Thermal Transport in 3D Nanostructures Zhan, Haifei; Nie, Yihan; Chen, Yongnan ...
Advanced functional materials,
02/2020, Volume:
30, Issue:
8
Journal Article
Peer reviewed
Open access
This work summarizes the recent progress on the thermal transport properties of 3D nanostructures, with an emphasis on experimental results. Depending on the applications, different 3D nanostructures ...can be prepared or designed to either achieve a low thermal conductivity for thermal insulation or thermoelectric devices or a high thermal conductivity for thermal interface materials used in the continuing miniaturization of electronics. A broad range of 3D nanostructures are discussed, ranging from colloidal crystals/assemblies, array structures, holey structures, hierarchical structures, to 3D nanostructured fillers for metal matrix composites and polymer composites. Different factors that impact the thermal conductivity of these 3D structures are compared and analyzed. This work provides an overall understanding of the thermal transport properties of various 3D nanostructures, which will shed light on the thermal management at nanoscale.
Diverse 3D nanostructures are fabricated to meet specific thermal management purposes, including nanoarchitectures (such as colloidal assemblies and carbon nanotube arrays) and nanocomposites from polymer matrix or metal matrix. It is shown that the use of nanostructuring of materials is an effective strategy to modify the thermal conductivity of materials.
Gold nanoparticles (AuNPs) are promising materials for many bioapplications. However, upon contacting with biological media, AuNPs undergo changes. The interaction with proteins results in the ...so‐called protein corona (PC) around AuNPs, leading to the new bioidentity and optical properties. Understanding the mechanisms of PC formation and its functions can help us to utilise its benefits and avoid its drawbacks. To date, most of the previous works aimed to understand the mechanisms governing PC formation and focused on the spherical nanoparticles, although non‐spherical nanoparticles are designed for a wide range of applications in biosensing. In this work, we investigated the differences in PC formation on spherical and anisotropic AuNPs (nanostars in particular) from the joint experimental (extinction spectroscopy, zeta potential and surface‐enhanced Raman scattering SERS) and computational methods (the finite element method and molecular dynamics MD simulations). We discovered that protein does not fully cover the surface of anisotropic nanoparticles, leaving SERS hot‐spots at the tips and high curvature edges ‘available’ for analyte binding (no SERS signal after pre‐incubation with protein) while providing protein‐induced stabilization (indicated by extinction spectroscopy) of the AuNPs by providing a protein layer around the particle's core. The findings are confirmed from our MD simulations, the adsorption energy significantly decreases with the increased radius of curvature, so that tips (adsorption energy: 2762.334 kJ/mol) would be the least preferential binding site compared to core (adsorption energy: 11819.263 kJ/mol). These observations will help the development of new nanostructures with improved sensing and targeting ability.
Gold nanoparticles demonstrate unique, shape‐dependent protein interactions. The protein layers strongly adsorb onto the surface of the nanoparticles, which increases their stability. Protein does not entirely cover the surface of gold nanostars, but it provides stability with a protein layer around the core. These findings will support the creation of new nanostructures with enhanced sensing and targeting capabilities.
The single layer diamond – diamane, a two-dimensional (2D) form of diamond with a bilayer sp3 carbon nanostructure, has been initially predicted in 2009, while its experimental synthesis has only ...been reported very recently. This work carries out a comprehensive study on the vibrational properties of diamane nanoribbon (DNR) targeting the ultra-sensitive sensing applications. Based on in silico studies, it is found that the DNR resonator possesses a higher natural frequency and a large quality factor (Q-factor) on the order of 105 higher than those of a bilayer nanoribbon resonator. Under pre-tensile strain, the natural frequency of the DNR resonator receives a remarkable increase and its Q-factor maintains a high magnitude yielding to an extremely high figure of merit on the order of 1015. It is further found that the randomly distributed surface hydrogenation exerts negligible influence on the vibrational properties of the DNR resonator. However, an unevenly distributed hydrogenation results in out-of-plane deformation and significantly changes its vibrational properties. It is additionally found that the stacking configuration of the diamane leads to negligible influence on its vibrational properties. This study reveals that the DNR resonator has excellent vibrational properties, which are promising for the construction of ultra-sensitive resonator-based sensors.
The single layer diamond – based mechanical resonator shows excellent properties compared with other 2D materials-based resonator. Display omitted
Polymer nanocomposites with excellent mechanical performances have been increasingly sought after in engineering applications such as biotechnology, aerospace, and automotive areas. Through molecular ...dynamics (MD) simulation, this work systematically assessed the tensile performance of poly(methyl methacrylate) (PMMA) nanocomposite reinforced by randomly dispersed two-dimensional diamond-diamane. It is found that randomly dispersed diamane effectively enhances the tensile properties of PMMA with surface functionalization, and the enhancement effect can be remarkably augmented by cross-linking. Simulations reveal that the enhancement effect can be effectively tailored by the alignment of the diamane fillers. The PMMA nanocomposites exhibit much better tensile performance when the diamane fillers are uniformly aligned along the in-plane direction of the filler. Additional investigations show that larger diamane filler is preferred without cross-linking, while smaller diamane filler should be considered when cross-linking is present. Overall, the impacts of different factors on the tensile properties of PMMA nanocomposites are analysed in-depth in this work, which provides atomistic insights for the preparation of polymer nanocomposites with desired mechanical properties.
Effective enhancement on the tensile properties of polymer nanocomposites can be achieved by 2D diamond nanofiller. Display omitted
Viscosity stands as a pivotal property within asphalt binder, exerting influence not only over the pavement quality and construction efficiency but also over energy consumption and harmful gas ...emissions. Lower viscosity at the mixing temperature can reduce the energy consumption and emissions remarkably. As such, extensive efforts have been devoted to tailor the viscosity of asphalt by adding nanomaterials. Through atomistic simulations, this work provides an in-depth assessment on the viscosity of asphalt binder modified by ultrathin diamond nanothread (DNT). It is observed that the addition of DNT can reduce the viscosity of asphalt, a phenomenon traced back to the sp3-bonded nature of DNT that prevents the formation of π - π bonds with asphaltene molecules. Notably, samples endowed with higher count of stacked asphaltene molecules tend to display higher viscosity. Further investigation reveals that the sample with aggregated DNTs exhibits a lower viscosity, as the aggregated DNTs exert a more subdued influence on asphalt molecule mobility. Specifically, DNTs are found to promote the mobility of all molecules, and a remarkable enhancement on the mobility of saturated molecules is observed. This distinct behavior sets them apart from single-walled carbon nanotubes (SWNTs), where viscosity rises with increasing content due to the SWNT-induced aggregation of asphaltene molecules. Overall, this work unveils the intricate mechanisms influencing the viscosity of asphalt binders through diamond nanostructures. These findings could be beneficial for the design of asphalt binders with tailored rheological properties.
Ultra-thin diamond nanothread suppresses asphalt viscosity by reducing the π-π bonds and stacked asphaltene molecules within the matrix. Display omitted
•Atomistic simulations were carried out to assess the viscosity of asphalt binder.•Diamond nanothread (DNT) triggers a reduction in asphalt viscosity.•Higher count of stacked asphaltene molecules tend to result in higher viscosity.•DNTs promote the mobility of all asphalt molecules.
To facilitate the biomedical applications of biocomposites, researchers have used different types of fillers to enhance their mechanical properties. However, the addition of fillers not only changes ...the mechanical performance of the biocomposites, but also affects their printability, that is, their rheological properties. With the aid of atomistic simulations, this work investigates the influence of graphene size and aggregation on the rheological properties of polycaprolactone (PCL) composites. For the same weight ratio, increasing the graphene size causes the viscosity of the PCL composite to increase until a threshold edge length equal to PCL's average radius of gyration. After this threshold value, the viscosity decreases with increasing edge length. The PCL composite with multilayered graphene exhibits a lower viscosity compared with its counterpart with monolayer graphene. Specifically, the addition of graphene is shown to augment the shear‐thinning effect. The findings in this work provide a fundamental understanding of the rheological property of PCL composites with the addition of 2D nanofillers, which shed light on the ink design for bioprinting.
The viscosity of graphene/PCL composites is influenced by the graphene nanosheet (GN) size. The composite viscosity increases with the increase of graphene size until a threshold value, equal to the average radius of gyration of PCL chains, is reached. Further increase in the graphene size can reduce the composite viscosity. The viscosity is also influenced by the stacking of GNs.
Polycaprolactone Biocomposite Ink
The ink viscosity is a crucial factor in controlling the quality of the printed structure in 3D printing. By atomistic simulations, the geometric effect of graphene ...reinforcement on the viscosity of polycaprolactone biocomposite ink has been identified in article 2100507 by Haifei Zhan, Yuantong Gu, and colleagues. The relative size between the reinforcement and the radius of gyration of polycaprolactone chains determines the changing trend of the composite viscosity.
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