Condensation of oligo-4-hydroxybenzaldehyde with aniline, 2-chloroaniline, 2-aminophenol, 2-aminotoluene, 4-aminotoluene, and 4-nitroaniline gave the corresponding Schiff base oligomers (OFAP, OKAP, OHAP, OOAP, OTAP, and ONAP, respectively). The products were characterized by H-1 NMR, Fourier transform infrared, ultraviolet-visible, and elemental analyses. The number-average molecular weight, mass-average molecular weight, and polydispersity index (PDI) values of the Schiff base oligomers were determined. Thermogravimetric analysis was used to compare the thermal stability of the oligomers, which showed the Schiff base oligomers to be resistant to thermooxidative decomposition. Weight loss of 5% and 50% occurred at temperatures of 122 and 475 degreesC; for OFAP, at 118 and 453 degreesC; for OKAP, at 182 and 491 degreesC; for OHAP, at 150 and 452 degreesC; for OOAP, at 132 and 401 degreesC; for OTAP, and at 193 and 414 degreesC for ONAP. (C) 2004 Wiley Periodicals, Inc.