Complexes of Poly[Sodium(Sulfamate/Carboxylate)Isoprene] ... 912.2. Static and Dynamic Light Scattering
Light scattering measurements were performed on an ALV/CGS- 3
compact goniometer system (ALVGmbH, Germany) equipped with an ALV-
5000/EPP multi tau digital correlator and a He-Ne laser operating at the
wavelength of 632.8 nm was used as a laser light source. The measurements
were taken fixed angle 90°. In static light scattering (SLS) the time-averaged
scattered intensity at a single angle is proportional to the weight-average
molecular weight of the species as proved by the Zimm or Guinier
approximations [8]. In Dynamic Light Scattering (DLS) [9] the intensity auto-
correlation functions 푔(^2 )(푡) analysed by the CONTIN algorithm yields the
characteristic relaxation rate 훤(푞) (with 푞 the scattered wave vector) from the
position of the maximum (휏(푞)) of the distribution function of relaxation times
(훤(푞)=
1
휏(푞)). In the case of diffusive modes the diffusion^ coefficient 퐷^ is
obtained (훤(푞)=퐷∙푞^2 ). The hydrodynamic radius (푅ℎ) is extracted from the
Stokes-Einstein equation (equation 1).
푅ℎ=
푘퐵푇
6 휋휂퐷^ (^1 )^where 휂 is the viscosity of the solvent, 푘퐵 is the Boltzmann constant and 푇 is
the absolute temperature. All the distributions were found to contain one single
population of diffusing species and the polydispersities were extracted by
cumulants analysis as 휇훤^22 where 휇 2 is the second cumulant and 훤 the relaxation
rate of the correlation function (first cumulant).
All samples were filtered by 0.45μm hydrophilic Teflon Millipore filters
in order to eliminate dust or large clusters and loaded into standard 1cm width
Helma quartz dust - free cells (this was done also for ζ-potential
measurements).
2.3. Electrophoretic Light Scattering
Zeta potential [10] measurements were performed on a ZetaPlus Analyzer
(Brookhaven Instruments Corporation) equipped with a 35 mW solid-state
laser, operating at 660 nm. The calculation was made by the Henry equation in
the Smoluchowski approximation. The reported 휁-values reported are averages
of 10 measurements taken at 173° angle.