STRUCTURAL CHARACTERIZATION OF POLYMACROMONOMER IN SOLUTION BY SMALL-ANGLE X-RAY-SCATTERING

The polymerization of macromonomers provides polymers of extremely hig h branching density with regular branch length, branching number and b ranching interval. The intrinsic shape and size of these polymacromono mers were evaluated by small-angle X-ray scattering. The conformation of the backbone and side-chains was discussed. An oblate ellipsoid of revolution was proposed as an approximate shape of the polymacromonome rs at a low degree of polymerization by scattering profile fitting. An elliptical cylinder was found to outline the polymacromonomer in solu tion at larger degrees of polymerization. The 3D molecular model of a polymacromonomer with a low degree of polymerization (DPM = 7) suggest ed a random coil conformation for the backbone and side-chains. The co nformational change of the backbone chain is speculated to take place when the total degree of polymerization exceeds a certain limiting val ue, where the polymacromonomer is represented by a molecular bottle br ush as seen by light-scattering measurements.