Formation of Single‐Layered Double‐Hydroxide Platelets in Poly(vinylpyrrolidone) and Alginate Medium: Conductive, Capacitive, and Dielectric Properties of the Hybrid Films

Abstract

AbstractDirect synthesis from an adapted salt coprecipitation of single‐crystalline layered double‐hydroxide (LDH) platelets can be realized by using polyvinylpyrrolidone (PVP) assisted by an organo‐modifying agent, alginate (ALG). The formation of LDH inorganic platelets with a Zn/Al cation composition of 2:1 was demonstrated by TEM observations as well as by a topotactic restacking reaction that used the terephthalate molecule pillaring effect. From the perspective of PVP, LDH platelets can be viewed as hybrid filler. With regards to the inorganic platelets, the dispersive medium supplied by PVP chains in association with the biopolymer is an elegant process for generating single platelets, the whole of which can form an exfoliated polymer nanocomposite structure. The resulting transparent, crack‐free PVP films obtained from solvent casting were studied by electrochemical impedance spectroscopy (EIS) to evaluate their conductive, capacitive, and dielectric properties. Single LDH platelets have been found to be beneficial to the enhancement of the ionic conductivity, and values up to six orders of magnitude higher than PVP were reached for PVP LDH film that contains LiClO4 salt. In particular, a reversible behavior upon temperature cycling was observed for the latter in association with low activation energy. The linear Arrhenius‐type dependence of the conductivity was disrupted at 310 K, and this was also proven by the dielectric behavior expressed by the loss modulus M″(ω) as a function of the temperature as well as by an Argand diagram. Such an unexpected phenomenon is tentatively explained by a drastic change in the dielectric relaxation strength observed versus temperature. Such an easy, environmentally friendly, solvent‐free, and scalable one‐step synthesis to yield single platelets and ultimately polymer films bodes well for other chemical compositions in terms of hybrid assemblies as well as polymers.