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首页> 外文期刊>Journal of Microencapsulation: Microcapsules Liposomes Nanoparticles Microcells Microspheres >Air-filled polymeric microcapsules from emulsions containing different organic phases
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Air-filled polymeric microcapsules from emulsions containing different organic phases

机译：由含有不同有机相的乳液制成的充气聚合物微胶囊

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摘要

Air-filled polymeric microcapsules for use as a contrast agent in ultrasono-graphy have been prepared by the freeze-drying of different oil-in-water emulsions. The water phases consisted of a block copolymer in water. The organic phases consisted of a biodegradable polyester dissolved in (-)-cam-phene, cyclooctane, cyclohexane or tricyclene, which were relatively poor solvents for the polyester. A polymeric wall was, therefore, precipitated at the droplet surface early in the process, i.e. during freezing. Removing the solvent during freeze-drying, resulted in air-filled microcapsules. The microcapsules were suspended in saline after freeze-drying. All the suspensions contained echogenic microcapsules with a volume mean diameter of ~5—7 ~tm. Micro-scopic investigations showed that the microcapsules were spherical and hollow. Tricyclene and, to some degree, (-)-camphene were found unsuitable for industrial production due to melting points above 300C. Cyclooctane and cyclohexane were investigated as replacements for the initially chosen (-)-camphene, since they are liquids over a wider temperature range. These solvents gave improved yields, measured both as particle volume concentration per amount of polymer in suspension and acoustic attenuation at 3.5 MHz per amount of polymer in suspension, although the freeze-drying cycle was not optimized for these systems.
机译：通过冷冻干燥不同的水包油型乳剂，制备了在超声检查中用作造影剂的充气聚合物微胶囊。水相由在水中的嵌段共聚物组成。有机相由溶于（-）-cam-phene，环辛烷，环己烷或三环烷的可生物降解的聚酯组成，它们是聚酯相对较差的溶剂。因此，在该过程的早期，即在冷冻过程中，聚合物壁沉淀在液滴表面。冷冻干燥过程中除去溶剂，得到空气填充的微胶囊。冷冻干燥后，将微胶囊悬浮于盐水中。所有悬浮液均包含回声微胶囊，体积平均直径为〜5-7〜tm。显微研究表明，微胶囊是球形和空心的。由于熔点高于300℃，发现三环戊烷和某种程度上的（-）-樟脑不适合工业生产。对环辛烷和环己烷进行了研究，以替代最初选择的（-）-樟脑，因为它们在较宽的温度范围内均为液体。这些溶剂的收率提高了，以悬浮液中每份聚合物的颗粒体积浓度和悬浮液中每份聚合物的3.5 MHz声衰减来衡量，尽管这些系统的冻干循环并未优化。

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