Redox graft polymerization of vinylic monomers on ozone-activated poly(styrene-divinylbenzene) microspheres of narrow size distribution

Uniform micrometer-sized polystyrene/poly(styrene-divinylbenzene) composite particles were produced by a single-step swelling of polystyrene template microspheres with styrene, divinylbenzene and benzoyl peroxide, followed by polymerization of the monomers within the swollen particles at 70°C. Uniform crosslinked poly(styrene-divinylbenzene) microspheres of high surface area were then produced by dissolution of the polystyrene template part of the former composite particles. Hydroperoxide-conjugated microspheres were produced by ozonolysis of the crosslinked poly(styrene-divinylbenzene) particles. Redox graft polymerization of acrylonitrile and chloromethylstyrene on the hydroperoxide-conjugated particles was then accomplished. The influence of various polymerization parameters on the grafting yield was elucidated. Uniform polyaldehyde microspheres were produced from the former particles in two ways: (1) LiAlH₄ reduction of the nitrile groups of the polyacrylonitrile-grafted particles, followed by reaction of the formed primary amino groups with glutaraldehyde; (2) Sommelet reaction on the polychloromethylstyrene-grafted particles. Trypsin was then covalently bound to the polyaldehyde-grafted microspheres. A comparison between the enzymatic activity of the conjugated and free trypsin was accomplished.