Effect of Processing Parameters on the Size and Size Distribution of High Molecular Weight Atactic Poly(vinyl alcohol) Gel Particles Prepared by Water-in-Oil Emulsion Method Using High Pressure Homogenizer
To produce high molecular weight poly(vinyl alcohol) (PVA) particles with various sizes for biomedical applications such as embolic treatment and as matrices for drug delivery systems, vinyl acetate was bulk-polymerized using 2,2-azobis(2,4-dimethyl valeronitrile) and the corresponding atactic PVA (a-PVA) was obtained by the saponification of poly(vinyl acetate). Then a-PVA particles were prepared by a series of processes, forming fine water-in-oil (W/O) emulsions using a high pressure homogenizer, with precipitation in ethanol, freezing and thawing, and drying. The effects of the agitation speed of the homogenizer, homogenizing time, and the oil content on droplet size, droplet size distribution, and the morphologies of the solid particles were studied. The droplet sizes shifted to smaller values with increasing agitation speeds and with decreasing oil contents. In addition, novel ketoprofen-loaded a-PVA particles were obtained using the same method adopted for the preparation of the particles. The release behaviour of ketoprofen from a-PVA particles was examined by high performance liquid chromatography.