWNTs, is reported. This polymer selectively discriminates semiconducting SWNTs using a facile procedure. OTFTs prepared from these supramolecular complexes are ambipolar, and possess superior mobilities and on/off ratios compared to homo poly(fluorene) dispersions, with hole mobilities from random‐network devices reaching 21 cm2 V−1 s−1. Atomic force microscopy measurements suggest the poly(carbazole)–SWNT composites form more uniform thin films compared to the poly(fluorene) dispersion. Additionally, treating the silicon dioxide dielectric with octyltrichlorosilane is a simple and effective way to reduce operational hysteresis in SWNT OTFTs.

Enhanced dispersion stability of supramolecular complexes of single-walled carbon nanotubes with fluorene-based conjugated polymers

ABSTRACTSupramolecular complexes of single-walled carbon nanotubes (SWNTs) with poly(9,9-didodecylfluorene-2,7-diyl) (PF) derivatives were prepared using a solution dispersion process. A series of novel conjugated PF polymers with carboxyl or hydroxyl end groups at both ends were synthesized by the Yamamoto-type coupling of 2,7-dibromo-9,9-didodecylfluorene using Ni(COD)2 as a catalyst, and further end-capped with either 4-bromobenzoic acid or 4-bromobenzyl alcohol to obtain the end-functionalized PF with different terminal groups. An α-monocarboxy-ω-mono-methoxy poly(ethylene glycol) was connected to both ends of the PF-containing hydroxyl end groups to produce triblock copolymers of poly(ethylene glycol)-b-polyfluorene-b-poly(ethylene glycol) (PEO-b-PF-b-PEO). These SWNTs were completely wrapped with the conjugated polymers through π–π interactions, which enhanced the solubility of the SWNT complexes in organic media, and prevented the aggregation of the polymer–SWNT complexes into large bundles. This indicates that the dispersion stability of SWNTs is enhanced by the addition of the conjugated polymers.

Electrochemical and Electromechanical Properties of Activated Multi-walled Carbon Nanotube Polymer Actuator that Surpass the Performance of a Single-walled Carbon Nanotube Polymer Actuator

The electrochemical and electromechanical properties of actuators fabricated from activated and non-activated multi-walled carbon nanotube (MWCNT)-ionic liquid (IL) gel electrodes are compared with single-walled carbon nanotube (SWCNT)-based actuators. The double-layer capacitance of the MWCNT-COOH electrode was larger than that of the MWCNT electrode but smaller than that of the SWCNT electrode. The activated MWCNT-COOH polymer actuator surpassed the SWCNT actuator in terms of the strain and maximum generated stress.

A nonlocal nonlinear analysis for buckling in embedded FG-SWCNT-reinforced microplates subjected to magnetic field

In this study, nonlocal nonlinear buckling analysis of embedded polymeric temperature-dependent microplates resting on an elastic matrix as orthotropic temperature-dependent elastomeric medium is investigated. The microplate is reinforced by single-walled carbon nanotubes (SWCNTs) in which the equivalent material properties of nanocomposite are estimated based on the rule of mixture. Due to magnetic properties of SWCNTs, the structure is subjected to magnetic field. For the Carbon-nanotube reinforced composite (CNTRC) plate, both cases of Uniform distribution (UD) and Functionally graded (FG) distribution patterns of SWCNT reinforcements are consid- ered. The small size effects of microplate are considered based on Eringen's nonlocal theory. Based on orthotropic Mindlin plate theory along with von Karman geometric nonlinearity and Hamilton's principle, the governing equations are derived. Generalized differential quadrature method (GDQM) is applied for obtaining the buckling load of system. The effects of different parameters such as magnetic field, nonlocal parameters, volume fractions of SWCNTs, distribution type of SWCNTs in polymer, elastomeric medium, aspect ratio and temperature are considered on the nonlinear buckling of the microplate. Results indicate that the buckling load increases with in- creasing magnetic field.

Measurement of the optical properties of a transparent, conductive carbon nanotube film using spectroscopic ellipsometry

We have measured the complex refractive indices of a transparent, conductive carbon nanotube film by spectroscopic ellipsometry at wavelengths of 300–1700 nm (this includes the visible range). The film was produced on a quartz substrate by the doctor-blade method using single-walled carbon nanotube–polymer ink. The imaginary part of the complex refractive index of the film was found to be lower than 0.09 over the entire wavelength range. This film has a large advantage as a transparent, flexible, and conductive material.

Temperature-dependent nonlocal nonlinear buckling analysis of functionally graded SWCNT-reinforced microplates embedded in an orthotropic elastomeric medium

In this study, nonlocal nonlinear buckling analysis of embedded polymeric temperature-dependent microplates resting on an elastic matrix as orthotropic temperature-dependent elastomeric medium is investigated. The microplate is reinforced by single-walled carbon nanotubes (SWCNTs) in which the equivalent material properties nanocomposite are estimated based on the rule of mixture. For the carbon-nanotube reinforced composite (CNTRC) plate, both cases of uniform distribution (UD) and functionally graded (FG) distribution patterns of SWCNT reinforcements are considered. The small size effects of microplate are considered based on Eringen's nonlocal theory. Based on orthotropic Mindlin plate theory along with von K<TEX>$\acute{a}$</TEX>rm<TEX>$\acute{a}$</TEX>n geometric nonlinearity and Hamilton's principle, the governing equations are derived. Generalized differential quadrature method (GDQM) is applied for obtaining the buckling load of system. The effects of different parameters such as nonlocal parameters, volume fractions of SWCNTs, distribution type of SWCNTs in polymer, elastomeric medium, aspect ratio, boundary condition, orientation of foundation orthtotropy direction and temperature are considered on the nonlinear buckling of the microplate. Results indicate that CNT distribution close to top and bottom are more efficient than those distributed nearby the mid-plane for increasing the buckling load.

PFO–BPy solubilizers for SWNTs: Modelling of polymers from oligomers

Due to their exeptional physical properties, single walled carbon nanotubes (SWNTs) embedded in organic polymers (polymer–SWNT hybrid systems) are promising materials for organic photovoltaic devices. Already at the SWNT sorting and debundling step, polymers such as the copolymer of 9,9‐dioctylfluorenyl‐2,7‐diyl and bipyridine (PFO–BPy) are used as solubilizers. However, to model polymer–SWNT hybrid systems, we must first determine the smallest oligomer needed to sufficiently describe the electronic and optical absorption properties of the polymer. To do so, we use time dependent density functional theory (TDDFT) to model the PFO–BPy polymer using the monomers, dimers and trimers of the PFO–BPy and Py–PFO–Py building blocks, which are also compared to the infinitely long polymer. We find the Py–PFO–Py monomer, with shortened side chains, already describes the PFO–BPy polymer within the expected accuracies of TDDFT.

Humidity dependent electrical response of bilayer device based on poly (3,4-ethylene dioxythiophene)-poly (styrene sulphonate) and single walled carbon nanotubes

We report the electrical properties of polymer nanocomposite bilayer device based on conducting polymer poly (3,4-ethylene dioxythiophene)-poly (styrene sulphonate) and single walled carbon nanotubes. The resistivity of the low conductivity grade polymer poly (3,4-ethylene dioxythiophene)-poly (styrene sulphonate) decreases with increase in humidity, while single walled carbon nanotube polymer nano-composite exhibits a reverse trend as compared to pure polymer. A voltage upto 500mV is generated across the bilayer device made of pure polymer and its nano-composite. The voltage changes instantaneously with the change in humidity. The generated voltage has been found to increase with increase in humidity.

Electrochemical and electromechanical properties of carbon black/carbon fiber composite polymer actuator with higher performance than single-walled carbon nanotube polymer actuator

The electrochemical and electromechanical properties of poly(vinylidene fluoride-co-hexafluoropropylene) based actuators using carbon black (CB)/vapor grown carbon fiber (VGCF)/ionic liquid (IL) composite gel electrodes formed without ultrasonication were compared with those of actuators using only CB or VGCF. The double-layer capacitance of the CB/VGCF/IL electrodes was larger than that of the CB/IL electrodes and increased with VGCF content. The amount of strain exhibited by the CB/VGCF/IL actuators was also larger than that for the CB/IL actuators, with the highest strain being produced for an actuator with a CB:VGCF ratio of 1:1. This was slightly larger than that for a polymer actuator using single-walled carbon nanotubes (SWCNTs), indicating that the proposed actuators exhibit sufficiently high performance for real-world applications without the need for expensive SWCNTs. Furthermore, the frequency dependence of the displacement response of the CB/VGCF/IL polymer actuators was successfully simulated using an electrochemical kinetic model similar to that for SWCNT-based actuators. The results yielded the strain in the low-frequency limit and the time constant of the response.

A Passively Mode-Locked Erbium-Doped Fiber Laser Based on a Single-Wall Carbon Nanotube Polymer

We demonstrate a simple, compact and low-cost mode-locked erbium-doped fiber laser (EDFL) using a single-wall carbon nanotube (SWCNT) poly-ethylene oxide (PEO) composite as a passive saturable absorber (SA). The composite with an SWCNT concentration of 18wt% is prepared by mixing the SWCNT homogeneous solution with a diluted PEO polymer solution. A droplet of the polymer composite is applied on the fiber ferrule end, which is then mated to another clean ferrule connector to construct an SA. The SA is then integrated into the laser system to self-start stable mode locking at 1557 nm without employing a polarization controller. The EDFL generates a stable soliton pulse train with a duration of 0.81 ps, repetition rate of 44 MHz and average output power of 92.4 μW at a 980 nm pump power of 26.8 mW. The soliton laser starts to lase at a pump power threshold of 14.6 mW.

Transparent Stretchable Single‐Walled Carbon Nanotube‐Polymer Composite Films with Near‐Infrared Fluorescence

We report transparent stretchable single-walled carbon nanotube-polymer composite films that emit pronounced Raman and near-infrared fluorescence with a fine spatial resolution. The independent modulation in Raman and fluorescence spectra is demonstrated in response to touch and temperature. The optical signal transduction of transparent stretchable optoelectronic films may enable a paradigm shift in touch-sensing devices eliminating electrical interconnects.

Effects of Purity on the Mechanical Properties of Single-Walled Carbon Nanotubes-Polymer Nanocomposites

Effects of Purity on the Mechanical Properties of Single-Walled Carbon Nanotubes-Polymer Nanocomposites

Conformationally switchable TTFV–phenylacetylene polymers: synthesis, properties, and supramolecular interactions with single-walled carbon nanotubes

A series of π-conjugated polymers made up of tetrathiafulvalene vinylogue (TTFV) and phenylacetylene repeat units was synthesized and investigated as supramolecular hosts for non-covalent functionalization of single-walled carbon nanotubes (SWNTs). Adopting a folding conformation in the neutral state, these polymers can effectively interact with individual SWNTs forming supramolecular complexes with good solubility in organic solvents. Responding to certain external chemical stimuli (e.g., oxidation or protonation), however, the polymers change their molecular shapes into a linear structure driven by the formation of TTFV cations and hence result in reversible dissociation of the polymers from SWNTs. Such a process allows the efficient releasing of pristine SWNTs from polymer dispersants. The detailed polymer–SWNT interactions and relevant selectivity for certain types of SWNTs were examined by various spectroscopic analyses. Intriguing bulk materials, such as “bucky gels” and conductive “bucky films”, were obtained from the polymer–SWNT composites and their structural and physical properties were characterized as well.

A mesoporous carbon polymer actuator with superior performance to that of single-walled carbon nanotube polymer actuators

The electrochemical and electromechanical properties of poly(vinylidene fluoride-co-hexafluoropropylene) actuators prepared using a nongraphitized mesoporous carbon black (MCB)–ionic liquid (IL) gel electrode formed without ultrasonication were compared with those of actuators prepared using carbon black (CB), multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). The double-layer capacitances for the MCB/IL electrodes were larger than that for the CB/IL electrode. In particular, the double-layer capacitance for the MCB/EMI[BF4] electrode was larger than that for other MCB-based electrodes. Over a wide frequency range of 0.005–1.0 Hz, the strain produced by the MCB/EMI[BF4] actuator was larger than that of the other MCB-based actuators. This suggests that there is a relationship between the pore size in the MCB and the IL anion size. The maximum strain value for the MCB/EMI[BF4] actuator was larger than that for the non-MCB-based actuators, and in particular, was about 1.5 times larger than that for the SWCNT-based actuators. Thus, an MCB-based actuator formed without ultrasonication exhibited a performance that surpassed those of the CB- and SWCNT-based actuators. Consequently, it could generate sufficient strain for real-world applications without the need for specialized SWCNTs.

Controllable fabrication and electromechanical characterization of electrophoresis assembled single-walled carbon nanotube-polymer film transducers

This paper presents a controllable electrophoresis allowing a directed deposition of negatively charged single-walled carbon nanotubes (SWNTs) on an electro-active polymer to fabricate thin-film transducers under an electric field excitation. The assembled high-density SWNT networks are verified with SEM micrograph and Raman spectroscopy, and the electric filed-induced mechanism for electrophoresis of SWNT is investigated using electrochemical analysis technique. The dynamic electromechanical properties are characterized by a combinative approach of piezoelectric excitation and laser vibrometer measurement. A remarkable performance enhancement and tunability for such thin-film transducers in both resonant frequency and quality factor is demonstrated, compared with pure polymer. This observed enhancement can not only be exploited to tailor the thin-film transducers for desired electromechanical properties, but also create versatile pathways for variety of applications including polymeric electronic technologies.

Comparison of electrochemical and electromechanical properties of a high performance carbon black polymer actuator and a single-walled carbon nanotube polymer actuator

The electrochemical and electromechanical properties of actuators prepared using a carbon black (CB)-ionic liquid (IL) gel electrode containing manganese oxide (MnO2) and formed without ultrasonication were compared with actuators prepared using only-CB, only-multi-walled carbon nanotubes (MWCNTs), only-activated multi-walled carbon nanotubes (MWCNT-COOH) and only-single-walled carbon nanotubes (SWCNTs). The CB polymer actuator containing MnO2, prepared without ultrasonication, surpassed the strain performance of the only-CB, only-MWCNT, only-MWCNT-COOH and only-SWCNT actuators. The capacitance of the MnO2/CB/IL electrode contributes to the pseudocapacitance, and for low frequencies, the strain for the MnO2/CB/IL actuator is the dominant contributor to the pseudocapacitance. Therefore, it is considered that the mechanism for MnO2/CB/IL actuation is different from that for the only-SWCNT and only-MWCNT-COOH actuators. Both CB and MnO2 are required to produce a large strain actuator that surpasses the performance of the SWCNT polymer actuator and has characteristics sufficient for practical applications (e.g., in tactile displays).