Unit 3 – The Chemistry of Engineering Materials Engineered Nanomaterials Flashcards
italicize
__________has attractive properties and amazing technological possibilities, which can be any one of the four basic types - metals, ceramics, polymers or composites.
nanomaterials
four basic types of nanomaterials
metals
ceramics
polymers
composites
fill in the blanks
The first – and broadest – definition of nanomaterials states that, these are materials where the sizes of the individual building blocks are less than _________ (a very small scale), at
least in one dimension (nm; equivalent to the diameter of approximately 500 atoms).
100 nm
The main difference between nanotechnology and conventional technologies is that the “bottom-up” approach is favored in _____________, whereas ____________
generally use the “top-down” approach.
nanotechnology
conventional technologies
nanotechnology uses what approach
bottom-up approach
conventional technologies use what approach
top-down approach
the expression _________ means starting from large pieces of material and producing the expected structure by mechanical or chemical methods.
top-down
__________ are produced via top-down processes, starting from bulk materials. The intended product is obtained by the application of mechanical and/or
chemical processes
Conventional goods
in “_________” processes where atoms or molecules are
used as the building blocks to produce nanoparticles, nanotubes, or nanorods, or thin films
or layered structures.
bottom-up
The
_______
starting with atoms and molecules as the building blocks that produced particles, nanotubes or nanorods and these products are also characterized
by their dimensionality.
bottom-up process
one-dimensional nanoparticles
nanotubes and nanorods
zero-dimensional structure
nanoparticles and fullerenes
two-dimensional
nanoplates (graphenes)
The _____________ of the diffraction pattern indicates that the direction of the platelets was perpendicular to the faces of the platelet;
hexagonal symmetry
In the formation of nanorods and nanoplates, the influence of
___________ is to be considered.
surface energy
At the circumference of each layer, the bonds are not saturated. The ___________ (short lines) need additional energy; thus, there is a strong tendency to saturate these bonds.
dangling bonds
Italicize
is the most important compound in this context with an ideal composition of Al2SiO3(OH)4.
Imogolite
_____________ tubes with the ideal composition are very narrow, with internal diameters of 1 nm and external diameters of 2 nm.
Imogolite
Discussions about graphite and fullerenes as special modification of carbon is essential in order to understand _________________________.
carbon nanotubes
Structure of graphite:
Each layer consists of interconnected ____________ with one carbon atom at each vertex.
hexagon
Italicize
These single layers of graphite are known as __________, and because of its structure and bonding it is often denominated as an infinitely extended, two-dimensional aromatic compound.
graphene
In ___________), one observes single bonds only, as nitrogen as well as boron are both in their three valency state.
boron nitride (BN
In the sense that graphene is a two-dimensional aromatic compound, __________, which also exist in the case of BN, are three-dimensional aromatics.
fullerenes
they are consist of a
combination of hexagons and pentagons;
fullerenes
The most common fullerene, and the first to be identified consists of ____ carbon atoms, with the molecular structure comprising 12 pentagons and 20
hexagons.
C60
The fullerene with the least number of carbon which is identified (experimentally) is ___ while the smallest stable fullerene is ____.
C20
C36
Fullerenes also appear quite often in many layers; these
aggregates are known as “___________” or “____________.”
nested fullerenes
onion molecules
__________ are formed by wrapping graphene layers of limited size to form a tube.
Nanotubes
The formation of nanotubes is not limited to single graphene layers and, as for fullerenes, both “_____” and “_________” nanotubes may be observed.
multiwall
single-wall
The ______________ consist of a series of coiled graphene layers and can be described perfectly using
electron microscopy
multiwall nanotubes
Nanocarbons which are a class of recently discovered materials have innovative and exceptional properties and are currently being used in some ___________ technologies and
will certainly play an important role in future high-tech applications.
cutting-edge
Three nanocarbons that play role in future high-tech applications are ________________.
fullerenes, carbon nanotubes, and graphene
Italicized
The material composed of C60 molecules is known as ____________
buckminsterfullerene
short term for buckminsterfullerene
buckyball
Italicized
In the solid state, the C60 units form a crystalline structure and pack together in a face-
centered cubic array. This material is called ________,
fullerite
Some of these compounds involve atoms or groups of atoms that are enclosed within the cage of carbon atoms (and are termed _________________).
endohedral fullerenes
For other
compounds, atoms, ions, or clusters of atoms are attached to the outside of the fullerene shell
(______________).
exohedral fullerenes
Carbon nanotubes are another molecular form of carbon which has recently been discovered that has some unique and technologically promising properties. Its structure consists of a single sheet of graphite (i.e., graphene) that is rolled into a tube; the term __________________ is used to denote this structure.
single-walled carbon nanotube (SWCNT)
_______________ carbon nanotubes (MWCNTs) consisting of concentric cylinders also exist
Multiple-walled
_____________ are currently being used as reinforcements in polymer-matrix nanocomposites to improve not only mechanical strength, but also thermal and electrical
properties.
Bulk nanotubes
___________ as the newest member of the nanocarbons, is a single-atomic-layer of graphite, composed of hexagonally sp2 bonded carbon atoms
Graphene
Italicized
The first graphene material was produced by peeling apart a piece of graphite, layer by layer using
plastic adhesive tape until only a single layer of carbon remained
micromechanical exfoliation or the adhesive-tape method
