Sulfated nanocrystalline cellulose (CNC-SO₃H) has a wide range of applications and can be tailored to suit various needs. These materials can be processed into transparent, flexible films suitable for electronic applications. The electronic performance of a CNC-CNC-SO3…X film, where X represents the counterion, is primarily influenced by its aggregation structure, crystallite mobility, and the dissociation of SO₃…X. These factors, in turn, affect the film’s intrinsic electronic properties, including its dipole moment.In this study, several CNC films were prepared with and without additives, and their intrinsic electrical properties were analyzed using dielectric spectroscopy [1]. Additionally, far-infrared (THz) spectroscopy was employed as a tool to investigate water interactions with the CNC surface in the films. This approach aimed to provide insights into the role of tightly bound water on the cellulose surface, which is crucial for understanding CNC film formation and modification.Three types of films were examined: (1) unmodified CNC-SO₃H films, (2) CNC-SO₃ films incorporating various counterions such as diethanolamine, triethanolamine, and 3,3′-dipropylnitrile, and (3) CNC films modified with azetidinium salts (Figure 1). The azetidinium salts were synthesized using epichlorohydrin and a secondary amine, forming a ring-closed structure that can conjugate with the sulfate half-ester on the CNC surface (Figure 2). In addition to dielectric and THz spectroscopy, the CNC suspensions and films were characterized using titration and FTIR analysis.Through this multi-technique approach, we aim to deepen the understanding of how different functional groups and additives influence the dielectric properties and water interactions in CNC films. These insights contribute to the development of CNC-based materials for advanced electronic and nanotechnology applications.