2-COMPONENT GELATORS AND NUCLEATING-AGENTS FOR POLYPROPYLENE BASED UPON SUPRAMOLECULAR ASSEMBLY

The supramolecular assembly of octyl-, hexadecyl-, and benzyl substitu ted complementary tectonics based upon barbiturates (BA) and 2,4, 6-tr iaminopyrimidines (TP) were studied in bulk, in cyclohexane, and in a polypropylene matrix. As evidenced by means of wide-angle X-ray scatte ring, FTIR spectroscopy; and atomic force microscopy (AFM), BA/TP asse mbly led to the formation of nanofibrillated superstructures, whereas the individual BA and TP components exhibited layered superstructures. Nanostructure formation resulting from BA/TP assembly in polypropylen e melt accounted for nucleation of polypropylene crystallization, espe cially when using benzyl-substituted BA and TP derivatives instead of the corresponding n-alkyl-substituted derivatives. As a function of th e benzyl ring substitution pattern it was possible to vary interlayer spacing and to influence nucleation with optimum nucleation efficiency observed for 1.61 nm spacing in the case of MeBz-BA/Bz-TP. Injection molding in the presence of MeBz-BA/Bz-TP and of Bz-BA/MeBz-TP assembli es revealed increased stiffness, as determined by Young's modulus, wit hout sacrificing impact strength when the content of nucleating assemb ly was increased from 0 to 2 wt %. Transcrystallization of polypropyle ne onto BA/TP nanostructures was imaged by means of crossed-polarized light microscopy.