AGGREGATION KINETICS AND PRECIPITATION PHENOMENA IN POLY(PHENYLISOCYANIDE)

The preparation of N-phenyl-substituted poly(isocyanide) (N-phi-PIM) u tilizing a Ni(II) catalyst in methanol yields a brown material having a number average molecular weight of about 2000. Analysis of this ''as prepared'' polymer indicates that a rigid rod structure is present in the derived solid. Dissolution of this ''as prepared'' N-phi-PIM in h alocarbon solvents or THF apparently leads to unraveling of the helica l polymer with subsequent aggregation and precipitation of materials t hat have different properties from the original. These processes have been investigated by NMR, GPC, and light-scattering techniques in THF and other solvents. UV spectroscopy has been utilized to follow the ki netics of the aggregation process in solution. X-ray diffraction (XRD) measurements have been employed to investigate the changes attendant with precipitation. An explanation of these observations is offered th at implicates the uncoiling of the rigid rod helix as the most importa nt step in defining subsequent physical and chemical properties of the ultimate amorphous polymer. (C) 1997 John Wiley & Sons, Inc.