The morphology of poly(4-phthalimide) (PPI) crystals was examined by using reaction-induced crystallization of oligomers during solution polymerization. Polymerizations of alkyl 4-aminophthalates such as 1-ethyl 4-aminophthalate (IEAP), 2-ethyl 4-aminophthalate, 1-hexyl 4-aminophthalate, and 2-hexyl 4-aminophthalate were carried out at 330°C in a mixture of isomers of dibenzyltoluene without stirring. Nanoscale PPI ribbons having smooth surface were formed by the polymerizations of these monomers. The ribbons prepared from IEAP at a concentration of 2.0% for 24 h were averagely 12 μm in length, 150 nm in width, and 8 nm in thickness, in which the molecular chains aligned along the long axis of the ribbon. The phase-separated oligomers were fully cyclized imide oligomers, and this is of great importance for the formation of the ribbon. The obtained ribbons possessed high crystallinity and exhibited excellent thermal stability.
ASJC Scopus subject areas
- Materials Chemistry