Anionic living polymerization of macromonomers: Preparation of a particle-like purging reagent and characterization of poly(macromonomer)s

A cross-linked polystyrene particle (Merrifield resin, R-C6H5) was reacted with benzoyl chloride in nitrobenzene to produce R-C6H4-COC6H5 having a benzophenone group, and the R-C6H5-COC6H5 was reacted with a sodium mirror in THF under 10−5 mmHg to produce R-C6H5-CO−C6H5Na+ containing a benzophenone sodium as a particle-like purging reagent (PPBNa). (4-vinylbenzyl)Polystyrene macromonomers (PSM4: Mn=4.62×103, Mw/Mn=1.03 and PSM7: Mn=7.10×103, Mw/Mn=1.02) were dried under 10−6 mmHg for more than 72 h, purified by a special procedure using the PPBNa, and then were living anionically polymerized by sec-BuLi in benzene or n-BuLi in tetrahydrofuran to produce the corresponding poly(PSM)n star polymers. The resultant star polymers were characterized by gel permeation chromatography equipped with low-angle laser light-scattering (GPC-LALLS), membrane osmometry (OSM), and light-scattering (LS). Anionic living polymerization of the PSM macromonomers was confirmed by the fact that the molecular weight of the poly(PSM)n increased and by the fact that the initiation efficiency was constant despite an increase in the polymer yields. Some solution properties and specific dimensions characteristic to the poly(PSM)n star polymers are discussed by comparing the GPC-LALLS, OSM, and LS results for those polymers with the results for linear polystyrenes.