Influence of iota-carrageenan on the morphology and electrical properties of poly(ortho-phenylenediamine) based copolymers

A series of poly(ortho-phenylenediamine-co-aniline)/iota-carrageenan biocomposites were synthesized via oxidative polymerization. Infrared spectroscopy revealed the ionic interaction between the sulfate groups in iotacarrageenan (i-CRG) and the quaternary amine groups in the copolymer, demonstrating that i-CRG exerts the function as the dopant. Cyclic voltammetry showed redox potentials around 35 mV, indicating that the i-CRG presence does not constrain electroactivity. Additionally, the biocomposites presented ionic and electrical conductivity (in the range of 10(-5)-10(-3) S cm(-1)) determined respectively by electrochemical impedance spectroscopy and the four-point technique. Interestingly, it was observed by scanning electron microscopy that i-CRG played the role as a template since its presence, depending on the weight ratio respecting the copolymer, caused copolymer morphology modification. This set of properties is highly advantageous due to the combination of conduction mechanisms and electroactive behavior, which can be used in applications related to energy storage devices such as supercapacitors and chemical sensors.