C60 Content Research Articles

A novel fluorescence sensing strategy for identification and quantitation of C60 and C70 by multi-emission lanthanide-disalicylaldehyde hybrid

Till now, there is still a lack of the convenient and efficient approach to implement identification and quantitation of fullerenes in various domains. This work provides the first example for detecting fullerenes by an adequate fluorescent probe, in parallel with the new methodology for detecting fullerenes by the fluorescent chemosensing approach. Using a multi-emission lanthanide-disalicylaldehyde coordination hybrid H2Qj2/Tb0.91Eu0.09, the rapid, selective and discriminative detection of analogous C60 and C70 can be easily achieved after the spectral and statistical analyses of fluorescent sensing signals on four emission bands (416, 543, 447 and 615 nm), excited by two irradiation lights (370 and 394 nm). Titration experiments further verify the very high linearity for both C60 and C70 and allow their detection at concentrations as low as 1.72 μM (C60) and 0.09 μM (C70). Moreover, this fluorescent probe also shows its reliable abilities to identify proportional C60/C70 mixtures and monitor C60 and C70 contents in actual soil sample. It is believed that our proposed lanthanide-base fluorescent matrix not only verify the feasibility and potential of fluorescent chemosensing methodology for the fullerene detection but also provide a valuable tool for potential applications.

Revealing patterns of change in the tribological efficiency of composite materials for machine parts based on phenylone and polyamide reinforced with arimide-t and fullerene

The object of the study is the process of changing tribological efficiency according to tribotechnical characteristics (wear intensity, friction coefficient, temperature in the contact zone) of composites based on phenylone C-1 and polyamide PA-6 with arimide-T filler and fullerene C-60. The study solved the problem of obtaining composites with high wear resistance. Based on the results of research, it was found that varying the content of arimide-T makes it possible to obtain composites with different patterns of changes in tribotechnical characteristics under conditions of dry friction, lubrication with water and I-50 oil. Composites with the composition: phenylone C-1+15 wt. have the maximum tribological efficiency. % arimide-T+3 wt. % fullerene C-60 and polyamide PA-6+30 wt. % arimide-T+3 wt. % fullerene C-60. Phenylone C-1 has destructive properties when working in the environment of water and temperature in the friction zone. Its reinforcement with arimide-T and fullerene C60 gave positive results of a complex of tribotechnical characteristics under these conditions. It was found that the wear of composites based on phenylone C-1 in I-50 oil is two orders of magnitude lower than in water. Research of samples from the obtained composites based on phenylone C-1 and polyamide PA-6, reinforced with the optimal content of arimide-T and fullerene C60, showed that their wear resistance when lubricated with oil is 3.5...4.0 times greater than the wear resistance of bronze. An applied aspect of the reported results is the introduction of manufacturing technologies and restoration of machine parts from the proposed composites. It has been proven that their optimal composition contributes to high tribological efficiency and could provide the required level of wear resistance and reliability of resource-determining nodes, systems, and machine assemblies. The results could be used by machine-building and repair-technological enterprises

Optical, electrical, and structural properties of polyethylene oxide/fullerene nanocomposite films

Polyethylene oxide (PEO)/fullerene (C60) nanocomposite films were synthesized through a solution mixing and casting method. The influence of increasing C60 concentration on thermal stability is evident in thermogravimetric analysis (TGA) profiles. TGA is employed to assess the thermal stability of polyethylene oxide (PEO) films, revealing a gradual weight loss below 200°C and pronounced degradation between 200°C and 500°C. PEO films doped with C60 improve their stability, with the 8 wt% C60 film retaining 40 wt% of its initial weight at 425°C—four times greater than the 1 wt% C60 film. XRD patterns exhibit a progressive reduction in crystallinity, decreasing from 52% to 38% with higher C60 content. Furthermore, C60 introduction leads to a reduced transmittance in the visible region, a redshift in the band edge, indicative of decreasing bandgap energy from 3.95 eV to 3.59 eV. Overlapping absorption bands in the extinction coefficient spectra (490 nm–620 nm) corresponded to π-π* and n-π* transition bands of C60. The electrical conductivity of PEO/C60 nanocomposite films demonstrate a substantial increase directly proportional to C60 concentration, reaching approximately 200-fold the conductivity of undoped PEO (2.28 × 10−6) at 8 wt% (1.11 × 10−4 S cm−1).

Comparative analysis of dynamic mechanical properties of steel fiber reinforced concrete under ambient temperature and after exposure to high temperatures

The dynamic properties of concrete structures after being exposed to high temperatures play a crucial role in post-disaster repair and accident prevention measures. This study examined three different mixture ratios of Steel Fiber Reinforced Concrete (SFRC) with matrix strength of C60 and steel fiber contents of 0%, 1%, and 2%. A Split Hopkinson Pressure Bar (SHPB) with a diameter of 75 mm, along with a heating furnace, was employed to comprehensively investigate the dynamic compression behavior of materials. The specimens were exposed to temperatures ranging from 200 °C to 600 °C. In addition to evaluating the extent of mechanical degradation in SFRC after cooling, auxiliary impact experiments were also carried out at ambient temperature. The experimental data revealed that the dynamic peak stress and peak strain initially increased but eventually decreased as the loading rates continued to rise. The degree of strengthening, toughening, and energy absorption capacity of concrete materials progressively decreased as the escalation of strain rate after the cooling process. Moreover, the inclusion of steel fibers proved effective in preventing cracking and damage to the concrete, preserving the integrity of specimens even at higher temperatures. Simultaneously, the residual stress and deformation capacity of SFRC showed considerable enhancement after exposure to elevated temperatures.

Highly aqueously stable C60-polymer nanoparticles with excellent photodynamic property for potential cancer treatment.

Fullerenes are a class of carbon nanomaterials that find a wide range of applications in biomedical fields, especially for photodynamic cancer therapy because of its photosensitive effect. However, hydrophobic fullerenes can only be dispersed in organic solvents which hinders their biomedical applications. Here, we report a facile method to prepare highly water-dispersible fullerene (C60)-polymer nanoparticles with hydrodynamic sizes of 50-70nm. Hydrophilic random copolymers containing different ratios of polyethylene glycol methyl ether methacrylate and 2-aminoethylmethacrylamide were synthesized for conjugating with C60 molecules through efficient nucleophilic Michael addition reaction between amine groups from hydrophilic polymer and carbon-carbon double bonds from C60. As a result, the amphiphilic C60-polymer conjugates could be well dispersed and nano-assembled in water with a C60 concentration as high as 7.8mg/mL, demonstrating a significant improvement for the solubility of C60 in an aqueous system. Owing to the high C60 content, the C60-polymer nanoparticles showed a strong photodynamic therapy effect on human lung cancer cells (A549) under light irradiation (450nm) in both 2D cell culture and 3D spheroid culture, while demonstrating ignorable cytotoxicity under dark. This highly efficient and convenient method to prepare water-dispersible C60-polymer conjugates may have a great impact on the future biomedical applications of fullerenes.

Poly(ethylene glycol)–Fullerene Composite Films and Free-Standing Nanosheets for Flexible Electronic Devices and Sensors

A series of ultrathin (80–100 nm) poly(ethylene glycol)–fullerene (PEG-C60) composite films were fabricated by three different methods, denoted immersion, one-pot, and reflux. These films are composed of cross-linked amine-/epoxy-decorated STAR-PEGs and disk-shaped C60 clusters with an average diameter of 314–329 nm and narrow size distribution. The clusters are located either on the surface of the films (immersion) or embedded in their bulk, coupling either physically (one-pot) or chemically (reflux) to the PEG network. The content of C60 in the composite films varies depending on the preparation method and is highest (∼30%) in the case of reflux, featuring also a shift of the lowest unoccupied molecular orbital energy of C60 by ∼70 meV compared to the immersion case. These films exhibit distinct optical and electrochemical properties of C60, merged with some favorable characteristics of the PEG matrix and resulting, in particular, in good electrochemical conductivity and high elasticity. The films can be separated from the substrate, forming composite nanosheets, which can be either used as free-standing ones or transferred to a secondary substrate with the preservation of the original properties. Potential applications of PEG-C60 films and nanosheets include flexible electronic devices, photodetectors, and electrochemical sensors, including biosensors in particular.

Effect of fullerene C60 admixture in paraffin wax on the refractive index and phase transition temperatures

The paraffin wax (PW) utilized as a phase change material is promising for thermal energy storage systems. However, the application of this material is limited by itslow thermal conductivity. The fullerene C60 adding in PW can help to eliminate this problem.Therefore, the system PW/C60 is promising for studying its properties.
 The results of an experimental study of the refractive index of solutions of fullerene C60 in PW of 52...54 °C melting point at the ranges of С60content of 0...0.052 wt. %and temperatures of 41…65 °С are presented in the study. The complex character of the concentration dependence of the refractive index on isotherms for the studied thermodynamic systems has been registeredboth in liquid and solid phases.Data on the effect of the C60 content in PW on the temperatures of the start and finish of its phase transition is presented. At C60 content in PW of 0…0.01 wt. % the temperatures of the start and finish of the phase transition decreased, at C60 content of 0.01…0.04 wt. % they increased more than the pure PW temperatures and at C60 content more than 0.04 wt. % they decreased again.
 The obtained effects of a decrease and increase in the refractive index on the isotherms and temperatures of start and finish of PWcrystallizationcan be explained by structural transformations in PW caused by C60 presence. In the authors' opinion, the reason for the extreme behavior of concentration dependence of the refractive index of objects of study is the effect of C60 on the density fluctuations and the quasi-crystalline structure of the liquid and solid phases.These structural transformations in PW cause a similar change inthe concentration dependencies of the temperatures of the start and finish of the phase transition of objects of study.

Novel [60]fullerene polymers: Part 2: Synthesis and polymerisation processes through acrylation of N-(4-hydroxyphenyl)-o-hydroxy-2-phenyl fulleropyrrolidine derivatives and their monomers

Following on from part 1 of this paper where linear C60 polymers were synthesised, part 2 describes the synthesis of crosslinked and branched chain C60 polymers so that the amount of C60 content in the polymer, the number averaged molecular weight “Mn” and the weight averaged molecular weight “Mw” may be increased. This paper reviews the method in which fulleropyrrolidines were prepared by [3 + 2] cycloaddition of azomethine ylides to [60]fullerene cage through the use of N-(4-hydroxyphenyl) glycine in conjunction with benzaldehyde derivatives. Numerous types of [60]fullerene polymers were synthesised through fulleropyrrolidine acrylic monomers. In this study, the cycloaddition process was selected because it provides a powerful tool for fullerene functionalisation, as a result very stable cycloadducts are formed. The addition of azomethine ylide was found to provide a versatile method for the derivatization of [60]fullerene. In this case, the synthesis of functionalised C60 and novel branched chain and crosslinked network of fullerene polymers has been investigated. The first step in this study was to prepare dihydroxy fulleropyrrolidines by [3 + 2] cycloaddition of azomethine ylide to [60]fullerene. The fulleropyrrolidine monomer having multiple functional groups was put up by the reaction of –OH groups of fulleropyrrolidine with acryloyl chloride in the presence of a base in an alcoholic solution. FT-IR, Mass spectra,1H NMR and UV techniques were used to characterise the reaction products obtained. Benzoyl Peroxide was used as a free radical initiator to polymerise the monomer in dimethylformamide. DMF is a highly suitable solvent for this procedure because both C60 monomer and polymer are soluble. In this work, the process parameters such as time of reaction, reaction temperature, mole ratio, type of solvent, and quantity of reagents used were varied in so as to obtain the highest yields of fulleropyrrolidines, monomers and polymers.

Stable colloidal dispersions of fullerene C60, curcumin and C60-curcumin in water as potential antioxidants

Despite many advantages, the practical application of fullerene C60 and curcumin (CUR) has been limited by their hydrophobic nature, deficient solubility in aqueous media and, therefore, poor bioavailability. In this study, aqueous nanoformulations containing C60 and CUR in the absence and presence of three solubility enhancers, β-cyclodextrin (CD), Tween 80 (T80) and polyvinylpyrrolidone (PVP), were prepared and subjected to the antioxidant activity assessment. The content of C60 and CUR, stability, size and morphology of nanoparticles were determined using UV–vis, DLS and SEM techniques. Contrary to better solubility of pure C60 than the corresponding C60-CUR system, the solubilization of CUR in hybrid suspensions was improved compared to corresponding pure CUR suspensions, with the exception of the C60-CUR-PVP formulation. The DLS results revealed nearly monodisperse nature of CUR-T80 nanoformulation, while other ones ranged from widely dispersed to polydispersed. Depending on the type of solubilizer, similarity was observed in the particle size distributions of T80- and PVP-coated nanoformulations as well as water and CD nanoformulations. The presence of T80 differently and significantly reduces the particle size in all three nanoformulations, while PVP slightly reduces CUR-based nanoparticles but increases the size of C60 nanoparticles. Zeta potential values, ranging from − 9 mV to − 34 mV, show variation in the starting stability of nanoparticles, from unstable or relatively stable three PVP formulations and C60-T80 to highly stable CUR-T80 and C60-water. Compared to water nanoformulations as a control, SEM images of dispersant-coated nanoparticles lost the visible morphology of active components, showing variation in their morphology depending on the type of dispersant and active component used. Nanoformulations containing CUR in PVP and T80 expressed a very good antioxidant potential in DPPH radical scavenging assay, much stronger than ascorbic acid. At the same time, a moderate to high antioxidant activity in β-carotene bleaching assay was reached in PVP and T80 nanoformulations containing C60, CUR, and their noncovalent hybrid, as well. Our studies have shown that T80 and PVP colloidal systems containing C60-CUR hybrid, but also their individual components, can be used as stable antioxidant nanoformulations with potential application in the field of food and pharmacology.

Study of Optical, Thermal, Mechanical and Microstructural Properties of Fullerene/Poly (vinylidene fluoride) Polymer Nanocomposites

Fullerene (C60)/ poly (vinylidene fluoride) PVDF polymer nanocomposites (PNCs) films were prepared using a solution casting route. The optical, microstructural, thermal, and mechanical properties of pure PVDF and C60-PVDF polymer nanocomposite films were studied using UV-Visible & Fourier Transform infrared (FTIR) spectrophotometer, X-ray diffractometer, Thermo-gravimetric analyzer, Tensile tester, and Field emission scanning electron microscope. An absorption band near 350 nm in the absorption spectrum shows the presence of C60 nanoparticles in the PNC film. In the FTIR spectrum, the presence of vibrational bands near 510 and 840 cm-1 suggest the development of β-phase of PVDF in PNC films. An increase in the degradation temperature from 444 0C in pure PVDF to 506 0C in PNC with 0.5 wt% C60 is ascribed to cross-linking occurring between C60 and polymer in PNC films. Both thermal conductivity and Young’s modulus vary non-linearly with C60 content in PNC films. Microscopic image shows agglomerated C60 particles of diameter ~550 nm, which were cross-linked to PVDF particles.

Electrically responsive materials based on dibutyl phathalate plasticized poly(lactic acid) and spherical fullerene

Carbon-based electromechanical actuators, capable of reversible shape changes in response to electrical stimuli, have found many potential utilizations such as robotic artificial muscles, micro-pumps, and sensitive switches. In this work, electroactive materials based on the dibutyl phathalate (DBP) plasticized poly(lactic acid) (PLA) and fullerene (C60) were produced by a simple solvent casting method. The PLA composites exhibited fast and reversible responses under electrical stimulus. The highest storage modulus response was obtained from the 1.0%v/v C60/PLA/DBP at 23.51 × 105 Pa under the 1.5 kV mm−1 electric field. In the bending experiment, the PLA composites bended towards the anode from the attractive force between the negative charges of the induced dipole moments namely the carbonyl groups in PLA and DBP and the π-conjugated electrons of C60 and the positive electrode. The C60/PLA/DBP composite with a small C60 content (0.1%v/v) yielded the maximum bending distance of about 6.0 mm within 10 s and the highest dielectrophoresis force of 1.01 mN at 550 V mm−1. Thus, the electrically responsive PLA composites fabricated here with the short response time and high bending deformation are demonstrated here to be promising biobased materials towards actuator applications.

Electronegative polyvinylidene fluoride/C60 composite nanofibers for performance enhancement of triboelectric nanogenerators

Recently, sustainable energy harvesting technologies have received much attention for powering the internet of things architecture. Triboelectric nanogenerators (TENGs) have been regarded as the most promising energy harvesting technology because they can generate a large amount of electrical energy even with very weak mechanical energy and very simple structures. Although there has been much investigation, TENG devices continue to be associated with insufficient levels of converted electrical power. In this study, we report the enhancement of TENG performance outputs based on polyvinylidene fluoride (PVDF)/fullerene (C60) composite nanofibers (NFs). Structural and chemical investigations show that C60 is uniformly incorporated into PVDF NFs with C60 content levels of less than 0.3 mg. PVDF/C60 composite NFs exhibit a consistent β-phase ratio regardless of the C60 content. Here, as the C60 content was increased from 0 to 0.2 mg, the maximum output power of the PVDF/C60 composite NF-based TENG devices increased from 129 to 282 μW, while it decreased to 147 μW with further addition of C60 beyond 0.4 mg. The enhanced TENG performance realized with an increase in the C60 content originated from the increased trap charge ability and the high electronegativity caused by the incorporated C60 in the PVDF matrix. The output power from a PVDF/C60 composite NF-based TENG device was sufficient to operate an eco-friendly display device.

Non-Einstein Rheology in Segmented Polyurethane Nanocomposites

To provide a fundamental understanding regarding the potential of nanoparticle-induced viscosity reduction in segmented block copolymer-based nanocomposites, the shear rheological behavior of segmented polyurethane/C₆₀ nanocomposites (NPUs) was studied up to 2 wt % C₆₀, and the results were complemented by several dynamic and structural probes. The same microstructural features and dynamical relaxations were revealed for each matrix (PU) and its corresponding NPUs in the absence of deformation, representing the lack of difference in their dynamical behaviors at all studied C₆₀ content. Under shear, however, interesting changes in the terminal rheological properties of PUs were observed in the presence of a C₆₀ nanofiller. An anomalous terminal shear viscosity (η₀) reduction was found for microphase-mixed PUs at a low C₆₀ content of up to 0.5 wt %. However, the microphase-mixed NPUs containing a higher C₆₀ content as well as the microphase-separated NPUs showed a higher η₀ than their matrices. Slippage at the polymer/C₆₀ interfaces was suggested as a possible mechanism behind the viscosity reduction, which appeared controllable by the degree of microphase separation, the ratio of slip length to the nanoparticle size, and the stiffness of segments. Accordingly, an effective slip length, bₑff, was considered as the key factor in controlling the observed noncontinuum effects regarding the nanoparticle-induced viscosity reduction in the microphase-mixed PUs. When most C₆₀ nanoparticles of radius r are positioned on the hard segments (HSs) of microphase-mixed PUs, bₑff/r > 1 can lead to viscosity reduction, while the localization of C₆₀ in the vicinity of soft segments (SSs) increased the matrix’s η₀. A semiuniversal curve was also found to roughly estimate the η₀ values of various NPUs.

Microwave absorption properties of polyaniline (PAni) with various amount of carbonaceous material (CM)

This study investigates the microwave absorption properties of polyaniline (PAni) with varying carbonaceous material, CM (Fullerene,C60) contents. PAni nanocomposites were prepared with varying contents of C60 ranging from 5 to 40% through a chemical oxidation method by using carboxylic acid as the dopant. The functional groups of PAni nanocomposites were validated by Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet–visible (UV–Vis) Spectroscopy analyses. The surface morphology of nanocomposites and the presence of titanium dioxide (TiO2) and C60 were confirmed by Field Emission Scanning Electron Microscopy (FESEM) and X-ray Diffractometry (XRD), respectively. Microwave absorption studies were carried out using Microwave Vector Network Analyzer (MVNA) from 0.5 to 18.0 GHz. The study showed that PAni nanocomposites with 10% of C60 formed the nanorods/nanotubes with the biggest diameter of 200 nm as compared to other PAni nanocomposites. It was found that PAni nanocomposites with 10% C60 also recorded the highest electrical conductivity and relative permittivity of 1.708 × 10–1 S/cm and 9.97, respectively. The nanocomposite that was formulated with 10% of C60 showed an improvement of interchain and intrachain charge transfer as well as molecular polarization along the PAni backbone. Hence, it eventually reduces the electrical energy dissipated by PAni, and finally enhances the microwave absorption properties with the highest reflection loss (RL) of −61.3 dB at 9 GHz.

Photoresponsive Thermoelectric Materials Derived from Fullerene-C60 PEDOT Hybrid Polymers

A series of fullerene-C60-PEDOT hybrid polymers HP1–7 with different contents of C60 were successfully prepared and characterized in terms of UV–vis absorption spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Poly­(3,4-ethylenedioxythiophene) (PEDOT) chains were grafted onto the surface of C60, where C60 was covalently dispersed into the whole hybrid polymer network. The thermoelectric (TE) properties of hybrid polymer films were investigated in the dark condition and under visible light irradiation. In the dark condition, the HP1 (0.00 wt % C60) films showed an electrical conductivity (σ) of 240 ± 5 S cm–1 and a Seebeck coefficient (S) of 10 ± 0.6 μV K–1. By increasing the C60 content in hybrid polymers, the σ gradually decreased to 70 ± 10 S cm–1 (HP7, 5.00 wt % C60). In contrast, the S rapidly increased to 19 ± 0.5 μV K–1 (HP4, 1.00 wt % C60) and then reached 22 ± 1.0 μV K–1 for HP7. A maximum power factor (PF) of 5.8 ± 0.2 μW m–1 K–2 was achieved for HP3 films with 0.50 wt % C60. Under light irradiation, the S of HP2–4 were decreased from 13 ± 0.8, 17 ± 0.9, and 19 ± 0.5 to 9 ± 0.4, 8 ± 0.6, and 12 ± 0.4 μV K–1, respectively, leading to decreased PFs of 1.9 ± 0.2, 1.5 ± 0.1, and 2.4 ± 0.2 μW m–1 K–2, respectively. HP3 exhibited the highest light-inhibited efficiency of the TE property with its PF of approximately one-fourth of that obtained under visible light irradiation, revealing that the TE performance of these fullerene-C60-PEDOT hybrid polymers could be feasibly controlled by the irradiation of the visible light.

Thermodynamic and structural properties of polystyrene/C60 composites: A molecular dynamics study**Project supported by the National Key Research and Development Program of China (Grant No. 2016YFA0200902), Science and Technology Commission of Shanghai Municipality, China (Grant No. 17JC1400801), and Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 51705369).

To tailor properties of polymer composites are very important for their applications. Very small concentrations of nanoparticles can significantly alter their physical characteristics. In this work, molecular dynamics simulations are performed to study the thermodynamic and structural properties of polystyrene/C60 (PS/C60) composites. The calculated densities, glass transition temperatures, and coefficient of thermal expansion of the bulk PS are in agreement with the experimental data available, implying that our calculations are reasonable. We find that the glass transition temperature Tg increases accordingly with an added concentration of C60 for PS/C60 composites. However, the self-diffusion coefficient D decreases with increase of addition of C60. For the volumetric coefficients of thermal expansion (CTE) of bulk PS and PS/C60 composites, it can be seen that the CTE increases with increasing content of C60 above Tg (rubbery region). However, the CTE decreases with increasing content of C60 below Tg (glassy region).

C60 fullerene loaded hydroxyapatite-chitosan beads as a promising system for prolonged drug release

Bioactive composite material in the form of beads, based on natural polysaccharide Chitosan (CS), hydroxyapatite (HA), and C60 fullerene (C60), was synthesized under influence of microwave irradiation (MW). The bead is a 3D matrix consisting of CS macromolecules cross-linked with sodium tripolyphosphate with HA and C60 particles immobilized in its structure. XRD and FTIR data confirmed the formation of calcium deficient carbonate substituted HA with needle-shaped nanocrystallites of about 80 nm. MW does not influence CS structure. C60 enhances the beads shape stability. HPLC studies suggest the (up to 18 days) prolonged release of hydrophobic Anaesthesinum from C60-containing composites. Changing the C60 content allows adjusting the drug release time. The presence of CS and C60 provides the Anaestesinum release profile, according to the calculated correlation coefficient (r = 0.99), close to the zero order kinetic release profile. The inhibition zone test (ZOI) shows the antimicrobial activity of the composites containing 0.004 mg/ml C60 against S. aureus ATCC 25923 and E. coli ATCC 25922 (ZOI 16 ± 1 and 10 ± 2 mm, respectively). Cell viability test indicates no toxicity of 0.3 and 0.15 mg/ml C60-containing composites.

Evolution of dispersion in the melt compounding of a model polymer nanocomposite system: A multi-scale study

We investigate the morphological development of polystyrene (PS)-C60 nanocomposites along the length of a prototype co-rotating twin-screw extruder with sampling capabilities. The effects of C60 concentration and output on the morphological evolution along the extruder are studied employing a suite of characterization techniques covering a wide range of length-scales, thereby shedding new light on the dispersion mechanism in this model system. We show that the relatively new spin-echo small-angle neutron scattering (SESANS) technique is well suited to probe both the distribution and the dispersion of C60. SESANS complements optical microscopy (OM) data as it covers sampling areas several orders of magnitude larger than OM. The multi-scale morphological information conveyed by OM, SESANS, SANS and rheological data shows that for larger outputs, C60 agglomerates are eroded as they travel along the extruder, resulting in C60 dispersion and distribution at both molecular and micrometric levels. The picture is more complex when smaller feed rates are used, as the evolution of C60 dispersion depends on the C60 loading. For larger C60 contents, agglomeration develops along the extruder, whereas dispersion is improved for smaller C60 contents. Overall, it is concluded that an over-high feed rate in extrusion does not necessarily result in a bigger size of the nanoparticle agglomerates because of the complex interplay between stresses and residence time.

Facile method to fabricate poly(L-lactic acid)/C60 tetragonal single crystal composites with enhanced thermal stability

For the first time, the poly(L-lactide acid) (PLLA) composites with C60 tetragonal single crystal (C60TSC) were fabricated through facile evaporation of the CHCl3 solution containing PLLA and C60. Results showed C60TSC in composites had side length in micron scale, and their mean size decreased, their number increased with C60 content in composites. The C60TSC in composites were face-centered cubic (fcc) lattice C60 single crystal composed of monomeric C60, and displayed blueshift relative to the UV absorption bands of C60. C60TSC formation resulted in PLLA composite with higher thermal stability, higher cold crystallization temperature as well as higher melting temperature than neat PLLA.

Striking Effect of Polymer End-Group on C60 Nanoparticle Formation by High Shear Vibrational Milling with Alkyne-Functionalized Poly(2-oxazoline)s.

Buckminsterfullerene (C60) has a large potential for biomedical applications. However, the main challenge for the realization of its biomedical application potential is to overcome its extremely low water solubility. One approach is the coformulation with biocompatible water-soluble polymers, such as poly(2-oxazoline)s (PAOx), to form water-soluble C60 nanoparticles (NPs). However, uniform and defined NPs have only been obtained via a thin film hydration method or using cyclodextrin-functionalized PAOx. Here, we report the mechanochemical preparation of defined and stable C60:PAOx NPs by the introduction of a simple alkyne group as a polymer end-group. The presence of this alkyne bond is proven to be crucial in the mechanochemical synthesis of stable, defined sub-100 nm C60:PAOx NPs, with high C60 content up to 8.9 wt %.