SMALL ANGLE NEUTRON SCATTERING STUDIES OF PRASEODYMIUM-CMPO POLYMERIZATION H

Abstract

Octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (OφD(iB)CMPO) and extracted praseodymium form large elongated polymers whose sizes and shapes were measured by small-angle neutron scattering (SANS). The particles were 17-40 Ȧ in diameter and up to 500 Ȧ long. The polymers are produced at low 0φD(iB)CMPO/Pr ratios, and their sizes decrease as OφD(iB)CMPO/Pr ratio increases. A model for the polymers that invokes bridging of successive praseodymium atoms by the two functional groups of 0φD(iB)CMP0 is supported by: (a) the formation of polymers by two other Afunctional extractants, whereas a comparable monofunctional extractant fails to form polymers, and (b) the long and thin shape of most of the observed polymers, exhibiting a radial extension that is consistent with the model. Four comparable carbamoyl-alkyl-phosphoryl extractants have been examined by SANS for their capacity to form polymers with praseodymium in C₆D₆. Consistent with the model, the extractants, having the more basic amidic carbonyl moiety form polymers; one with less a basic carbonyl group does not form a polymer,