Application Note
Characterization Of Polymers Using Light Scattering Techniques
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•Application Note: Characterization Of Polymers Using Light Scattering Techniques
Light scattering techniques are widely used for the characterization of solutions of polymers and macromolecules.
Dynamic light scattering (also know as photon correlation spectroscopy (PCS) and quasi-elastic light scattering (QELS)) measures the time-dependent fluctuations in the intensity of scattered light that occurs because the particles are undergoing Brownian motion. The velocity of this Brownian motion is measured and is called the translational diffusion coefficient D. This diffusion coefficient can be converted into particle size using the Stokes-Einstein equation.
Polymers are used in a wide variety of applications due to their diversity of properties. The molecular structure, conformation and orientation of the polymer molecules can greatly affect the macroscopic properties of the material.
Random coil polymer molecules have open conformations. This results in low refractive index differences with the continuous phase and as a result they scatter very little light. For such weakly scattering samples, the intensity of scattering observed using conventional DLS instruments (i.e. 90° detection) may not be sufficient for successful sizing measurements to be performed.
SOURCE: Malvern Instruments
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•Application Note: Characterization Of Polymers Using Light Scattering Techniques
