<p>Currently, multiwalled carbon nanotubes (MWCNTs) are finding applications in many scientific fields, such as materials science, physics, biology, and chemistry, some of which require these materials to be functionalized. Functionalization of MWCNT enables enhancement of their properties to achieve advantages for the development of innovative nanodevices. In the present work, a self-normalized photoacoustic technique was applied for measurement of the thermal diffusivity (TD) of nanocomposites formed from MWCNTs immersed in two different polymeric matrices: polyvinylidene fluoride (PVDF) and polyvinylpyrrolidone (PVP). Pristine carbon nanotubes (p-MWCNTs) were functionalized with two different solutions: HNO₃, and a mixture of HNO₃ and H₂SO₄. The nanocomposites were analyzed under different functionalization conditions. It was shown that the photoacoustic technique can detect differences in TD between these different nanocomposites.</p> Graphical abstract <p></p>