Effect of Particle Size and Polarity of Long-Chain Molecules in Polymeric Films on the Supercooling Temperature

Abstract

We studied the effect of particle size and polarity of long-chain molecules on supercooling when dispersed in polymeric films. Supercooling of the molecules of greater than 20 °C, which plays a key role in the thermoreversible response of recording media, was not observed for the molecules alone but occurred only when the molecules formed particles dispersed in a polymer. As the size of particles grew from 0.1–1.0 μm to 3.5 μm, the degree of supercooling of behenic acid dispersed in a copolymer of vinyl chloride and vinyl acetate decreased from 30–40 °C to about 20 °C. The degree of supercooling also decreased from 21–41 °C to 8–17 °C as the polarity of the molecules decreased from fatty acids to fatty alcohols to alkanes. On the other hand, the degree of supercooling increased from 20 °C to 43 °C as the polarity of the polymer matrix increased. This large supercooling effect may be caused by the interaction between the molecules and the polymers which depends on the polarity of both the long-chain molecules and the polymers.