Bøger af E. Sélégny

The introduction to the first of these two volumes on Charged Gels and Membranes has recalled already that both were issued from the second Advanced Study Institute of Forges les Eaux, of which the co-directors were Professors G. E. Boyd and K. S. Spiegler. However, it seems necessary to add some further remarks for the eventual readers of this one volume only or for those of all four which now constitute the series. * One discovers that each volume is precisely linked to the next; and the total con­ tains a large number of the very fundamental steps by which macromolecular physical chemistry finds itself simultaneously at thefronNers of application and of biology. One often wonders how this is possible. Research has been the best means of unders~anding the microscopic elements oflife. Biomimetic phenomena or bioanalogue compounds in their turn have led to innumerable practical realisations. On one hand, the notion of 'vital force' receded and is disap­ pearing due to repetitive total and asymmetric synthesis* of always larger, and more complex, biological molecules. On the other hand discoveries of inter-relations in physical chemistry disengage the analogies between living and non-living systems: the interrelations between phenomena, between phenomena and structures or the appear­ ance of these structures under the influence of intermolecular forces or of gradients of more statistical forces.

The first four volumes of the series on 'Charged and Reactive Polymers' have been devoted to polymers in solution (Voh. I and II) or in gel and membrane forms (Vols. III and IV). In correlation with charges, other physical or chemical properties of macro- molecules have been considered. Understanding of charge and hydrophobic effects is equally important for synthetic and biopolymers or their systems. Optically Active Polymers are related to problems of the same class, since optical activity is an inherent property of both natural macromolecules as well as a great variety of polymers synthesized in the Jast twenty years. Optical activity is a physical spectral property of chiral matter caused by asymmetrical configurations, conformations and structures which have no plane and no center of symmetry and consequently have two mirror image enantiomeric forms of inverse optical rotation. The racemic mixture of chiral enantiomers is optically inactive. The most common form of optical activity was first measured at a constant wavelength by the angle of rotation of linearly polarized light. More recently the measurements have been extended to the entire range of visible and attainable ultraviolet regions where electronic transitions are observed, giving rise to the ORD technique (Optical Rotatory Dispersion). The Cotton effects appear in the region of optically active absorption bands; outside of these bands the plain curve spectrum is also dependent on all the electronic transitions of the chromophores.

Remark ably so, it is the difference in scale which characterizes the difference between poly electrolyte solutions and gels and membranes: the colloidal solution of macro molecules is heterogeneous only on the microscopic level, whereas the gel-solution system is a macroscopically heterogeneous one.