ATRP Grafting from Gel Coated Microspheres

Abstract

<p> Swellable microspheres prepared by the precipitation polymerisation of divinylbenzene-80 (DVB-80) and 2-hydroxyethyl methacrylate (HEMA), in a solvent mixture of methyl ethyl ketone (MEK) and heptane, were functionalised with 2bromopropionyl bromide, and 2-bromoisobutyryl bromide to prepare Atom Transfer Radical Polymerisation (ATRP) initiators. </p> <p> Methyl acrylate (MA) and methyl methacrylate (MMA) were grafted from the microspheres using CuBr and either 4,4'-dinonyl-2,2'-dipyridyl (dNbipy), or N,N,N',N",N"-pentamethyldiethylenetriamine (PMDET A) ligands. The morphology of the grafted microspheres was studied using electron microscopy (ESEM and TEM) and x-ray microspectroscopy. Adding equimolar sacrificial initiator resulted in improved control over the grafting and gave grafted and soluble polymer, with narrow polydispersity (PDI) and number average molecular weight (Mn) close to expected values. </p> <p> Base catalysed transesterification was used to cleave the grafted polymer. It was found that adding free initiator permits grafting from within lightly cross-linked gels to be carried out with good control over Mn and PDI. </p>