Bulk photon correlation spectroscopy

Another largely unexplored area is the change of dynamics due to the influence of the surface. The dynamic behavior of a latex suspension as a model system for Brownian particles is determined by photon correlation spectroscopy in evanescent wave geometry [130] and reported to differ strongly from the bulk. Little information is available on surface motion and relaxation phenomena of polymers [10, 131]. The softening at the surface of polymer thin films is measured by a mechanical nano-indentation technique [132], where the applied force and the path during the penetration of a thin needle into the surface is carefully determined. Thus the structure, conformation and dynamics of polymer molecules at the free surface is still very much unexplored and only few specific examples have been reported in the literature. 

Patterson, G. D. Photon Correlation Spectroscopy of Bulk Polymers. Vol. 48, pp. 125-159. 

The use of photon correlation spectroscopy to study the dynamics of concentration fluctuations in polymer solutions and gels is now well established. In bulk polymers near the glass transition there will be slowly relaxing fluctuations in density and optical anisotropy which can also be studied by this technique. In this article we review the development of the field of photon correlation spectroscopy from bulk polymers. The theory of dynamic light scattering from pure liquids is presented and applied to polymers. The important experimented considerations involved in the collection and analysis of this type of data are discussed. Most of the article focuses on the dynamics of fluctuations near the glass transition in polymers. All the published work in this area is reviewed and the results are critically discussed. The current state of the field is summarized and many suggestions for further work are presented. 

We have examined all the published papers on the subject of PCS from bulk polymers. A clear picture has now emerged of the appropriate procedures to be followed in such studies. While only a few groups have made significant contributions to this area thus far, it is hoped that this review will stimulate new work. Photon correlation spectroscopy from bulk polymers is an especially promising field with exciting problems yet to be solved. Many of the key problems and suggestions for new work have been presented above. 

Figure 50. Temperature dependencies of the various relaxation times of OTP. Filled circles are a-relaxation times of bulk OTP obtained by photon correlation spectroscopy open diamonds are JG relaxation times obtained by dielectric spectroscopy open circles are the primitive relaxation times x0 of bulk OTP calculated by Eq. (10). The photon correlation spectroscopy relaxation times of OTP confined in 7.5-nm pores (A) 5.0-nm pores ( ) 2.5-nm pores ( ).

Patterson, G. D. Photon Correlation Spectroscopy of Bulk Polymers. Vol.48, pp. 125—159. Penczek, S., Kubisa, P. and Matyjaszewski, K. Cationic Ring-Opening Pdymerization of Heterocyclic Monomers. Vol. 37, pp. 1—149. 

Lee, H., Jamieson AM, Simha, R., Photon-correlation spectroscopy of atactic polystyrene in the bulk state near Tg, Journal of Macromolecular Science-Physics, B18, pp. 649-664 (1980). 

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