Synthesis and characterization of poly(styrene/alpha-t-butoxy-omega-vinylbenzyl-polyglycidol) microspheres

Polystyrene microspheres with polyglycidol (polyGL) in a surface layer were synthesized in batch radical emulsifier-free emulsion copolymerizations of styrene and surfmers, alpha -t-butoxy-omega -vinyl-benzyl-polyGL macromono mers (VB-polyGL). Macromonomers with number-average molecular weight (M) ov er bar (n) = 950 (VB-polyGL950) and (M) over bar (n) = 2700 (VB-polyGL2700) were used for these polymerizations, In all syntheses the initial concentr ations of styrene and initiator (K2S2O8) were constant. The initial macromo nomer-to-styrene ratios were varied from 1.10 X 10(-3) to 1.64 X 10(-2) mol /mol and from 3.46 X 10(-4) to 3.47 X 10(-3) mol/mol for VB-polyGL950 and V B-polyGL2700, respectively. The diameters of microspheres obtained were sma ller for the syntheses with higher concentrations of macromonomers. Synthes es with VB-polyGL950 yielded microspheres with number-average diameters ((D ) over bar (n)) from 216 to 900 nm and with a bimodal diameter distribution . The number-average diameters of microspheres obtained with VB-polyGL2700 varied from 220 to 650 mn, depending on the initial concentration of macrom onomer. Their diameter distributions were monomodal, with a diameter polydi spersity parameter (ratio of weight-average and number-average diameters) i n the range 1.007 less than or equal to (D) over bar (w)/(D) over bar (n) l ess than or equal to 1.022. For each type of microsphere the fraction of po lyGL in a surface layer and the surface concentration of sulfate anions wer e determined. The fraction of polyGL in the surface layer was related to th e initial monomer composition in the polymerizing mixture. Adsorption of hu man serum albumin onto Surfaces of some poly(styrene/VB-polyGL) microsphere s was up to 10 times lower than for the polystyrene microspheres obtained i n a similar emulsifier-free emulsion polymerization of styrene.