Studies on Structure of Poly(.EPSILON.-L-lysine) Spherulite Grown from Solution

The influence of solvent on spherulitic crystallization of poly(ε-L-lysine) (ε-PL) was investigated. In the solution crystallization of ε-PL, structure and properties of ε-PL spherulite were remarkably affected by the kind of solvent. Using dimethylsulfoxide (DMSO) as a solvent, most spherulites were negative and a few positive spherulites were grown. The fibrillar entities in a negative spherulite, which was grown in DMSO, were simply radiating outward from the center of the spherulite. Using water as a solvent, a spherulite was comprised of fibrillar entities that were structured with regularly repeated rings of bright-and-dark pattern. This bright-and-dark pattern in the spherulite would be caused by twisted fibrillar entities which were extended outward from the center of the spherulite. Using the DMSO/water mixture as a solvent, the structure of spherulite was remarkably affected by water, and the melting point of spherulite was 176°C.