Novel water-swellable beads based on an acryloylated polyaspartamide

Spherical polymeric microparticles have been prepared by a reverse-phase su spension polymerization technique. The starting polymer was alpha,beta -pol y (N-2-hydroxyethyl)-DL-aspartamide (PHEA) partially functionalised with gl ycidylmethacrylate (GMA) in order to introduce reactive vinyl groups in the side chain. The PHEA-GMA copolymer obtained (PHG) was cross-linked in a mi xture of water/hexane-carbon tetrachloride in the presence of sorbitan trio leate (Span 85) as surfactant and ammonium persulfate/N,N,N',N'-tetramethyl ethylenediamine as initiator system. The reaction was also carried out in t he presence of N,N'dimethylacrylamide as comonomer or N,N'-ethylenebisacryl amide as a cross-linking agent. The beads obtained were characterized by Fo urier transformIR spectrophotometry, particle size distribution analysis an d scanning electron microscopy, which revealed their microporous structure. X-ray diffractometry and differential scanning calorimetry showed the amor phous state and the dependence of the glass-transition temperature on tile chemical structure of the samples prepared, respectively. Finally, in order to have information on the water affinity of the networks obtained, swelli ng measurements were performed. The water regain values and the high rate o f swelling demonstrate a remarkable ability of the samples investigated to entrap water molecules. The dependence of aqueous swelling on the degree of cross-linking and the chemical structure of the samples is also shown.