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Forslag til Prosjektoppgaver, høsten 2018

Forslag til Masteroppgaver, våren 2019

TKT4540 - Nanoteknologi, fordypningsprosjekt TKT4930 - Nanoteknologi, masteroppgave

NTNU Nanomechanical Lab

www.ntnu.no/nml

Veileder:

Professor Jianying He

Professor Zhiliang Zhang

Group introduction:

NTNU Nanomechanical Lab (NML) was established in 2006 as part of the NTNU Nanotechnology.

Currently there are 2 permanent faculty members, Professor Zhiliang Zhang who is on sabbatical

leave at California Institute of Technology until June 2018, and Professor Jianying He, 17 PhD

students and 3 postdoc research fellows in the group. 5 of the PhD students are from MTNANO

program in addition to 1 from MTNANO already finished his PhD. In the past, NML has supervised 9

master students in Nanotechnology. In addition to other ongoing projects, Prof. Zhang and Prof. He

are both leading so-called FRINATEK (hard competition) projects financed by the Research Council

of Norway.

Our research focuses on both the fundamental understanding of the nanoscale mechanisms and applied

nanotechnology. The topics varied with nanostructured materials and surfaces for anti-icing, effective

CO2 condensation, thermal interfacial material enhanced heat transfer, nanoscale additive

manufacturing et al. Both atomistic simulations (density functional theory and molecular dynamics)

and synthetization, fabrication and characterization using NTNU NanoLab and NML.

Our recent research news:

Får problematisk is til å sprekke opp

Den brennende isens hemmeligheter

Our latest research paper appeared in the Nano Letters:

Grain-size Controlled Mechanical Properties of Polycrystalline Monolayer MoS2

List of topics:

Super-Dewetting Surfaces

Super-Low Ice Adhesion Surfaces

3D Printing of Nano-Architected Metals

Real-Time Molecular Dynamics Simulation for Nano-Engineering Energy Storage Materials

Discover CO2-phillic materials by Deep learning

Wetting on 2D single-layer molybdenum disulfide MoS2

Syntheses and Multiphysical Characterization of Ultra-thin Metal Film on Polymer Substrate

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Title Super-Dewetting Surfaces

Supervising team

Professor Zhiliang Zhang, zhiliang.zhang@ntnu.no Professor Jianying He, jianying.he@ntnu.no www.ntnu.no/nml

Background In the past decade we have witnessed a drastic increase in the understanding and applications of the so-called superhydrophobic surfaces. It is now well understood that a superhydrophobic surface with its ability to repel invading water—that is, to display a very large apparent contact angle (> 150° ) and a very small roll-off angle, can be created by combining the surface roughness with a hydrophobic material. Superhydrophobic surfaces find numerous applications, for example, in oil-water separation, drag reduction, stain repellency, self-cleaning, fog harvesting, micro fluidics and efficient dropwise CO2 condensation. However, the development of the state-of-the-art superhydrophobic surfaces has come across one bottleneck. Surface superhydrophobicity is attributed to the formation of the Cassie-Baxter wetting state where a water droplet contacts only the tips of the rough surface. The problem is that the designed Cassie-Baxter state is mostly metastable. The superhydrophobicity is remarkably fragile and can break down, due to the wetting of the surface texture to yield the Wenzel state under various environmental conditions, such as elevated pressure, high droplet impact and in particular vapor condensation. Due to large energetic barriers that impede the reverse transition (dewetting), this breakdown in superhydrophobicity has been widely believed to be irreversible. Recently, there is a clear indication that this limitation can be overcome by manipulating the 4 parameters shown in the following figure.

Illustration

© Copyright Zhiliang Zhang

Aims The project study will be a literature survey and develop an understanding of the scientific problem. The master study will design and fabricate super-dewetting surfaces, which enable spontaneous transition from Wenzel to Cassie-Baxter state by manipulating surface chemistry, topology and gradients. The topic has high breakthrough potential and great possibility for international journal publications.

Methods Mostly experimental and use the NTNU NanoLab

References Contact us

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Title Super-Low Ice Adhesion Surfaces

Supervising team

Professor Zhiliang Zhang, zhiliang.zhang@ntnu.no Professor Jianying He, jianying.he@ntnu.no www.ntnu.no/nml

Background Preventing icing on exposed surfaces is important for life and technology. While suppressing ice nucleation by surface structuring and local confinement is highly desirable and yet to be achieved, a realistic roadmap of icephobicity is to live with ice, but with lowest possible ice adhesion. Super-low-ice-adhesion (10 kPa) is defined as the adhesion where a cubic meter of ice can fall down by its own weight. Ice adhesion can be lowered by multiscale crack initiators, details see the reference. NTNU Nanomechanical Lab in the last years has created surfaces with ice adhesion as low as 5.7 kPa by introducing surface sub-structures. However, the surface sub-structures have not been optimized. The target is to reach the ice adhesion far below 1kPa.

Illustration Unique concept

© Copyright Zhiliang Zhang

potential application

Aims The project study will mainly focus on literature survey and get familiar with the established

procedures to create super-low ice adhesion surfaces. The master study will work on optimizing the surface sub-structures to reach the lowest possible ice adhesion, below 1kPa. The topic has potential to patent the optimized sub-structures for lowest possible ice adhesion surfaces.

Methods NTNU NanoLab will be used to synthesize the surface, lab at Department of Structural engineering will be used for ice adhesion testing.

References http://pubs.rsc.org/en/content/articlelanding/2017/sm/c7sm01511a#!divAbstract

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Title 3D Printing of Nano-Architected Metals

Supervising team

Professor Zhiliang Zhang, zhiliang.zhang@ntnu.no Professor Jianying He, jianying.he@ntnu.no www.ntnu.no/nml

Background

In 3-D printing—also known as additive manufacturing—an object is built layer by layer, allowing for the creation of structures that would be impossible to manufacture by conventional subtractive methods such as etching or milling. Additive Manufacturing (AM) is a revolutionary technology with possibility of 3D printing any material, any shape, any quantity and in any fields, without the need for specialized tooling. Today’s resolution of most commercially available metal AM processes is ~20–50 μm. However, thanks to a new technique developed at Caltech, for the first time, it is possible to create complex nanoscale metal structures using 3-D printing.

Illustration

Aims The purpose of the project study is to get familiar with the method established by the

Caltech group for Ni-based structures. The aim of the master study is to explore the possibilities to extend the method to other metals, such as cu or aluminium.

Methods Experimental study at the NTNU NanoLab

References https://www.nature.com/articles/s41467-018-03071-9

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Title Real-Time Molecular Dynamics Simulation for Nano-Engineering Energy Storage Materials

Supervising team

Professor Zhiliang Zhang, zhiliang.zhang@ntnu.no Professor Jianying He, jianying.he@ntnu.no www.ntnu.no/nml

Background

The common characteristics of the energy storage materials can be generalized as charging / discharging / recharging processes. To atomistically simulate the rate-controlling charging/dis-charging/recharging processes in energy storage materials is very challenging since these processes are slow on the scale of seconds, minutes or even longer. This is an essential limitation for the classical molecular dynamics (MD) simulations which is based on solving Newton’s equation of motion on the scale of thermal oscillations. The time increment for the classical MD simulations is about 0.5 to 2 femtoseconds (10-15 second) and the longest time period today any MD can simulate is around 100 nanoseconds (10-7 second). This limitation renders the classical MD inapplicable to slow kinetic processes. Recently a new method called diffusive molecular dynamics (DMD) which is able to atomistically simulate real time kinetic process (minutes or hours), has been developed by Prof. Michael Ortiz’s group at Caltech.

Illustration

© Copyright Zhiliang Zhang

Aims The project study will learn the classical molecular dynamics for simulating fast kinetics. The master study will employ the DMD to evaluate the performance of nano-engineered energy storage materials.

Methods Computational simulation using the LAMMPS code

References Contact us. We will cooperate with Prof. Michael Ortiz at Caltech.

Remarks If you are interested in programming and modeling, this is a good topic.

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Title Discover CO2-phillic materials by Deep learning Supervising team

Professor Jianying He, jianying.he@ntnu.no Professor Zhiliang Zhang, zhiliang.zhang@ntnu.no www.ntnu.no/nml

Background Designing CO2-philic materials is a key to industry-practical Carbon Capture and Storage (CCS) technologies. Given the extremely large number of possible CO2-philic chemical compounds, especially those organic functional groups, it is requisite to utilize the most powerful and accurate theoretical strategy to avoid the costly yet low-efficient trial-and-error first phase experimental material development. The current project aims to collect and create big data of accurate atomistic interactions and binding thermodynamics between CO2 and a great variety of organic functional groups at varied temperature and pressure, and further to construct predictive models of CO2-philicity using deep learning methods for identifying the universal CO2-philic determinants and to design materials CO2-philicity performances.

Illustration

Aims The project study will focus on literature review and learn to use atomic simulations to

generate the training data set. The master study will learn to construct the predictive models by applying the deep learning method for CO2-philicity.

Methods Atomistic simulations by LAMMPS code

References Contact us.

Remarks If you are interested in programming and modeling, this is a good topic.

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Title Wetting on 2D single-layer molybdenum disulfide MoS2 Supervising team

Professor Zhiliang Zhang, zhiliang.zhang@ntnu.no Professor Jianying He, jianying.he@ntnu.no www.ntnu.no/nml

Background

Two dimensional (2D) transition metal dichchalcogenide crystals, consisting of a transition metal layer sandwiched between two chalcogenide layers in a trigonal prismatic structure, have attracted huge amounts of attention in recent years because of their distinctive electrical, optical and mechanical characteristics. Single-layer molybdenum disulfide (MoS2), as the most representative 2D TMDCs, is a typical direct gap semiconductor with an intrinsic bandgap of about 1.8 eV due to quantum confinement. Also, single-layer MoS2 shows excellent intrinsic electronic mobility and high on-off ratios. Such a host of fascinating properties of single-layer MoS2 renders it great interesting both for fundamental studies of novel physical phenomena and for a wide range of applications in electronics systems, such as field-effect transistor, phototransistors, optoelectronics, nanoelectromechanical devices. One of the interesting physical properties is surface wetting. The wettability of graphene has been substantially investigated, however, the wetting of MoS2 structures has remained unexplored despite its great potentials in future applications.

Illustration

Aims The project study will study the structures and properties of MoS2.

The master study will study the interactions of the MoS2 with water.

Methods Both simulation and experimental work at NanoLab are possible, depending on the interest.

References https://pubs.acs.org/doi/10.1021/acs.nanolett.6b05066 https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.7b05433

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Title Syntheses and Multiphysical Characterization of Ultra-thin Metal Film on Polymer Substrate

Supervising team

Professor Jianying He, jianying.he@ntnu.no Professor Zhiliang Zhang, zhiliang.zhang@ntnu.no www.ntnu.no/nml

Background

Interfaces are everywhere in nature and engineering. Their properties are critical to a variety of processes and systems, ranging from thermal management of electronics, icing of solid surfaces to renewable energy applications. The intrinsic mechanisms that underlie interface properties are intertwined and inherently coupled with mechanical stresses. One extremely complex example, upon which this proposal is focused, is the heat conduction through metal and polymer interfaces with characteristic length scales ranged from a few nanometers to tens of micrometers. Due to the dissimilarity between metal and polymer, a major stress-coupled thermal resistance arises at the interface and impacts the functionality of the material system. Though the interface mechanical and thermal properties have been studied individually, the stress-coupled heat transfer is so far untouched either theoretically or experimentally. Thermal interface materials (TIM) have been first introduced in polymer composites, and accepted in electronic systems as the route for improving the interface thermal conduction between semiconductor chips and metal heat spreaders, heat pipes and heat sinks. In the project, we will for the first time bring TIMs to the metal and polymer interface to optimize the stress-coupled thermal properties. Nanostructured graphitic TIMs, such as carbon nanotube (CNT), graphene and their derivatives, are expected to significantly improve the paths of heat transfer within the interface and smooth the dissimilarities of metal and polymer. The project work is a part of FRINATEK Young Research Talent (YRT) project Engineering Metal-Polymer Interface for Enhanced Heat Transfer (HEFACE http://www.ntnu.edu/nml/heface).

Illustration

Aims The project will synthesize nanoscale polymer-metal bilayer structure and

characterize thermal-mechanical properties.

Methods Both simulation and experimental work at NanoLab or NTNU Nanomechanical Lab are possible, depending on the interest.

References http://www.ntnu.edu/nml/heface

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Title Nanoparticle-based magnetic superstructures for anti-icing applications

Supervising team

Professor Jianying He, jianying.he@ntnu.no Professor Zhiliang Zhang, zhiliang.zhang@ntnu.no PhD students Verner Hå konsen verner.hakonsen@ntnu.no www.ntnu.no/nml

Background

Superstructures comprising nanoscale building blocks have been shown to exhibit extraordinary properties not found elsewhere in nature, leading to its own class of materials referred to as metamaterials. We would like to investigate the potential of bottom-up fabricated nanoparticle-based magnetic superstructures in the field of anti-icing – icephobic materials. There are three aspects of anti-icing that a good icephobic material should be associated with: 1) Repel incoming (supercooled) water droplets – superhydrophobicity. (2) Delay ice nucleation in case water settles on the surface. (3) In case the water freezes on the surface the ice should be removed with the lowest possible ice adhesion. The aforementioned nanoscale superstructures might hold the key to overcome present problems encountered so far in the field of anti-icing, and will be the topic for further investigation.

Illustration

Aims There are several potential assignments in this field for project- and master's theses and

each assignment should be picked according to the candidate’s interests. Please come and discuss! Examples of project/master's assignments are:

Investigate the potential of nanoparticle-based magnetic superstructures as icephobic surfaces. This assignment is first and foremost experimental, with emphasis on the fabrication of superstructures which will be performed in NTNU NanoLab. The fabrication technique of choice would be magnetic field induced self-assembly, and characterization tools like S(T)EM and SEM Apreo could be used for visual inspection. Simple anti-icing experiments will be performed if time permits.

Investigate the link between mechanical properties and (nano)magnetic properties in nanoscale magnetic superstructures (nanocomposite systems). The fabrication of superstructures will be performed in NTNU NanoLab in a similar manner as the first example above. Important characterization tools here would be S(T)EM and FIB. Further characterization will, however, not be focused on anti-icing (indirectly related though) but mechanical characterization (nanoindentation), which will be performed in NTNU Nanomechanical Lab.

Methods Experimental work at NanoLab and NTNU Nanomechanical Lab.

Fig. 1 High-resolution cross-

sectional SEM image of self-

assembled magnetic superstructures.

Fig. 2 SEM image of self-

assembled monolayer of

nanocubes.

Fig. 3 SEM image showing

supercubes consisting of 10 nm

magnetic nanocubes.

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Title Characterization of Nanoscale Metal Coated Micron-Sized Polymer Sphere

Supervising team

Professor Jianying He, jianying.he@ntnu.no Professor II Helge Kristiansen, helge@conpart.no PhD candidate Molly Bazilchuk, molly@conpart.no www.ntnu.no/nml

Background

Conductive adhesives are integral in the assembly of electronic components such as LCD screens, solar cell modules and car electronics. Micron-sized polymer particles with nanoscale metal coatings (MPS) are an important component in conductive adhesives. Using the Ugelstad process, Conpart AS produces polymer particles in the size range of 3-30 µ m. The particles are further coated with a 30-300 nm thick layer of nickel, gold or silver, depending on the final application. Understanding the electrical, mechanical and thermal properties of these particles is critical to optimizing their function in application. At the NTNU Nanomechanical Lab, a unique electromechanical characterization technique has been developed. Single particles are compressed and their electrical resistance monitored as a function of compression. However, experiments so far have focused on particles in air, whereas the particles will be surrounded by a viscous adhesive in application. The coating roughness is a significant factor in the particle performance, and has not been studied in detail. In addition, the coating roughness will change due to plastic deformation as the particle is compressed, as is the case in many applications.

Illustration

Aims There are two projects in this field. Particles for testing will be provided by Conpart.

‒ Surface characterization of MPS. The project will be developing a repeatable experimental technique for characterizing the particle surface roughness. This can be further extended in combination with single particle compression tests to examine the plastic deformation of the coating roughness.

‒ Electromechanical measurements of MPS in viscous liquids. The goal of project is to characterize the electromechanical properties of metal-coated polymer particles in viscous liquids that simulate the properties of epoxy-based adhesives. Using electromechanical nanoindentation, a systematic investigation of the influence of adhesive viscosity, particle size, metallization, coating thickness, and polymer core should be performed.

Methods Experimental work at NanoLab and NTNU Nanomechanical Lab, such as atomic force microscopy (AFM) for surface roughness measurements, scanning electron microscopy (SEM) to image the particles, flat-punch electromechanical nanoindentation for individual particles, which is exclusively available to students at NTNU Nanomechanical Lab.

References https://aip.scitation.org/doi/full/10.1063/1.4954218 https://aip.scitation.org/doi/full/10.1063/1.4959783