LAUSR

Abstract The ubiquitous behavior of thermoresponsive polymers (TRPs) in terms of their amphiphilicity and reversible behavior towards temperature make them to exhibit wide applications in biomedical science, biosensors and biotechnological fields. The electrical and surface properties of multiwalled carbon nanotubes (MWCNTs) have received immense attention due to their high flexibility to take any shape (tube, circles) to bind with different macromolecular moieties. Nonetheless, TRPs-MWCNTs interactions with variation in temperature are rarely explored. However, the low solubility of carbon nanotubes (CNTs) in molecular solvents limits their utility in biological process. Therefore, functionalization of CNTs was performed to enhance the dispersibility of CNTs in aqueous medium. In this present study, effect of functionalized carbon nanotubes (fCNTs) on the coil to globular conformation of poly (N-vinylcaprolactam) (PVCL) is explored. PVCL exhibits coil to globular transition due to its biocompatible nature with several additive in permissible range of temperature values. To investigate the lower critical solution temperature (LCST) of PVCL in presence of fCNTs, various biophysical techniques such as fluorescence spectroscopy, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) were employed. Furthermore, for better understanding of morphological changes of PVCL in fCNTs, Transmission electron microscopy (TEM) was assessed. The DSC and DLS results confirmed that LCST value of PVCL (32.0 °C) has dropped by 2 °C in presence of fCNTs due to hydrophobic interactions of polymer and fCNTs. This exclusive modification in LCST of PVCL will be sensitive in biological applications. We have studied the first time effect of fCNTs on the phase transition behavior of PVCL which will lead to its widespread applications in the field of biomedical sciences such as drug delivery systems.