EQCM Analysis of the Insertion Phenomena in a n-Doped Poly-Alkyl-Terthiophene With Regioregular Pattern of Substitution

In the present work, we have undertaken the study of the n-doping process in poly-3,3″-didodecyl-2,2′:5′,2″-terthiophene (poly-33″-DDTT) employing the electrochemical quartz crystal microbalance (EQCM). The present study aims at understanding how cathodic charge in n-doped poly-33″-DDTT is compensated. For this purpose, the in situ analysis of the variations of the polymeric mass has been considered. Poly-33″-DDTT was obtained as a thin coating onto a metallic substrate via the anodic coupling of the corresponding monomer 3,3″-didodecyl-2,2′:5′,2″-terthiophene (33″-DDTT). When subjected to electrochemical n-doping in the polarization interval -2.5 ≤ Eappl ≤ 0 V vs. Ag/Ag+, the films of poly-33″-DDTT varied their mass according to a mechanism of cations insertion during n-doping and cations extraction during polymer neutralization. In fact, the electrochemical doping of polythiophenes requires the accompanying exchange of charged species to maintain the electroneutrality within the structure of the polymer in all states of polarization. At the end of a full electrochemical cycle (consisting of the n-doping and the successive neutralization of poly-33″-DDTT), the polymer retains a fraction of the mass acquired during n-doping, thus manifesting the phenomena of mass trapping. The combined analysis of electrochemical and microgravimetric data suggests that poly-33″-DDTT in the n-doped state undergoes (or electrocatalyzes) uncontrolled electrochemical reactions that are not accompanied by mass variations

Ionic Push–Pull Polythiophenes: A Further Step towards Eco-Friendly BHJ Organic Solar Cells

Four new conjugated polymers alternating benzothiadiazole units and thiophene moieties functionalized with ionic phosphonium or sulfonic acid salts in the side chains were synthesized by a postfunctionalization approach of polymeric precursors. The introduction of ionic groups makes the conjugated polymers soluble in water and/or polar solvents, allowing for the fabrication of bulk heterojunction (BHJ) solar cells using environmentally friendly conditions. All polymers were fully characterized by spectroscopic, thermal, electrochemical, X-ray diffraction, scanning electron, and atomic force techniques. BHJ solar cells were obtained from halogen-free solvents (i.e., ethanol and/or anisole) by blending the synthesized ionic push–pull polymers with a serinol-fullerene derivative or an ionic homopolymer acting as electron-acceptor (EA) or electron-donor (ED) counterparts, respectively. The device with the highest optical density and the smoothest surface of the active layer was the best-performing, showing a 4.76% photoconversion efficiency

Multifunctional platform based on electrospun nanofibers and plasmonic hydrogel. A smart nanostructured pillow for near-infrared light-driven biomedical applications

Multifunctional nanomaterials with the ability to respond to near-infrared (NIR) light stimulation are vital for the development of highly efficient biomedical nanoplatforms with a polytherapeutic approach. Inspired by the mesoglea structure of jellyfish bells, a biomimetic multifunctional nanostructured pillow with fast photothermal responsiveness for NIR light-controlled on-demand drug delivery is developed. We fabricate a nanoplatform with several hierarchical levels designed to generate a series of controlled, rapid, and reversible cascade-like structural changes upon NIR light irradiation. The mechanical contraction of the nanostructured platform, resulting from the increase of temperature to 42 °C due to plasmonic hydrogel-light interaction, causes a rapid expulsion of water from the inner structure, passing through an electrospun membrane anchored onto the hydrogel core. The mutual effects of the rise in temperature and water flow stimulate the release of molecules from the nanofibers. To expand the potential applications of the biomimetic platform, the photothermal responsiveness to reach the typical temperature level for performing photothermal therapy (PTT) is designed. The on-demand drug model penetration into pig tissue demonstrates the efficiency of the nanostructured platform in the rapid and controlled release of molecules, while the high biocompatibility confirms the pillow potential for biomedical applications based on the NIR light-driven multitherapy strategy

Bulk heterojunction solar cells: the role of alkyl side chain on nanoscale morphology of sulfur overrich regioregular polythiophenes/fullerene blends.

Regioregular HH-TT poly(3,3’-thioalkylbithiophene)s bearing branched or linear alkyl side-chain substituents (PT2SR) have been synthesized and characterized in order to investigate their behavior, when used as electron donor components in blend with a fullerene derivative (PCBM) as electron acceptor, in air-processed photovoltaic solar cells with bulk heterojunction architecture. The optoelectronic characteristics, energy gap, nanoscale morphology and crystallinity of the blends (PT2SR/PCBM) were examined by UV–vis spectroscopy, cyclic voltammetry, Kelvin Probe Force Microscopy and X-ray diffraction. We demonstrate that thioalkyl substituents are able to influence the PCBM self-assembly and the morphology of the polymeric film, important parameters to maximize the efficiency of solar cell. In particular, the presence of chemical branching in the side chain of the sulfur overrich polythiophene backbone favors the formation of PCBM clusters, of size about 100±30 nm as confirmed by X-ray diffraction and KPFM measurements, and facilitates the intermixing between the donor and acceptor materials at the nanoscale level, thus determining a corresponding increase in device performance

METHACRYLIC POLYMERS BEARING IN THE SIDE-CHAIN AN OPTICALLY ACTIVE MOIETY LINKED TO THE TRANS-4-AZOBENZENE CHROMOPHORE: CHIROPTICAL PROPERTIES OF POLY[(S)-(+)-N-METHYL-(2-METHACRYLOYLOXYPROPANOYL)-4-AMINOAZOBENZENE]

The synthesis by radical homopolymerization of a novel optically active methacrylic polymer containing a side-chain chiral moiety linked to a photochromic chromophore has been carried out starting from the related monomer trans-(S)-(+)-N-methyl-(2-methacryloyloxypropanoyl)-4-aminoazobenzene. The chiroptical properties in solution of the polymer have been investigated by circular dichroism and compared with those of the corresponding low molecular weight model compound, trans-(S)-(+)-N-methyl-(2-pivaloyloxypropanoyl)-4-aminoazobenzene. The optical activity displayed by the polymer is discussed in terms of extent of chiral conformations assumed by the macromolecules as a consequence of dipole-dipole interactions between the azoaromatic chromophores