Synthesis and characterization of poly(styrene/α-t-butoxy-ω-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 macromonomers (VB-polyGL). Macromonomers with number-average molecular weight (M) over bar (n) = 950 (VB-polyGL950) and (M) over bar (n) = 2700 (VB-polyGL2700) were used for these polymerizations, In all syntheses the initial concentrations of styrene and initiator (K2S2O8) were constant. The initial macromonomer-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 VB-polyGL2700, respectively. The diameters of microspheres obtained were smaller for the syntheses with higher concentrations of macromonomers. Syntheses 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 macromonomer. Their diameter distributions were monomodal, with a diameter polydispersity parameter (ratio of weight-average and number-average diameters) in the range 1.007 less than or equal to (D) over bar (w)/(D) over bar (n) less than or equal to 1.022. For each type of microsphere the fraction of polyGL in a surface layer and the surface concentration of sulfate anions were determined. The fraction of polyGL in the surface layer was related to the initial monomer composition in the polymerizing mixture. Adsorption of human serum albumin onto Surfaces of some poly(styrene/VB-polyGL) microspheres was up to 10 times lower than for the polystyrene microspheres obtained in a similar emulsifier-free emulsion polymerization of styrene.