Syntheses of Novel Polymer Micro-Spheres with Surface and Interior Grafts

Abstract

<p> Polymers and block copolymers have been grafted from hard and soft polymer micro-spheres by atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). The hard and soft micro-spheres were prepared by precipitation polymerization of divinylbenzene-80 (DVB80), and of DVB80/hydroxyethylmethacrylate (HEMA), respectively, in neat acetonitrile.</p> <p> Residual vinyl groups in the hard, poly(DVB80) micro-spheres were hydrochlorinated to form benzyl chloride groups that subsequently served as ATRP initiators for poly(styrene) and poly(styrene-block-4-methylstyrene) grafts. Hydrophilic poly(HEMA) and poly(2-( dimethylamino)ethyl methacrylate) poly(DMAEMA) were also grafted from hard micro-spheres containing bromopropionates, using ATRP in the presence of CuBr/Me4Cyclam.</p> <p> Hydroxy groups in soft, poly(DVB80-co-HEMA) micro-spheres were used directly as initiators for ring opening polymerization of ε-caprolactone catalyzed by aluminum compounds. In the addition, they were reacted with α-bromopropionyl bromide to form ATRP initiators.</p> <p> Several combinations of ATRP-ATRP and ROP-ATRP with different monomers were carried out using these initiator micro-spheres. In particular, the soft micro-spheres grafted with poly(methacrylic acid), poly(methylmethacrylate), poly(methylmethacrylate-block-dimethylaminoethylmethacrylate), poly(methylmethacrylate-block-trimethylammoniumethylmethacrylate), poly(methylmethacrylate-block-HEMA), poly(methylmethacrylate-block-glycidylmethacrylate), poly(ε-caprolactone-block- methylmethacrylate), poly(ε-caprolactone-block-dimethylaminoethylmethacrylate).</p> <p> The internal morphology of these homo and block copolymer grafted microspheres was studied using electron microscopy and x-ray microspectroscopy.</p>