Inelastic neutron spectroscopy (INS) was used to investigate hydrogen atoms in local comb-like polymeric structures of PEI-C16 between 20 and 4000 cm -1 . Spectra were recorded at 20K to minimize the thermal motion of the adsorbed molecules and structure, using the inverse geometry time-of-flight spectrometer (TOSCA) at the ISIS Facility in the United Kingdom. 19 Data were reduced using the MANTID software package. Density Functional Theory (DFT) calculations were performed using Gaussian16 at the B3LYP/6-311G level of theory, in order to optimize the atomic positions of the comb-like polymeric structure idealized for PEI-C16-33%. Such optimized structure was then used in order to calculate harmonic vibrational frequencies associated with it. In order to compare derived theoretical spectra with the experimental INS measurements we needed to recalculate the intensity of its vibrational modes, using derived atomic displacements, which was done with the help of AbINS plugin within MANTID software.