Pulse-induced Critical Scattering PICS

Titkova, E. Prokopova, B. Sedlaiek, V. Petrus, K. Dusek, and M. Bohdancky, European Polymer J., 1978,14,145. 

The method has been used to show that phase separation in poly(phenylene oxide)-toluene occurs by crystallization (see Chapter 12) of the polymer rather than by liquid-liquid phase separation, and to follow the kinetics of the process Kleintjens et al. have used PICS to obtain spinodals for branched polymer solutions. Koningsveld and Kleintjens have used it widely to study phase separation in polymer mixtures. 

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Experimental measurements of the spinodal curve require bridging of the metastable region of the miscibility gap, i.e. traversing this region without phase separation. A nice technique developed for this purpose is the Pulse Induced Critical Scattering (PICS) [64]. 

To improve the accuracy and reliability of the extrapolation procedure A HaLo anGreat Britain) (Gordon et al., 1974, 1975). The method itself was named pulse-induced critical scattering (PICS) (l)erhain et al., 1974 Gordon et al., 1974, 1975 Kennedy el al., 1975). 

Derham K., Goldsbrough J., Gordon M., (1974) Pulse-induced critical scattering (PICS) from polymer solutions, PureAppl. Chem. 38,97. 

Traditionally, turbidity or opacity has been used for detecting the cloud-point curve (CPC), which approximated the bimodal of the phase diagram. Evolution of this approach involved application of laser light scattering, which combined with small specimen size and precise temperature control led to the pulse-induced critical scattering (PICS) for spinodal determination. Unfortunately, the method is limited to the size of heterogeneity > 100 nm and the difference in refractive index of the two phases > 0.01. ° i... 

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