Hidekazu Yoshizawa

Preparation of monodispersed polymeric microspheres for toner particles by the shirasu porous glass membrane emulsification technique

This investigation describes the experiment directed toward the production of monodispersed toner particles by suspension polymerization. That is, relatively monodispersed poly(styrene-co-divinylbenzene) microspheres containing electrifying additives were successfully prepared by suspension polymerization employing the Shirasu Porous Glass (SPG) membrane emulsification technique. The diameter distribution of the dispersed droplets prepared with an SPG membrane module was fairly narrow, compared with that prepared with a conventional mechanical homogenizer. The effect of Sumiplast Blue S as coloring matter and E-81 as charge control agent on the triboelectric discharging properties of prepared polymeric microspheres was studied. The addition of electrifying additives strongly affected the triboelectric discharging property. It was consequently clarified that a small amount of electrifying additives added raised the electrostatic capacity of polymeric microspheres. However, a further addition reduced the triboelectric discharge of polymeric microspheres.

Design and testing of a new cisplatin form using a base material by combining poly-D,L-lactic acid and polyethylene glycol acid against peritoneal metastasis.

Microspheres containing cisplatin (CDDP) embedded in poly‐d,l‐lactic acid (PLA) and polyethylene glycol acid (CDDP‐PPMS) were developed to improve treatment of malignant effusions. In vitro studies demonstrated that CDDP was released continuously for more than 4 weeks from CDDP‐PPMS without initial burst. CDDP‐PPMS was compared with CDDP aqueous solution (CDDP‐SOL) by i.p. administration in rats for 1) tissue distribution, 2) toxicity and 3) therapeutic effects against Yoshida sarcoma. We found that the CDDP concentration in the omentum was maintained at a higher level than in the CDDP‐SOL group, while the particles of CDDP‐PPMS were observed in the stomata of the omentum by electron microscopy. Concentrations of CDDP in the lung, liver, kidney and blood were lower in the CDDP‐PPMS group than in the CDDP‐SOL group. All rats given CDDP‐PPMS containing ≤28 mg/kg were alive, whereas in the CDDP‐SOL group, all rats given ≥16 mg/kg died from side effects. The LD50 of CDDP‐PPMS and CDDP‐SOL were 32.8 and 14.8 mg/kg, respectively. The survival of rats with peritoneal metastasis was better in the CDDP‐PPMS group than in the CDDP‐SOL group. Int. J. Cancer 76:709–712, 1998.© 1998 Wiley‐Liss, Inc.

STRIPPING RATE OF PROPIONIC ACID FROM STYRENE-DIVINYLBENZENE COPOLYMERIC MICROCAPSULES WITH TRI-W-OCTYL AMINE AS CORE MATERIAL

ABSTRACT The stripping rate of propionic acid from microcapsules containing tri-n-octyl amine was investigated using distilled water and aqueous NaOH as stripping solutions. The experiments were conducted at 303K. The stripping rate was found to be controlled by diffusion through porous microcapsule membrane and increased with an increase in the concentration of propionic acid in the microcapsules for each solution system. It was found that the stripping rates in aqueous NaOH solution system was higher than in distilled water at the same concentration of propionic acid in microcapsules. The experimental results in the NaOH solution system could be analyzed using a permeation model considering mass transfer accompanied by irreversible instantaneous neutralization reaction between NaOH and the propionic acid/tri-n-octyl amine complex in the microcapsule membrane.