The solubility parameters of multiwalled carbon nanotubes (CNTs) was tuned via their chemical modification with pyrrole compounds (PyCs), by means of a simple and sustainable methodology. PyCs were synthesized with high atom efficiency through the Paal–Knorr reaction of primary amines with 2,5-hexanedione, in the absence of solvents and catalysts. Methylamine, 1-dodecylamine, 2-amino-1,3-propanediol, and 3-(triethoxysilyl)propan-1-amine were selected. PyCs are characterized by two moieties, the pyrrole ring and the substituent of the nitrogen atom, and can be considered as Janus molecules. The functionalization of CNTs occurred with a high yield by simply heating CNTs and PyC. The whole reaction pathway did not produce any waste and was characterized by a carbon efficiency up to almost 100%. Thanks to the variety of PyC chemical structures, the CNT solubility parameter was modified in a pretty broad range of values, in the expected direction. Stable CNT dispersions were prepared in different solvents. From the aqueous dispersion, coating layers were prepared with high electrical conductivity, larger with respect to a top commercial product. The “pyrrole methodology” reported here is based on one reaction and allows almost infinite variations of the CNT solubility parameter, thus promoting their compatibility with target matrices and allowing the preparation of nanocomposite materials with improved properties. This work thus paves the way for a highly efficient exploitation of CNTs.

Abstract-In this paper, an algorithm for breathing rate extraction from PPG signal is proposed. Two critical aspects have been endorsed during the implementation: i) good performances and ii) low computational complexity. The proposed solution is based on the Empirical Mode Decomposition (EMD) approach and it proves to be robust and accurate even in presence of noisy epochs. It has been validated on two distinct datasets: a)experimental data we have collected using wearables for physiological monitoring and b) recording sessions from PhysioBank MIMIC II Waveform Database. The presented results showed a mean absolute error of 0.0044 Hz, corresponding to 0.26 breaths per minute.

A biosourced Janus molecule was used as a coupling agent between silica and unsaturated polymer chains in an elastomeric composite suitable for tire compounds with low energy dissipation, with potential important reduction of the environmental impact of the tire. 2-(2,5-Dimethyl-1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP) was synthesized through the neat reaction of serinol and 2,5-hexanedione, with a high atom efficiency (ca. 85%). Adducts of SP with silica were prepared (SP ≈ 9% by mass), with very high yield. In the whole process, from reagents to adducts, only substances from natural sources could be used, and the only co-product was water and the carbon efficiency was close to 100%. The silica/SP adduct was used in an elastomeric composite based on diene elastomers such as poly(styrene-cobutadiene) and poly(1,4-cis-isoprene) from Hevea brasiliensis. Comparison was made with a composite containing silica and a traditional coupling agent, a sulfur-based silane, bis(triethoxysilylpropyl)tetrasulfide (TESPT). SP appears to behave as a coupling agent for silica. To have similar properties for the SP and TESPT-based composites, tuning of the formulation of the composite with silica/SP has to be performed. Model reactions revealed the condensation of the OH of SP with the SiOR groups of an alkoxysilane, the reaction of the pyrrole ring with sulfur and a thiyl radical and the reaction of the sulfurated pyrrole ring with the unsaturation of squalene. SP appears thus able to establish covalent bonds with both silica and the unsaturated elastomer. With SP, the release of ethanol, which occurs from the silanization of silica with TESPT and is usually burned in industrial plants to give CO 2 , is avoided. This work paves the way for the development at the industrial scale of elastomeric composites which allow remarkable reduction of the carbon footprint of the tire technology.