Physico-Chemistry of the Hydrolysed Polyacrylamide—Chromium III Interaction in Relation to Rheological Properties
This paper deals with the behaviour of hydrolyse d Polyacrylamide solutions in the presence of chromium III. First, using potentiometry and spectroscopy, we study the complexation between chromium III and sodium acetate used as a low molecular weight model for the polymer. Then the same methods are applied to investigate the polymer—Cr(III) complexation and the results are discussed in conjunction with the nature of the physical states of the systems. Finally, we perform rheological measurements in the sol—gel transition regime in a range where the number of crosslinking points can be calculated unambiguously.
Monomers and aggregates of Merocyanine 540 (MC540) in water are able to photoisomerize. The shape of the photoisomer absorption spectrum is very similar to that of the ground state. Triplet state of MC540 in water has been produced by energy transfer from triplet anthracene and displays a broad absorption spectrum between 600 and 700 nm. The triplet state may also be produced by direct excitation of MC540 with UV light. However, when the dye is excited by visible light, no triplet state absorbance in the red could be detected so that the triplet yield of MC540 in water seems to be excitation wavelength dependent.