Preparation of Divinylbenzene and Divinylbenzene-co-Glycidyl Methacrylate Particles by Photoinitiated Precipitation Polymerization in Different Solvent Mixtures

Highly cross-linked micrometer-sized polymer particles with intended use in liquid chromatography were made from divinylbenzene, alone or copolymerized with 2,3-epoxypropyl methacrylate, using photoinitiated precipitation polymerization. The polymerizations were made by irradiation from a 150 W short arc xenon lamp with 2,2′-azobis(2-methylpropionitrile) as initiator. A variety of solvents such as tetrahydrofuran (THF), toluene, 1-decanol, and 1-octadecanol were added to the polymerization mixture, singly or in combination with THF, in order to introduce and control the porosity of the particles. Polymerizations where cosolvents were used in combination with the near-Θ solvent acetonitrile resulted in a substantial increase in particle size. This made it possible to shorten the polymerization time while still obtaining particles in the desired size range of 2−5 μm. Scanning electron micrographs indicated that the particles prepared by addition of “good” cosolvents had what seemed to be a softer surface. The materials were packed into analytical columns at 60 MPa packing pressure and passed a pressure stability test up to 30 MPa pressure drop. Darcy’s law plots revealed that the columns had no tendencies for compression-induced back-pressure variations or bed collapse.