Tailoring Electrical and Mechanical Properties of All-Natural Polymer Composites for Environmentally Friendlier Electronics

Here we report the effect of cellulose nanocrystal (CNC) addition on the structural, mechanical, and dielectric properties of ι-carrageenan nanocomposites. Free-standing nanocomposites with a CNC concentration up to 20 wt % were fabricated using solely water as a solvent by doctor-blade casting followed by room-temperature drying. CNC incorporation does not modify the structural and morphological features of neat ι-carrageenan films. Uniaxial tensile testing shows a marked increase in the Young’s modulus from 231 ± 24 MPa for neat ι-carrageenan to 1725 ± 50 MPa for the 5 wt % counterpart with no remarkable loss in ductility. Such an increase, which remains well above the theoretical prediction obtained from modified Halpin–Tsai equations, together with morphological observations, indicates that CNCs are homogeneously dispersed within the matrix, as well as the presence of a strong ι-carrageenan-CNC interface. Finally, it is observed that CNC incorporation enhances the real dielectric constant ε′ and the AC conductivity values thanks to the additional ι-carrageenan-CNC interfacial contributions to the dielectric response. Overall, the experimental results shown here provide approaches for the improvement of the mechanical and dielectric properties of polysaccharides from marine origin to increase their range of applications.