We disclose here that the distannoxane catalysts (2) exhibit a high reactivity in the ring-opening polymerization of /3-butyrolactone to afford poly [(R)-3-hydroxybutyrate] of high molecular weight (A/" > 100 000).

Introduction. A wide variety of microorganisms produce poly(3-hydroxybutyrate) (P(3HB)) as a carbon and energy supply.1 Recently, Imperial Chemical Industries (ICI) has developed a controlled fermentation process for the production of optically active copolyesters of (R)-3hydroxybutyrate and (R)-3-hydroxyvalerate (P(3HB-co-3HV), l).2 In these types of polyesters, the optically active 3HB 3HV1 CR)-3-hydroxyalkanoic acids play an important role in their biodegradability, biocompatibility, and other physical properties.1•3 However, this fermentation technique is expensive and inefficient. The synthesis of such high molecular weight polymers by ring opening of (R)or (S)-jS-butyrolactone has also shown to be costly,4 and the direct

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When rotational stirring was applied to an electrically neutral aqueous suspension containing negatively charged, monodispersed silica fine particles and a positively charged polyelectrolyte, monodispersed, spherical particles with a size of several hundred micrometers were obtained. Conditions such as the rotational stirring speed, solute concentration, and total suspension amount were examined to clarify the conditions under which the monodispersed, spherical particles can be obtained. Spherical particles with a uniform size were obtained because the solutes create aggregates by electrostatic interactions, and the flow of the suspension from rotational agitation disperses the aggregates. Additionally, the obtained monodispersed, spherical particles contained monodispersed silica fine particles in submicron size aggregates with short-range order. We found that monodispersed, spherical particles with a vivid structural color could be prepared by incorporating a small amount of a black substance in the spherical particles. Because monodispersed, spherical particles with various colors can be created using silica, polymer, and carbon, which are non-toxic materials, they may be useful as new, environmentally safe pigments.[a] M. Scheme 1. A schematic diagram of the method for preparing monodispersed particles by rotational stirring of an aqueous suspension containing monodispersed silica fine particles and PDDA.

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