You need to analyze inorganic nanoparticles, with a material in
the center (core) that is different from the material on the
outside (shell). In crystalline nanoparticles, the bond between
core and shell is usually strong due to which is not feasible to
separate them mechanically. Core-shell nanoparticles can be made
with variety of shapes (for simplicity in the image given as an
example only a spherical core-shell NP is shown). Consider that
both the core and the shell can be made up of more than one
element, the composition of each layer is not necessarily binary (a
metal and a non-metal), but some (or both) of them may have a
ternary, or even quaternary composition (i.e. be composed of up to
two different metals and two non-metals). You can assume that all
nanoparticles have the same composition (even if they have
different shapes and sizes), and that they only decompose at
temperatures higher than 400–600 ºC. The organic stabilizer used
for these nanoparticles is an amphipathic molecule, it adheres to
the surface inorganic with a polar functional group that has high
affinity for the atoms on the surface of the nanoparticle. The
stabilizer has a hydrophobic "tail" that can be aliphatic or
aromatic and can even contain heteroatoms (e.g. N, S) but has no
information about their a priori composition. The "tail" makes
these NP are dispersible in non-polar solvents. You can assume that
the stabilizer molecule would be a solid a room temperature, and
that you can separate it from the nanoparticles (if required for
analysis)
You can assume that the organic stabilizer is heat labile, and
that it decomposes below 300 ºC in an atmosphere of air, or below
350 ºC in an inert atmosphere. Based on all the information above,
answer the following questions.
a) What instrumental techniques would you use to identify the
substance that forms the organic coating, and to find which
functional groups make it adhere to the surface of the
nanomaterial?
b) You suspect that these particles may be quantum dots, and
therefore have a particular response to light UV. What instrumental
techniques would you use to investigate this possibility?
