Poly(vinyl alcohol) was modified by an aldehyde acetal reaction with 2,4,6-trinitrophenylacetaldehyde to give a new energetic polymer poly(vinyl 2,4,6-trinitrophenylacetal) (PVTNP). The structure of PVTNP was characterized by elemental analysis, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectra. The glass-transition temperature of PVTNP was evaluated by differential scanning calorimetry (DSC), and the thermal stability of PVTNP was tested by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). DSC traces showed that the PVTNP polymer had one single glass-transition temperature at 105.3 degrees C. DTA and TGA curves showed that the thermooxidative degradation of PVTNP in air was a three-step reaction, and the percentage of degraded PVTNP reached nearly 100% at 650 degrees C. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 1643-1648, 2011