Prof. Dr. Axel Müller

We present a facile access route to hydroxyl-functional narrow disperse microspheres of well-defined grafting density. Ethylene oxide has been grafted from highly crosslinked poly(divinyl benzene) microspheres by anionic ring opening polymerization using sec-butyllithium as initiator together with the phosphazene base t-BuP₄. Initially, core microspheres have been prepared by precipitation polymerization utilizing divinyl benzene (DVB, 80 wt.-%). The grafting of poly(ethylene oxide) from the surface resulted in the formation of functional core-shell microspheres with hydroxy-terminal end groups. The number average particle diameter of the grafted microspheres was 3.6 µm and the particle weight increased by 5.7%. The microspheres were characterized by SEM, FT-IR spectroscopy, elemental analysis and fluorescence microscopy. The surface grafting density (determined via two methods) was 1.39 ±0.06 and 1.76 ±0.08 chains·nm^-2, respectively.