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Dynamic surface properties of fullerenol solutions Boris A. Noskov, Kirill Timoshen, Alexander V. Akentiev, Nikolay S. Chirkov, Ignat Dubovsky, Vasili Lebedev, Shi-Yow Lin, Giuseppe Loglio, Reinhard Miller, Victor Sedov, and Alina Borisenkova Langmuir, Just Accepted Manuscript • DOI: 10.1021/acs.langmuir.8b04152 • Publication Date (Web): 14 Feb 2019 Downloaded from http://pubs.acs.org on February 16, 2019
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Dynamic surface properties of fullerenol solutions Boris A. Noskov1*, Kirill A. Timoshen.1, Alexander V. Akentiev1, Nikolay S. Chirkov1, Ignat M. Dubovsky5, Vasyli T. Lebedev.5, Shi-Yow Lin.2, Giuseppe Loglio3, Reinhard Miller4,Victor P. Sedov5, Alina A. Borisenkova5 1St.
Petersburg State University, 26 Universitetskiy pr., Petergof, St. Petersburg, 198504, Russia Taiwan University of Science and Technology, Chemical Engineering Department, 43 Keelung Road, Section 4, 106 Taipei, Taiwan 3Institute of Condensed Matter Chemistry and Technologies for Energy, 16149 Genoa, Italy 4 MPI für Kolloid- und Grenzflächenforschung, Wissenschaftspark Golm, D-14424 Golm, Germany 5B.P. Konstantinov Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, 188300 Gatchina, Leningrad distr., Russia
2 National
Keywords: fullerenol solutions, surface properties, dynamic surface elasticity, atomic force microscopy, adsorption kinetics Application of the dilational surface rheology, surface tensiometry, ellipsometry, Brewster angle, transmission electron and atomic force microscopies allowed estimation of the structure of the adsorption layer of a fullerenol with a large number of hydroxyl groups, C60(OH)X (X = 30 ±2). The surface properties of fullerenol solutions proved to be similar to the properties of dispersions of solid nanoparticles and differ from those of the solutions of conventional surfactants and amphiphilic macromolecules. Although the surface activity of fullerenol is not high, it forms adsorption layers of high surface elasticity up to 170 mN/m. The layer consists of small interconnected surface aggregates with the thickness corresponding to two – three layers of fullerenol molecules. The aggregates are not adsorbed from the bulk phase but formed at the interface. The adsorption kinetics is controlled by an electrostatic adsorption barrier at the interface.
1. Introduction The broad application of fullerenes in various branches of industry and medicine is a consequence of their unique properties. Nowadays numerous reviews discuss different aspects of these applications 1–6. At the same time, the extremely low solubility of pristine fullerenes in water restrains seriously their direct use for medical purposes. Another problem of their technological applications consists in the difficulty of formation of regular thin surface films of these substances. The conventional Langmuir – Blodgett technique based on the monolayer or multilayer transfer from the surface of water onto a solid support is not suitable for the preparation of fullerene layers because these substances do not form stable monolayers at the water – air interface. The spreading of fullerene from organic solvents onto the water surface results in heterogeneous and very fragile layers of variable thickness7,8. To overcome this problem one can use the chemical modificationof fullerenes. The most frequently applied *
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fullerene derivatives are also insoluble in water but can be spread along the surface leading to the formation of more homogeneous layers 9–11. Only recently it has been shown that water soluble derivatives of C60 fullerene with arginine and lysine possess surface activity, and thereby form spontaneously macroscopically homogeneous adsorption layers at the water – air interface 12. Polyhydroxylated fullerenes, or fullerenols, take a special place in a relatively small group of water soluble fullerene derivatives. The fullerenols have a relatively simple structure and it is possible to change their solubility from almost zero up to about 60 g/l at room temperature by increasing the number of hydroxyl groups13. They are characterized by high adhesion to metals and semiconductors, form thin films on their surfaces, and thereby can be used in micro- and optoelectronics14. On the other hand, fullerenols improve mechanical properties of materials and are applied as modifiers of concretes and paints15. The most important are probably medical applications of fullerenols. Their antioxidative properties and free radical scavenging effects have been known for more than twenty years15–17. Later their radioprotective effect has been discovered15,18. Other studies indicated antitumor and antimetastatic activities of fullerenols15,19. The amphiphilic nature of fullerenols with a relatively small number of hydroxyl groups results in their surface activity. Liu et al. observed adsorption of slightly soluble C60(OH)12 fullerenol at the aqueous solution – air interface in a few hours after surface formation and studied the compression isotherm of this adsorption layer20. Later Rincon et al. prepared spread layers of slightly soluble fullerenols at the water surface and applied the Langmuir-Blodgett method to study optical and electrical properties of their films on glass and polyaniline substrates21. At the same time, to the best of our knowledge there is no information on the adsorption of highly soluble fullerenols at the solution – air interface. A probable reason is that soluble fullerene derivatives decrease the surface tension of water only slightly, even at high concentrationsof about 1 g/l. Only recently, it has been shown that in spite of low surface pressure the adsorption layer of the C60-arginine fullerene derivative is characterized by a high surface dilational elasticity (~ 100 mN/m) and, therefore, can be used for the formation of stable Langmuir-Blodgett structures12. The main aim of the given work is to study the surface properties of solutions of fullerenols with a high number of hydroxyl groups and to check the possibility of the formation of a robust adsorption layer at the water-air interface. 2. Experimental section Preparation of fullerenol C60(OH)X (X=30±2).The preparation of hydroxylated fullerenes consisted of two main steps. At the first step water-insoluble and low-hydroxylated fullerenols were prepared by a reaction of fullerenes dissolved in o-xylene with ammonia aqueous solution containing tetrabutylammonium hydroxide (TBAG) as an interfacial transfer catalyst in an anaerobic atmosphere at slight heating of the reaction mixture. High-purity fullerenes were used for this aim22. In the course of this reaction (~ 24 hours) a complete decoloration of the fullerene solution and a formation of a black suspension in o-xylene coexisting with a colorless mineral phase (ammonia aqueous solution with TBAG) have been observed. The solid fractions were separated, washed with pure o-xylene to remove not reacted fullerene and dried under vacuum at 400 C for about 3 hours. Low-hydroxylated fullerenols insoluble in o-xylene and water displayed IR-spectra with transmission bands characteristic for fullerenols. In the second step, the obtained low hydroxylated fullerenols in the form of an aqueous solution with hydrogen peroxide were subjected to hydroxylation at a temperature of 65-70 °C in an anaerobic atmosphere while stirring.The hydroxylation took place for a relatively short time (1.5-4 hours) with the formation of a transparent solution of fullerenols. ACS Paragon Plus Environment
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After that, the solution was steamed and added to a 10-fold volume of the precipitation mixture (isopropanol:heptane = 70 : 30) to precipitate the product. The solid precipitate was separated by centrifugation and washed twice with a small amount of the precipitation mixture to remove residual hydrogen peroxide. The thermal analysis (Laboratory tube furnace SNOL 0.2/1250 with programmable thermostat, SNOL Term, Russia) showed that fullerenol molecules contained X = 30 ±2 hydroxyl groups23. The elemental analysis (EuroVector Euro EA3028-HT, Italy) showed 28 hydroxyl groups per fullerenol molecule. Thus, the data of both measurements are in good agreement. Figure 1 shows the corresponding IR-spectrum that is a transmitted intensity vs. wave numbers (FTIR-spectrometer FSM 1201 LLS “Monitoring”, Russia). The IR-spectrum has the bands proving the presence of hydroxyl groups attached to the fullerene cage. The band at 1620 cm-1 corresponds to stretching vibrations of C-O, weak bands at 1081 cm-1 and 1390 cm-1 should be attributed to the deformation vibrations of bound of C-O-H groups. The band at 1724 cm-1 refer to the vibrations of С-С bonds in fullerenols, and the intense band at 3281 cm-1 must be related to the oscillations of a hydroxyl group linked with a cage. All the solutions of fullerene derivatives were prepared in triply distilled water. An apparatus made from glass was used during the last two steps of distillation. Methods. The surface tension was measured by the Wilhelmy plate method using a roughened glass plate attached to an electronic balance. The complex dynamic surface elasticity was measured by the oscillating barrier method at a fixed frequency of 0.1 Hz. The corresponding experimental equipment and procedures were described in detail elsewhere24. The oscillations of the solution surface area in a polytetrafluoroethylene (PTFE) Langmuir trough were produced by a movable PTFE barrier sliding along the polished brims of the trough. A mechanical generator transformed the rotation of an electric motor into the translational motion with reversion and allowed control of the oscillation amplitude and frequency. The moving part of the generator was connected to the barrier by a steel rod. The barrier glided back and forth along the Langmuir trough and produced oscillations of the liquid surface area A. The oscillation amplitude can be changed from 2.5 up to7.5 %. The induced oscillations of the surface tension γ were measured by the Wilhelmy plate method The complex dynamic surface elasticity ε was calculated according to the following relationship ε(ω) = δγ/δlnA where δγ and δA are the increments of the surface tension and surface area, respectively. If the phase shift between the oscillations of surface area and surface tension is known, it is possible to determine the real and imaginary parts of the dynamic surface elasticity, which is in general a complex quantity. The relative error of the determination of the real part of the dynamic surface elasticity was about ± 5 %. The imaginary part of the complex dynamic surface elasticity of the solutions under investigation proved to be much less than the real part. Therefore, only the results for the real part are discussed below. The Langmuir trough was placed in a cabinet made from Plexiglas with small holes for the steel rood and glass plate to minimize evaporation of the solution. Measurements of the surface tension of pure water showed that the decrease of water level in the trough during two days led only to errors less than 0.5 mN/m in the surface tension and in the dynamic surface elasticity. All the measurements of the dynamic surface properties were started after purification of the surface using a movable barrier on the surface of the Langmuir trough and a Pasteur pipette connected with a pump. All the measurements were performed at a temperature of 20±1◦C. The macroscopic morphology of the adsorption layers of fullerene derivatives was investigated in situ by the Brewster angle microscope BAM1 (NFT, Göttingen, Germany) ACS Paragon Plus Environment
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equipped with a 10mW He-Ne laser. The solution under investigation was placed in the Langmuir through and equilibrated at room temperature for a few hours before images were obtained. The adsorption C60(OH)X (X=30±2) films were transferred from the solution surface onto a freshly cleaved mica plate by the Langmuir–Schäfer technique and investigated by AFM using NTEGRA Prima setup (NT-MDT, Russia) with the aim to determine the microscopic morphology of the film. The tip curvature radius was about 10 nm. The mica plate with the transferred adsorption layer was stored for a few days in a desiccator. The semi contact regime was used for all the measurements. The software NOVA was used in the course of microscope operation and image analysis. A null-ellipsometer Multiskop (Optrel, Germany) at a single wavelength of 632.8 nm was applied to estimate the adsorbed amount using a fixed compensator (45°) and a 2-zone averaging nulling scheme. All the ellipsometric measurements were performed at an incidence angle of 50° close to the Brewster angle. In the model of a thin isotropic layer of uniform density between the liquid and gas phases the difference Δsurf between the ellipsometric angle Δ for the investigated solution and that of pure water Δ0 is proportional to the surface concentration25. Therefore, we present below only data on the ellipsometric angle Δ to characterize the adsorption kinetics. The aggregation of C60(OH)X (X=30±2) in the bulk of aqueous solutions was studied by transmission electron microscopy (TEM). A copper grid coated with a thin nitrocellulose film was used as a substrate in the TEM studies. A droplet of fullerenol solution was spread onto the substrate and dried for a few days. The zeta potential of C60(OH)X (X=30±2) in investigated solutions was determined by the dynamic light scattering (DLS) using a Zetasizer ZS Nano analyzer (Malvern Instruments, United Kingdom). The measurements were carried out at a scattering angle of 173. 3. Results and discussion The application of TEM did allow the observation of a noticeable number of dense compact aggregates in dilute aqueous solutions of C60(OH)X (X=30±2). Figure 2 shows as an example a micrograph of a fullerenol film on the surface of nitrocellulose. The film was formed as a result of drying of a drop of fullerenol solution with concentration of 0.2 g/l. One can observe that the largest part of the area in Figure 2 is covered by a loose structure of interconnected irregular dark spots. The number of spots increases in the direction from the upper right corner to the lower left corner. This is the direction of the retraction of a solution drop in the process of drying. The upper right corner of Figure 2 is brighter and more homogeneous. Nevertheless, even in this part one can observe some spots slightly darker than the bright thin elongated regions between them. The characteristic size of the spots in this area is of the order of 20 nm. The morphology of the surface in the upper left corner differs from the more homogeneous surface of nitrocellulose and probably corresponds to a monolayer of C60(OH)X (X=30±2) with cracks formed in the process of drying. The mean thickness of the layer increases in the direction to the lower right corner where the dark spots can correspond to patches of the multilayers. Note that the morphology of the film in Figure 2 differs strongly from that of Langmuir –Schäfer films on the surface of mica (cf. below). In some micrographs one could observe relatively dense aggregates with the mean size of about 100 nm like that in the upper part of Figure 2. These rare aggregates cannot influence the surface properties of the solutions under investigation The surface pressure of a 0.1 g/l fullerenol solution is zero within the error limits for more than one day after the surface formation and it starts to increase noticeably with the surface ACS Paragon Plus Environment
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age at higher concentrations only (Figure 3). Similar behavior is characteristic for the dynamic dilation surface elasticity (Figure 4). At the concentration of 0.5 g/l one can observe an induction period when the surface elasticity almost does not change for about two hours and increases significantly thereafter. This effect is an indirect indication of the heterogeneity of the adsorption layer at the beginning of adsorption when the adsorbed molecules form small islands of a surface condensed phase and the surface elasticity starts to increase only when the size and/or number of the islands increases and they start to interact26. After these initial changes, the surface properties continue to increase for about one day, go through a maximum and decrease at longer times (Figures 3, 4). While the surface pressure does not exceed 9 mN/m, the surface elasticity at the oscillation amplitude of 7.5 % and a frequency of 0.1 Hz can reach rather high values up to about 140 mN/m at concentrations higher than about 0.2 g/l. The non-monotonic changes of surface properties (Figures 3, 4) are obviously caused by a break in the course of oscillations of the surface area. The beginning of the decrease of surface properties coincides with the switching on of the oscillations after the break. The decrease of the surface pressure and dynamic surface elasticity under the influence of surface area oscillations is a characteristic feature for adsorbed layers of solid nanoparticles and to the best of our knowledge is not observed in the course of adsorption of conventional surfactants, amphiphilic macromolecules and soft nanoparticles27,28. This effect is caused by partial destruction of a fragile adsorption layer structure under the influence of external mechanical perturbations leading to the formation of some patches of multilayers and to a decrease of the surface elasticity. The concomitant decrease of the number of hydrophobic groups in the proximal region of the surface layers can result in a surface tension increase.The strong drop of surface properties after the maximum was not observed for the layers of fullerene derivatives with arginine and lysine where the fullerene core was enclosed by a thin corona of amino acid residues12. It is a characteristic feature of fullerenol layers indicating the higher sensitivity of the layers to mechanical perturbations. This effect was weaker for complexes of silica nanoparticles with an oppositely charged surfactant where one can assume a higher attraction between the particles in the surface layer 27. The compression of the adsorbed layer in the Langmuir trough results in an abrupt increase of the surface pressure and dynamic surface elasticity with a subsequent relaxation for more than one hour. At the approach to equilibrium, the surface properties do not reach their values before the compression indicating the increase of surface concentration. The relaxation of surface properties is probably not caused by the desorption of adsorbed fullerenols but by some structural rearrangement leading to a more compact packing in the surface layer. The substitution of fullerenol solution in the sub-phase by pure water does not result in noticeable changes of the surface properties showing that the adsorption is irreversible. The dynamic surface elasticity decreases strongly with the increase of the surface area amplitude from 2.5 to 7.5% and the range of oscillation amplitudes corresponding to a linear response of the system to surface dilation corresponds to lower deformations (Figure 5). Note that these data correspond to continuous oscillations of the barrier unlike the results in Figures 3 and 4 when the oscillations were switched off during the intervals between the measurements of the dynamic surface elasticity. Rather unexpectedly, the surface pressure also decreases when the amplitude reaches 7.5 %. These results are obviously a consequence of significant structural rearrangements in the adsorption layer even at slight external perturbations. The oscillations of higher amplitude lead to a stronger destruction of the adsorption layer, to a larger number of cracks and multilayer aggregates in it, and thereby to the lower dynamic surface elasticity and even lower surface pressure.
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The high sensitivity of the adsorption layer to slight mechanical perturbations leads to the influence of the total time of surface area oscillations on the kinetic dependencies of the dynamic surface elasticity. The surface elasticity increases faster for a few hours after the surface formation if the area oscillations are switched off between the measurements, approximately for every 30 minutes. The influence of the time of surface area oscillations on the kinetic dependencies of surface properties can be more complicated at longer measurements. The assumed microscopic heterogeneity of C60(OH)X (X=30±2) adsorption layers does not influence their macroscopic morphology and the Brewster angle microscopy shows only a homogeneous surface of fullerenol solutions even in 48 hours after the surface formation (Fig. 6a). The abrupt surface compression does not lead to any visible deformations of the adsorption layer but a slight touch of the surface by a thin stick results in noticeable changes of the surface morphology just after the perturbation (Fig. 6b). The adsorbed layer recovers its continuity during the next few minutes indicating liquid-like properties of the layer at the macroscopic scale. The surface concentration of fullerenols increases faster after surface formation than the dynamic surface elasticity and surface tension. The ellipsometric angle Δ equals the equilibrium value within the error limits for about 7 hours at the concentration of 0.2 g/l (Figure 7). This means that slight changes of the total surface concentration at the approach to equilibrium can result in significant changes of the surface elasticity due to the structural rearrangements in the surface layer. The ellipsometric signal fluctuates for more than three hours after the surface formation (Figure 7). One can connect these chaotic changes of the signal with the macroscopic heterogeneity of the adsorption layer, probably due to bilayer or multilayer formations, and with the fluidity of the layer at the first step of adsorption. The motion of macroscopic regions of the adsorption layer of different density close to the spot of the laser beam of the ellipsometer on the liquid surface can lead to these fluctuations, which rather abruptly disappear when the surface density reaches a certain critical value and the adsorption layer becomes immobile. Note that the sensitivity of the Brewster angle microscopy does not allow observations of the heterogeneity of the optical properties of the adsorption layer. Figure 7 shows that the characteristic adsorption time is of the order of few hours and much higher than the characteristic time τ of the surfactant diffusion from the bulk phase to the surface. One can estimate the latter quantity according to the following relation29
(Γ𝑐)
2
(1), 𝐷 where c is the bulk concentration, Г is the surface concentration (adsorbed amount), and D is the diffusion coefficient. The diffusion coefficient of C60(OH)X (X=30±2) fullerenol can be calculated from the particle radius R using the Stokes – Einstein equation. Semenov et al. estimated R = 6.5 Å for C60(OH)3014. This gives D =3.2910-10 m2s-1. If the fullerenols form a monolayer with the most compact packing at the interface, one can use the following relation for the surface concentration 𝑚 Γ = 𝜋𝑅2 (2), where m = 1230 a.m.u. is the mass of a fullerenol molecule and = 1.102 is the coefficient corresponding to the densest packing of circles in the plane. The calculations according to relations (1) and (2) give τ = 0.15 s at c = 0.2 g/l. This is only a rough estimate because of the assumptions made on the formation of a compact fullerenol
𝜏=
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monolayer at the interface and on the adsorption of separate molecules. However, the violation of the former assumption cannot lead to changes of τ by more than an order of magnitude and the latter assumption also seems reasonable because one can neglect the concentration of large aggregates (cf. Figure 2). At the same time, the calculated value is a few orders of magnitude less than the estimation from the data in Figure 7, and therefore indicates that the fullerenol adsorption is not controlled by diffusion. The discovered retardation of the adsorption can be caused by an electrostatic adsorption barrier due to the negative charge of C60(OH)X (X=30±2) as indicated by the zeta potential, which is -42 2 mV in the concentration range under investigation. The first adsorbed molecules create an electric field leading to the repulsion of the adsorbing molecules of similar charge. Although the pH of the solution decreased with the increase of concentration, the corresponding changes of the zeta potential were in the error limits. To investigate the structure of the fullerenol adsorption layers they were transferred from the liquid surface onto the freshly cleaved surface of mica by the Langmuir–Schäfer method and investigated by AFM. Arrows in Figure 8 show the values of surface properties at the moment of layer transfer from the surface of a 0.5 g/l solution and Figure 9 presents the corresponding AFM images. In about an hour after the surface formation the layer consists of interconnected aggregates with the thickness of 2 – 3 nm and some empty spots on the mica surface (Figure 9a). AFM does not allow reliable estimates of the width of the aggregates but it is higher than the thickness and therefore the surface aggregates are some patches of bilayers and triple layers. The direct comparison of AFM images with the micrograph in Figure 2 is difficult because of the different physical principles of the two methods. A reliable conclusion is that the holes in Figure 9a are much larger than the gaps between grey spots in the upper right corner of Figure 2. On the other hand, the thickness of the surface aggregates in Figure 9a is probably larger than the thickness of the grey patches in Figure 2, and they are not the same objects. Therefore, the aggregates in the adsorption layer at the liquid – gas interface are not adsorbed from the bulk phase but formed in the surface layer as a result of the rearrangements of adsorbed molecules. In about one day after the surface formation the adsorption layer becomes denser (Figure 9b) but preserves the main features of the structure. The layer consists of a large number of small aggregates with some holes between them. In this case the dynamic surface elasticity is approximately two times higher than the value corresponding to Figure 9а. The obtained results show that fullerenol molecules do not form a monolayer at the water – air interface but rather a monolayer of small aggregates. Nevertheless, these aggregates can be easily transferred onto a solid support and form a dense layer on it. If the adsorption layer is subjected to continuous oscillations of the surface area for more than one hour the continuous structure of the layer is destroyed into pieces and one can observe cracks of different width in the layer and dense patches between them (Figure 9c), in agreement with the conclusions from measurements of the dynamic surface elasticity. In this case the surface elasticity drops from about 125 to 65 mN/m, and the surface pressure also decreases (see Figure 8). 4. Conclusions Although the surface activity of fullerenols with a great number of hydroxyl groups is not high and these substances do not decrease significantly the surface tension at low concentrations, the fullerenol molecules form a macroscopically homogeneous adsorption layer at the solution – air interface with high dynamic surface elasticity values up to 170 mN/m. In spite of the relatively low molecular mass of the fullerenol, the surface properties of its solutions resemble ACS Paragon Plus Environment
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rather those of dispersions of solid nanoparticles than of surfactant solutions and are very sensitive to slight mechanical perturbations of the surface. As a result, the adsorption layer is characterized by a non-linear response even to slight oscillations of the surface area. These oscillations can lead to the destruction of the continuous surface structure, and the formation of cracks between dense patches of the layer. AFM shows that the adsorption layer is not homogeneous at the microscale and consists of interconnected surface micro-aggregates consisting of two – three layers of fullerenol molecules. The bonds between different aggregates are weak and they can be broken even at slight mechanical perturbations although the whole structure is characterized by a strong response to dilation (high surface elasticity). The surface aggregates are not adsorbed form the bulk phase but formed in the surface layer as a result of structural rearrangements of the adsorbed molecules. The slow fullerenol adsorption is not controlled by diffusion but by an electrostatic adsorption barrier. Acknowledgements. The groups from SPSU and from B.P.Konstantinov Petersburg Nuclear Physics Institute were financially supported by RFBR, project № 18-29-19100 (SPSU) and project № 18-29-19008 (PNPI). The authors are also grateful to the Center for Chemical Analysis and Materials Research of SPSU for assistance with the fullerenol elemental analysis. References: (1) Kang, H.; Lee, W.; Oh, J.; Kim, T.; Lee, C.; Kim, B. J. From Fullerene-Polymer to AllPolymer Solar Cells: The Importance of Molecular Packing, Orientation, and Morphology Control. Acc Chem Res 2016, 49 (11), 2424–2434. (2) Dini, D.; Calvete, M. J. F.; Hanack, M. Nonlinear Optical Materials for the Smart Filtering of Optical Radiation. Chem Rev 2016, 116 (22), 13043–13233. (3) Richter, M.; Heumueller, T.; Matt, G. J.; Heiss, W.; Brabec, C. J. Carbon Photodetectors: The Versatility of Carbon Allotropes. Adv Energy Mater 2017, 7 (10), 1601574. (4) Goodarzi, S.; Da Ros, T.; Conde, J.; Sefat, F.; Mozafari, M. Fullerene: Biomedical Engineers Get to Revisit an Old Friend. Mater Today 2017, 20 (8), 460–480. (5) Castro, E.; Garcia, A. H.; Zavala, G.; Echegoyen, L. Fullerenes in Biology and Medicine. J Mater Chem B 2017, 5 (32), 6523–6535. (6) Zieleniewska, A.; Lodermeyer, F.; Roth, A.; Guldi, D. M. Fullerenes – How 25 Years of Charge Transfer Chemistry Have Shaped Our Understanding of (Interfacial) Interactions. Chem Soc Rev 2018, 47 (3), 702–714. (7) Evans, A. K. Kinetics of Langmuir Films of Fullerene C60. J Phys Chem B 1998, 102 (36), 7016–7022. (8) Kolker, A. M.; Borovkov, N. Y. Three-Dimensional Aggregation of Fullerene C60at the Air-Water Interface. Colloids Surfaces A Physicochem Eng Asp 2012, 414, 433–439. (9) Burghardt, S.; Hirsch, A.; Medard, N.; Kachfhe, R. A.; Ausseré, D.; Valignat, M. P.; Gallani, J. L. Preparation of Highly Stable Organic Steps with a Fullerene-Based Molecule. Langmuir 2005, 21 (16), 7540–7544. (10) Fujii, S.; Morita, T.; Kimura, S. Fabrication of Langmuir-Blodgett Film of a Fullerene Derivative with a Cyclic Peptide as an Anchor. Bioconjug Chem 2007, 18 (6), 1855–1859. (11) Álvarez-Venicio, V.; Gutiérrez-Nava, M.; Amelines-Sarria, O.; Álvarez-Zauco, E.; Basiuk, V. A.; Carreón-Castro, M. P. Incorporation in Langmuir-Blodgett Films of an Amphiphilic Derivative of Fullerene C60 and Oligo-Para-Phenylenevinylene. Thin Solid Films 2012, 526, 246–251. (12) Noskov, B. A.; Timoshen, K. A.; Akentiev, A. V; Charykov, N. A.; Loglio, G.; Miller, R.; Semenov, K. N. Dynamic Surface Properties of C 60 -Arginine and C 60 - L -Lysine Aqueous Solutions. Colloids Surfaces A 2017, 529, 1–6. ACS Paragon Plus Environment
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(13) (14) (15) (16) (17) (18) (19)
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Chaban, V. V.; Fileti, E. E. Which Fullerenols Are Water Soluble? Systematic Atomistic Investigation. New J Chem 2017, 41 (1), 184–189. Semenov, K. N.; Charykov, N. A.; Keskinov, V. N. Fullerenol Synthesis and Identification. Properties of the Fullerenol Water Solutions. J Chem Eng Data 2011, 56 (2), 230–239. Semenov, K. N.; Charykov, N. A.; Postnov, V. N.; Sharoyko, V. V.; Vorotyntsev, I. V.; Galagudza, M. M.; Murin, I. V. Fullerenols: Physicochemical Properties and Applications. Prog Solid State Chem 2016, 44 (2), 59–74. Tsai, M. C.; Chen, Y. H.; Chiang, L. Y. Polyhydroxylated C60, Fullerenol, a Novel FreeRadical Trapper, Prevented Hydrogen Peroxide- and Cumene Hydroperoxide-Elicited Changes in Rat Hippocampus in-Vitro. J Pharm Pharmacol 1997, 49 (4), 438–445. Djordjevic, A.; Srdjenovic, B.; Seke, M.; Petrovic, D.; Injac, R.; Mrdjanovic, J. Review of Synthesis and Antioxidant Potential of Fullerenol Nanoparticles. J Nanomater 2015, 2015, 15. Krokosz, A.; Lichota, A.; Nowak, K. E.; Grebowski, J. Carbon Nanoparticles as Possible Radioprotectors in Biological Systems. Radiat Phys Chem 2016, 128, 143–150. Liang, X.-J. J.; Meng, H.; Wang, Y.; He, H.; Meng, J.; Lu, J.; Wang, P. C.; Zhao, Y.; Gao, X.; Sun, B.; et al. Metallofullerene Nanoparticles Circumvent Tumor Resistance to Cisplatin by Reactivating Endocytosis. TL - 107. Proc Natl Acad Sci U S A 2010, 107 (16), 7449–7454. Liu, W.; Jeng, U.; Lin, T.; Lai, S.; Shih, M. C.; Tsao, C.; Wang, L. Y.; Chiang, L. Y.; Sung, L. P. Adsorption of Dodecahydroxylated-Fullerene Monolayers at the Air - Water Interface. Phys B 2000, 283, 49–52. Rincón, M. E.; Hu, H.; Campos, J.; Ruiz-García, J. Electrical and Optical Properties of Fullerenol Langmuir-Blodgett Films Deposited on Polyaniline Substrates. J Phys Chem B 2003, 107 (17), 4111–4117. Grushko, Y. .; Sedov, V. P.; Kolesnik, S. G. Akentiev.Pdf. 2456233, 2012. Goswami, T. H.; Singh, R.; Alam, S.; Mathur, G. N. Thermal Analysis : A Unique Method to Estimate the Number of Substituents in Fullerene Derivatives. Thermochim Acta 2004, 419, 97–104. Noskov, B. A.; Loglio, G.; Miller, R. Dilational Surface Visco-Elasticity of Polyelectrolyte/Surfactant Solutions: Formation of Heterogeneous Adsorption Layers. Adv Colloid Interface Sci 2011, 168 (1–2), 179–197. Campbell, R. A.; Yanez Arteta, M.; Angus-Smyth, A.; Nylander, T.; Noskov, B. A.; Varga, I. Direct Impact of Nonequilibrium Aggregates on the Structure and Morphology of Pdadmac/SDS Layers at the Air/Water Interface. Langmuir 2014, 30 (29), 8664–8674. Campbell, R. A.; Tummino, A.; Varga, I.; Milyaeva, O. Y.; Krycki, M. M.; Lin, S.-Y.; Laux, V.; Haertlein, M.; Forsyth, V. T.; Noskov, B. A. Adsorption of Denaturated Lysozyme at the Air–Water Interface: Structure and Morphology. Langmuir 2018, 34, 5020−5029. Yazhgur, P. A.; Noskov, B. A.; Liggieri, L.; Lin, S.-Y.; Loglio, G.; Miller, R.; Ravera, F. Dynamic Properties of Mixed Nanoparticle/Surfactant Adsorption Layers. Soft Matter 2013, 9 (12), 3305–3314. Noskov, B. A. Protein Conformational Transitions at the Liquid-Gas Interface as Studied by Dilational Surface Rheology. Adv Colloid Interface Sci 2014, 206, 222–238. Noskov, B. A. Fast Adsorption at the Liquid-Gas Interface. Adv Colloid Interface Sci 1996, 69 (1–3), 63–129.
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Figure legends: Figure 1. IR-spectrum for C60(OH)X (X=30±2) fullerenols. Transmitted intensity T vs. wave numbers . Figure 2.TEM micrograph of a fullerenol C60(OH)X (X=30±2) film on the surface of a nitrocellulose layer. Figure 3. Kinetic dependencies of the surface pressure at continuous barrier oscillations and various concentrations of fullerenol C60(OH)X (X=30±2) solutions. The results for the concentration of 0.3 g/l equal zero until the surface age 500 min and not shown. Figure 4. Kinetic dependencies of the dynamic surface elasticity at continuous barrier oscillations and various concentrations of fullerenol C60(OH)X (X=30±2) solutions. Figure 5. Kinetic dependencies of the dynamic surface elasticity of a fullerenol C60(OH)X (X=30±2) solution at the concentration of 0.2 g/l and at various amplitudes of oscillations. The barrier did not oscillate between the measurements of the dynamic surface elasticity. Figure 6. BAM Images of a C60(OH)X (X=30±2) fullerenol film with a solution concentration of 1 g/l: a) in 48 hours after the surface formation; b) after the perturbation of the surface by a thin stick. Figure 7. Kinetic dependencies of ellipsometric angles Δ (black squares) and ψ (red circles) for fullerenol C60(OH)X (X=30±2) solution at concentration of 0.2 g/l. Figure 8. Kinetic dependencies of surface pressure (black squares) and dynamic surface elasticity (red circles) for fullerenol C60(OH)X (X=30±2) solution at the concentration of 0.5 g/l. Letters and thin arrows indicate the moments when the layer was transferred onto mica surface by the Langmuir-Schäfer method. Figure 9. AFM images of different samples of fullerenol C60(OH)X (X=30±2)film: a) in 70 minutes after the surface formation; b) in 16 hours after the surface formation without oscillations; c) after continuous oscillations for 75 minutes.
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Figures
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Figure 1. IR-spectrum for C60(OH)X (X=30±2) fullerenols. Transmitted intensity T vs. wave numbers .
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Figure 2. TEM micrograph of a fullerenol C60(OH)X (X=30±2) film on the surface of a nitrocellulose layer.
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Figure 3. Kinetic dependencies of the surface pressure at continuous barrier oscillations and various concentrations of fullerenol C60(OH)X (X=30±2) solutions. The results for the concentration of 0.3 g/l equal zero until the surface age 500 min and not shown.
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Figure 5. Kinetic dependencies of the dynamic surface elasticity of a fullerenol C60(OH)X (X=30±2) solution at the concentration of 0.2 g/l and at various amplitudes of oscillations. The barrier did not oscillate between the measurements of the dynamic surface elasticity.
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Figure 6. BAM Images of a C60(OH)X (X=30±2) fullerenol film with a solution concentration of 1 g/l: a) in 48 hours after the surface formation; b) after the perturbation of the surface by a thin stick.
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Figure 7. Kinetic dependencies of ellipsometric angles Δ (black squares) and ψ (red circles) for fullerenol C60(OH)X (X=30±2) solution at concentration of 0.2 g/l.
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Figure 8. Kinetic dependencies of surface pressure (black squares) and dynamic surface elasticity (red circles) for fullerenol C60(OH)X (X=30±2) solution at the concentration of 0.5 g/l. Letters and thin arrows indicate the moments when the layer was transferred onto mica surface by the Langmuir-Schäfer method.
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Figure 9. AFM images of different samples of fullerenol C60(OH)X (X=30±2) film: a) in 70 minutes after the surface formation; b) in 16 hours after the surface formation without oscillations; c) after continuous oscillations for 75 minutes.
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TOC
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