On the relationship between synthesis parameters and morphology of the anionic polycaproamide obtained in organic media. III. Macroporous powders obtained using CO2 and carbodiimides as activating compounds

Abstract

The relationship between the type of activator and the morphology of polycaproamide (PCA) powders was investigated. The powders were prepared by anionic polymerization of caprolactam in ethylbenzene using sodium caprolactamate as initiator and CO2, diisopropylcarbodiimide, and dicyclohexylcarbodiimide as activators. The powders were characterized by optical and scanning electron microscopy, particle size distribution, extent of the specific area, porosity, pore size, and pore size distribution. The crystalline structure of PCA powders was also investigated using X-ray diffraction technique. Formation of PCA powders during phase separation is discussed. Powders morphology is simultaneously and competitively controlled by the rates of polymerization and phase separation processes. It seems that the determining factor in the obtainment of such macroporous powders is the stepwise manner in which the growing centers are formed in the reaction medium. In addition, the effect of the site where polymerization proceeds after the occurrence of phase separation on the ultimate morphology of the PCA powders is also discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 231–243, 1998