Self-Assembly of Synthetic and Biological Polymeric Systems of ...

where is the characteristic delay rate, which is related to the translational diffusion
coefficient, D, of a solute by means of the expression:
The diffusion coefficient is frequently used to determine the hydrodynamic radius, RH, of the
constituent particles by using the Stokes-Einstein equation:
where KB is the Boltzmann constant, T the absolute temperature and the liquid viscosity.
The hydrodynamic radius obtained by DLS represents an ideal hard sphere that diffuses with
the same speed as the particle under examination. Actually, particles are solvated and the
radius calculated from the particle diffusion corresponds to the size of the dynamic solvated
particle.
2.4.- Electron microscopy
Microscopy is an important tool for the characterization of nanomaterials structure. For
example, this set of imaging techniques may be used to examine the detailed shape, size and
distribution of a wide range of nanoscopic objects. There are different available classes of
microscopic techniques, such as the traditional optical microscopy, or more powerful ones
such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and
scanning probe microscopy (SPM), amongst others.
2.4.1.- Transmission electron microscopy (TEM)
Transmission electron microscopy (TEM) involves the transmission of an electron beam
through a sample in a high-vacuum environment. The images and their associated contrasts
arise from regional differences in electron densities in such sample. TEM has a resolution of ca.
1 to 100 nm and can provide very detailed structural information of polymeric materials. The
TEM specimens need to be very thin in order to enable the transmission of electron beams
through the sample.
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