Smart Thermomechanochemical Composite Materials Driven by Different Forms of Electromagnetic Radiation

BONGIOVANNI ABEL, SILVESTRE; RIVAROLA, CLAUDIA R.; CUELLO, EMMA ANTONIA; RIBERI, KEVIN; MOLINA, MARÍA A.; RIVERO, REBECA; BARBERO, CESAR A.; MARTINEZ, MARÍA V.; ACEVEDO, DIEGO F.; GRAMAGLIA, ROMINA

Journal of Composites Science

mdpi

Año: 2020 vol. 4 p. 2 - 21

Photo-thermo-mechanochemical (P-T-MCh) nanocomposites provide a mechanical and/orchemical output (MCh) in response to a photonic (P) input, with the thermal (T) flux being the couplingfactor. The nanocomposite combines a photon absorbing nanomaterial with a thermosensitivehydrogel matrix. Conjugated (absorbing in the near infrared (NIR, 750?850 nm) wavelengthrange) polymer (polyaniline, PANI) nanostructures are dispersed in cross-linked thermosensitive(poly(N-isopropylacrylamide), PNIPAM) hydrogel matrices, giving the nanocomposite P-T-MChproperties. Since PANI is a conductive polymer, electromagnetic radiation (ER) such as radiofrequency(30 kHz) and microwaves (2.4 GHz) could also be used as an input. The alternating electromagneticfield creates eddy currents in the PANI, which produces heat through the Joule effect. A new kind of?product? nanocomposite is then produced, where ER drives the mechanochemical properties of thematerial through thermal coupling (electromagnetic radiation thermomechanochemical, ER-T-MCh).Both optical absorption and conductivity of PANI depend on its oxidation and protonation state.Therefore, the ER-T-MCh materials are able to react to the surroundings properties (pH, redoxpotential) becoming a smart (electromagnetic radiation thermomechanochemical) (sER-T-MCh)material. The volume changes of the sER-T-MCh materials are reversible since the size and shapeis recovered by cooling. No noticeable damage was observed after several cycles. The mechanicalproperties of the composite materials can be set by changing the hydrogel matrix. Four methods ofmaterial fabrication are described.