We report on a new strategy for fabricating well-defined POSS-based polymeric materials with and without solvent by frontal polymerization (FP) at ambient pressure. First, we functionalize polyhedral oligomeric silsesquioxane (POSS) with isophorone diisocyanate (IPDI). With these functionalized POSS-containing isocyanate groups, POSS can be easily incorporated into a poly(N-methylolacrylamide) (PNMA) matrix via FP in situ. Constant velocity FP is observed without significant bulk polymerization. The morphology and thermal properties of POSS-based hybrid polymers prepared via FP are comparatively investigated on the basis of scanning electronic microscopy (SEM) and thermogravimetric analysis (TGA). Results show that the as-prepared POSS-based polymeric materials exhibit a higher glass transition temperature than that of pure PNMA, ascribing to modified POSS well-dispersed in these hybrid polymers. Also, the products with different microstructures display different thermal properties. The pure PNMA exhibits a featureless morphology, whereas a hierarchical morphology is obtained for the POSS-based polymeric materials. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1136-1147, 2009