Surface and morphological characterization of poly[styrene-co-(Boc-p-aminostyrene)] microspheres

Poly[styrene-co-(Boc-p-aminostyrene)] microspheres were obtained by dispersion copolymerization of styrene (ST) and Boc-p-aminostyrene (Boc-AMST) monomers. The polymer microspheres obtained were soluble in chloroform. The copolymer composition was determined by NMR, average molecular weight and polydispersity by gel permeation chromatography. Copolymers with different co-monomer molar content were synthesized with molecular weights ranging from 40 000-125 000, and polydispersity indices ranging from 2.0-3.5. Particle size by Coulter-counter measurements and surface area analysis by BET method were performed; the mean diameter of the particles ranged from 0.7 to 1.2 mum, the surface area ranged from 1.2 to 5.7 m(2) (.) g(-1) and the mean pore dimension was around 100 Angstrom. By scanning electron microscopy it was verified that the particles were spherical with a homogeneous size distribution. The relative surface density of NH groups on the particle surface, determined b X-ray photoelectron spectroscopy, was between 2.62 (.) 10(15) and 1.48 (.) 10(16) gen atoms/cm(2); this value increased with increasing content of aminated comonomer in the monomeric feed. Particle-water interactions, investigated by differential scanning calorimetry measurements, suggest that the presence of NH-COOC(CH3)(3) groups increases the capacity of water adsorption by the microspheres.