IS CALORIMETRY A CRUCIAL TECHNIQUE FOR STUDYING INNOVATIVE NANOMATERIALS?

Abstract

It is well known that calorimetry is a powerful technique to determine the complete energetics of interaction processes. Unfortunately, over the years the calorimetry has been applied to restricted fields so that it has been underemployed in studying smart nanomaterials (polypseudorotaxanes, polymeric aggregates, surface functionalized nanoparticles, nanocomposites, etc.) to which a tremendous scientific interest has been recently addressed. Within this topic some relevant recent results from our laboratory will be described in the following. As concerns the supramolecular chemistry field, we exploited strategies to design stable and stimuli responsive polypseudorotaxanes based on cyclodextrins and homopolymers or block copolymers. This was done by modulating the structure of the polymer and tuning the macrocycles cavity size. The knowledge of the energetics of the cyclodextrin/polymer mixtures, determined from direct and accurate calorimetric measurements, provided not only straightforward insights to establish the stability of the complexes and the polymer phase behaviour, but also rigorous predictive tools to trigger and to control the release processes. We designed aqueous hybrid nanoclay-polymer structures that are inexpensive, biocompatible, environmental friendly and advanced for potential specific purposes. From calorimetry, the thermodynamics of the adsorption, which enabled us to interpret the behavior at the air/solution interface was determined. The nanoparticles functionalization was triggered by temperature and/or inorganic salts opening up to new routes for the synthesis of smart materials. Calorimetry and thermal analysis were revealed very efficient in studying nanocomposites based on nanoclay and biocompatible polymers. From all these studies one concludes that calorimetry plays a key role for the development of rather complex supramolecular machines and molecular devices.