3.3 - Organic Compound Ultra-Fine Particles

Abstract

This chapter presents the methods for making organic ultrafine particles (UFPs) via the gas evaporation method and describes the characteristics of these new materials. Organic UFP production was started by placing an organic compound in a crucible in the vacuum chamber. Although the mechanisms involved in this production process are not known in detail, the evaporated molecules collide repeatedly with inert gas atoms and with other organic molecules, thereby leading to coagulation and growth that yields UFPs. It was confirmed that organic UFPs can be made from a large number of organic compounds number using this method. Several examples are discussed in this chapter. The temperature of evaporation is low for organic compounds, so the resistance heating method is adequate. The shape and yield of the organic UFPs are sensitive to the structure of the crucible used, the substrate temperature, and the material used. The chapter describes the properties of organic UFPs. The main asset is the availability of submicron particles having a uniform size, which is difficult to achieve by any other means. The hydrophilicity and hydrophobicity of various UFPs formed by the gas evaporation method were examined. The significant increases in the affinity of organic compounds to various solvents by forming UFPs by the gas evaporation method can be used in many fields that are concerned with the dispersion of fine particles. The special surface effects and other characteristics of the UFPs can be used to advantage in devices and sensors.