Accessibility of the pores in highly porous alumina films synthesized via sequential infiltration synthesis

She, Yunlong; Lee, Jihyung; Diroll, Benjamin T.; Scharf, Thomas; Shevchenko, Elena V.; Berman, Diana

doi:10.1088/1361-6528/aae144

Cited by 17 publications

(20 citation statements)

References 48 publications

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“…It has been demonstrated that graphene can be used to limit water access to the porosity of a highly adsorbing ceramic sponge. [72] This allows for the elimination of the effect of humid environments on the sliding behavior of materials protected by 2D materials. Additionally, the high mechanical stability of 2D materials is an extremely important parameter defining their survivability in mechanical/tribological contacts.…”

Section: Beneficial Mechanical and Tribological Propertiesmentioning

confidence: 99%

Layered 2D Nanomaterials to Tailor Friction and Wear in Machine Elements—A Review

Marian

Berman

Rota

et al. 2021

Adv Materials Inter

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122

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prominent members being molybdenum disulfide (MoS 2 ) and tungsten disulfide (WS 2 ). [2] In addition to graphene-and TMD-based nanomaterials, new 2D nanomaterials [3] such as silicenes, [4] hexagonal boron nitride (h-BN), [5] black phosphorous (BP), [6,7] halide structures, [8] metal-organic framework nanosheets, [9] and MXenes [10,11] are currently optimized regarding their synthesis methods and expectable yield. The coupling of excellent electrical and thermal conductivity with great mechanical properties, high surface-to-volume ratios, and the existence of surface terminations, which enable their chemical functionalization, has made these 2D nanomaterials promising candidates to be used in different applications such as energy storage devices and supercapacitors, [12] (photo)-catalysis, [13] water purification, [14] and tribological systems. [15][16][17][18] In the tribological context, 2D layered structures showed their great potential in improving friction and wear of various substrate materials under dry and lubricated conditions. With respect to the lubricated conditions, 2D materials are typically used as lubricant additives in base oils with the overall purpose to fulfill different functions in the contact area. During sliding, nanomaterials may act both as shearing films and nano-roller bearings, thus potentially changing the friction mode from sliding to rolling friction and regulating the resulting lubricant flow, thus reducing frictional losses. [19] Irrespective of the prevalence of dry or lubricated conditions, 2D materials may be capable of initiating tribo-chemical reactions in the contact area Recent advances in 2D nanomaterials, such as graphene, transition metal dichalcogenides, boron nitride, MXenes, allow not only to discover several new nanoscale phenomena but also to address the scientific and industrial challenges associated with the design of systems with desired physical properties. One of the great challenges for mechanical systems is associated with addressing friction and wear problems in machine elements. In this review, the beneficial properties of layered 2D materials that enable the control of their tribological behavior and make them excellent candidates for efficient friction and wear reduction in dry-running and boundary lubricated machine components are summarized. The recent studies highlighting the successful implementation of 2D structures when used as solid lubricant coatings or reinforcement phases in composites for various machine components including sliding and rolling bearings, gears, and seals are overviewed. The examples presented in the studies demonstrate the great potential for 2D materials to address the energy-saving needs by friction and wear reduction.

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Section: Beneficial Mechanical and Tribological Propertiesmentioning

confidence: 99%

Layered 2D Nanomaterials to Tailor Friction and Wear in Machine Elements—A Review

Marian

Berman

Rota

et al. 2021

Adv Materials Inter

Self Cite

122

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“…Stepwise exposure of the polymer film to vapors of trimethylaluminum (TMA) and water results in the growth of aluminum oxide structure inside the polar domain, vinyl pyridine, of the polymer matrix. The structure of the aluminum oxide, after removal of the polymer template in an oxygen atmosphere at an elevated temperature (400 • C) is amorphous (She et al, 2018). For the liquid levitation experiments, single crystal corundum (Al 2 O 3 ) beads of 3mm diameter and 99.99% purity were used as starting material.…”

Section: Sample Synthesismentioning

confidence: 99%

The Structure of Amorphous and Deeply Supercooled Liquid Alumina

et al. 2019

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Liquid Al 2 O 3 has been supercooled more than 500 K below its melting point (T m = 2,327 K) using aerodynamic levitation and laser heating techniques. High energy synchrotron x-ray measurements were performed over a temperature range of 1,817 ≤ T (K) ≤ 2,700 and stroboscopic neutron diffraction at 1,984 and 2,587 K. The diffraction patterns have been fitted with Empirical Potential Structure Refinement (EPSR) models and compared to classical Molecular Dynamics (MD) simulation results. Both sets of models show similar trends, indicating the presence of high populations of AlO 4 and AlO 5 polyhedral units predominantly linked by triply shared oxygen atoms. EPSR reveals that the mean Al-O coordination number changes linearly with temperature with n AlO = 4.41-[1.25 × 10 −4 ] (T-T m), with a 2.5 Å cutoff. Both EPSR and MD simulations reveal a direction of the temperature dependence of the aluminate network structure which moves further away from the glass forming ideal (n AlO = 3) during supercooling. Furthermore, we provide new experimental data and models for amorphous alumina grown by sequential infiltration synthesis of a polymer template. The amorphous solid form likely has a larger Al-O coordination number than the liquid, consistent with expectations for the hypothetical glass.

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“…This longer exposure allows the precursors to diffuse into the polymer substrates rather than simply decorating the surface [2][3][4] . SIS allows transforming polymers into organicinorganic hybrid materials: penetration and reaction of gaseous metal precursors into polymer, during SIS, permit to grow inorganic materials into polymeric films [5] in order to tune some of their features as their optical properties or improve their chemical etch resistance [6][7][8][9] .…”

Section: Introductionmentioning

confidence: 99%

Effect of the Density of Reactive Sites in P(S‐r‐MMA) Film during Al₂O₃ Growth by Sequential Infiltration Synthesis

Caligiore¹,

Nazzari

Cianci³

et al. 2019

Adv Materials Inter

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than simply decorating the surface. [2][3][4] SIS allows transforming polymers into organic-inorganic hybrid materials: penetration and reaction of gaseous metal precursors into polymer, during SIS, permit to grow inorganic materials into polymeric films [5] in order to tune some of their features as their optical properties or improve their chemical etch resistance. [6][7][8][9] The SIS process is characterized by two factors: diffusion and entrapment of precursor molecules into the polymer matrix. The most direct method to promote their entrapment is the chemical reaction of penetrant molecules with polymer functional groups in combination with a secondary precursor (coreactant). [4] Thus, the number of reactive sites within the polymer film plays an important role in the determination of the amount of inorganic material grown in the film during the process. Moreover, differently from ALD, the self-terminating reactions are not restricted to the surface sites. Precursor molecules must diffuse into the polymeric film to reach the reactive sites that are distributed in the volume of the polymeric matrix. Consequently, diffusion plays a fundamental part in the kinetics of the infiltration process and needs to be monitored in real time. The most used in situ techniques for investigating the infiltration mechanism are in situ quartz crystal microbalance (QCM) measurements and in situ Fourier transform infrared (FTIR) spectroscopy. [10][11][12][13] In situ dynamic spectroscopic ellipsometry (SE) was recently validated as a valuable tool for real time investigation of the infiltration process in poly(methyl methacrylate) (PMMA) and polystyrene (PS) homopolymers. [14] In situ SE is a noninvasive optical technique frequently used in combination with ALD processes [15][16][17] and for studies of polymer films under several conditions. [18][19][20] During SIS process, in situ SE allows continuous acquisition of information about changes of thickness and refractive index (n) of polymer films without interrupting the process itself on a shorter time scale than in situ FTIR spectroscopic analysis and without the need of ad hoc samples as for QCM measurements. When SIS is performed into self-assembled block copolymers (BCP), [21] the selective binding of precursors to one domain only of BCPs offers the possibility to fabricate inorganic functional nanoarchitectures [22] or hard masks for lithography. [23] Removing polymers by O 2 plasma after Sequential infiltration synthesis (SIS) consists in a controlled sequence of metal organic precursors and coreactant vapor exposure cycles of polymer films. Two aspects characterize an SIS process: precursor molecule diffusion within the polymer matrix and precursor molecule entrapment into polymer films via chemical reaction. In this paper, SIS process for the alumina synthesis is investigated using trimethylaluminum (TMA) and H 2 O in thin films of poly(styrene-random-methyl methacrylate) (P(S-r-MMA)) with variable MMA content. The amount of alumina grown in the P(S-r-MMA) films linear...

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Accessibility of the pores in highly porous alumina films synthesized via sequential infiltration synthesis

Cited by 17 publications

References 48 publications

Layered 2D Nanomaterials to Tailor Friction and Wear in Machine Elements—A Review

Layered 2D Nanomaterials to Tailor Friction and Wear in Machine Elements—A Review

The Structure of Amorphous and Deeply Supercooled Liquid Alumina

Effect of the Density of Reactive Sites in P(S‐r‐MMA) Film during Al₂O₃ Growth by Sequential Infiltration Synthesis

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Accessibility of the pores in highly porous alumina films synthesized via sequential infiltration synthesis

Cited by 17 publications

References 48 publications

Layered 2D Nanomaterials to Tailor Friction and Wear in Machine Elements—A Review

Layered 2D Nanomaterials to Tailor Friction and Wear in Machine Elements—A Review

The Structure of Amorphous and Deeply Supercooled Liquid Alumina

Effect of the Density of Reactive Sites in P(S‐r‐MMA) Film during Al2O3 Growth by Sequential Infiltration Synthesis

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Product

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Effect of the Density of Reactive Sites in P(S‐r‐MMA) Film during Al₂O₃ Growth by Sequential Infiltration Synthesis