Hypothesis: Fabrication of polymeric nanocomposites with suitable nanomaterial via an in-situ polymerization approach results in multifunctional advanced materials. Experiments: The present work demonstrates the fabrication of interpenetrating polymer network (IPN)-based smart nanocomposites of polyurethane and polystyrene (PS) with different weight percentages of multi-walled carbon nanotubes (MWCNT). The MWCNT was grafted with pre-polymer of PS. The grafted-MWCNT and the nanocomposites were analyzed by Fourier transform infrared and Raman spectroscopic, X-ray diffraction, transmission electron microscopic studies. Further, different properties of the nanocomposites were evaluated. Findings: The fabricated nanocomposites showed excellent enhancement in mechanical (tensile strength: 175.9%; elongation at break: 161.9%; and toughness: 279.8%) and thermal (initial degradation temperature: 107.8%) properties compared to the pristine IPN. The improved properties are because of strong interfacial matrix-nanomaterial interactions. In addition, the nanocomposites demonstrated high water repellence (static contact angle varied from 127.9 degrees to 143.6 degrees), outstanding self-cleaning and anti icing (freezing delay time of 1850-2700 s) behaviors. Most interestingly, the fabricated nanocomposites exhibited excellent self-healing ability under the exposure of microwave (within 46-22 sat 300 W power input) and sunlight (within 318-257 s, light intensity: 0.9-1.1 x 10(5) lux). Therefore, the studied nanocomposites hold significant potential to be used in the domains of advanced smart materials. (C) 2019 Elsevier Inc. All rights reserved.