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

When , the former equation can be simplified to the so-called Rayleigh-Gans-Debye
relation:
Actually, ΔR cannot be experimentally measured since I0 and r are unknown during the
experiment. However, in a routine experiment ΔR is determined from the experimentally
measured scattered intensities of the solution, Isolution, and a reference substance, Iref (usually
benzene or toluene) (23) which enables the derivation of their respective Rayleigh ratios.
Hence, the following equation can be derived providing a relation between the molecular
weight, Mw, of the particle considered and the second virial coefficient, A2 (29)-(30):
where
,
and
2.17
2.18
2.19
. I, Is and Iref, are
the experimentally measured scattered intensities of the solution, solvent, and reference,
respectively. For small particles at dilute concentrations equation 2.19 can be reduced to:
On the other hand, for large scattering particles the scattered intensity is no longer
independent of the scattering angle. The scattering vector q, which is experimentally
determined by the scattering angle and the laser light wavelength, , provides a quantitative
measure of the length scale of the static light scattering experiment, given by:
For very dilute solutions, interference between different scattering particles, the so-called
2.20
2.21
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