A comparative study of electrochemical, spectroscopic and structural properties of phenyl, thienyl and furyl substituted ethylenes

a detailed electrochemical and photophysical comparative study of three parallel series of phenyl, thienyl and furyl substituted ethylenes has been carried out, implemented by the computational calculation of selected terms. Relationships have been highlighted between molecular structure (number and type of aromatic rings) and important functional properties (in particular, electronic features and oligomerization ability). Interestingly, some of the studied heteroaryl-ethylenes show emission in the solid state displaying an aggregation-induced emission behavior

An Adaptive Learning with Gamification & Conversational UIs: The Rise of CiboPoliBot

Gamification in the era of chatbots is a novel way to engage users with the chatbot application. When developing a gamified chatbot system, there are factors related to user types (ages, gender and others) that we should consider to effectively integrate the game elements into the chatbot while targeting the right audience. In this study, we discuss the development of an educational chatbot game 'CiboPoli', that's specialised in teaching children about healthy lifestyle through an interactive social game environment. The presented game is based on a paper prototype that we developed to teach primary school students about healthy diet and food waste management. The current approach will be more engaging and pose AI capabilities. This is still a work in progress and we plan to improve its design by incorporating additional components, such as dialog management module, user-specific knowledge module or machine learning module. Future work will be devoted to integrating machine learning to automatically identify learners emotions and provide personalised suggestions. Moreover, we tested the initial prototype with school students and found that it outperforms the paper version. Future work will focus on applying it to other domains and demographics

Layer by layer control of wettability in nanocomposite films

Photopolymerized nanocomposite films of polystyrene and TiO2 nanorods are found to change their surface wettability characteristics in a controlled manner, depending on both the substrate used and on the number of film layers realized. The constituents of the nanocomposite solutions, namely styrene monomers and TiO2 nanorods, interact differently with the surface on which they are deposited, depending on its wettability. This interaction influences their dispersion along the depth and on the surface of the photopolymerized film, impacting on its wetting properties. We demonstrate that that the diverse amount of TiO2 nanorods exposed each time on the surface of the final film, which depends on the wettability of the surface lying underneath, is responsible for the layer-by layer alternated surface characteristics. Moreover, due to the presence of TiO2 nanorods on the sample's surface, the wettability characteristics can be tuned in a reversible manner upon UV irradiation and vacuum storage cycles

Layer by layer control of wettability in nanocomposite films

Photopolymerized nanocomposite films of polystyrene and TiO2 nanorods are found to change their surface wettability characteristics in a controlled manner, depending on both the substrate used and on the number of film layers realized. The constituents of the nanocomposite solutions, namely styrene monomers and TiO2 nanorods, interact differently with the surface on which they are deposited, depending on its wettability. This interaction influences their dispersion along the depth and on the surface of the photopolymerized film, impacting on its wetting properties. We demonstrate that that the diverse amount of TiO2 nanorods exposed each time on the surface of the final film, which depends on the wettability of the surface lying underneath, is responsible for the layer-by-layer alternated surface characteristics. Moreover, due to the presence of TiO2 nanorods on the sample's surface, the wettability characteristics can be tuned in a reversible manner upon UV irradiation and vacuum storage cycles

Polybenzofulvenes-based blends with benzothiadiazole and perylene diimide derivatives emitting from yellow to the deep-red by resonant energy transfer processes

The ability of a π-stacked polybenzofulvene derivative to self-assemble with emissive dyes in supramolecular organizations that reduce unwanted microaggregation processes is demonstrated by a study of the photophysical properties of its blends with benzothiadiazole and two perylenediimide derivatives. Films displaying efficient emissions with quantum yields of 0.85 in the yellow, 0.54 in the red, and 0.39 in the deep-red regions are obtained thanks to combined homo- and hetero-resonant energy transfer processes from the polymer excimer-like π-stacked chromophores to the emitting dyes

Spontaneous liquid flow in microfluidic systems by UV irradiation of the hybrid polymer/TiO2 nanorods channels

A method for enhancing the surface wettability of PDMS microchannels used in microfluidic devices, is presented. Colloidal TiO2 nanorods are mixed in a PDMS solution that was used subsequently to realize parallel microchannels, through a replica molding procedure. TiO2 has the intrinsic capability of increasing dramatically its hydrophilicity upon UV irradiation. Due to this property, incorporating TiO2 nanofillers into the PDMS microchannels we manage to induce their hydrophobic-to-hydrophilic conversion upon UV irradiation. This conversion is essential for water to fill the microfluidic channels, in contrast to what happens for the non-irradiated nanocomposite or pure PDMS channels, which are characterized by high hydrophobicity and do not allow water to penetrate. The reversibility of the wettability changes permits to the microchannels to recover their original hydrophobicity

Red and deep-red emissive polymeric nanoparticles based on polybenzofulvene and perylenediimide derivatives

Polymeric nanoparticles obtained by co-aggregation of a polybenzofulvene derivative with bulky substituted perylene diimide dyes in tetrahydrofuran/water mixtures display emission color tunable from blue to red, or deep-red, thanks to energy transfer processes from the polymer to the emissive dyes activated by nanoparticle shrinking. At high water concentrations the presence of well emissive perylene diimide dye micro-aggregates within the polymer nanoparticles limits the FRET efficiency leading to a combined emission from both the polymer (blue) and the dyes (red and deep-red). The optical properties of the NPs are retained also in the solid state where a weak blue contribution of the polymer emission is observed providing multicolor emission in the films obtained by NPs deposition

Red and deep-red emissive polymeric nanoparticles based on polybenzofulvene and perylenediimide derivatives

Polymeric nanoparticles obtained by co-aggregation of a polybenzofulvene derivative with bulky substituted perylene diimide dyes in tetrahydrofuran/water mixtures display emission color tunable from blue to red, or deep-red, thanks to energy transfer processes from the polymer to the emissive dyes activated by nanoparticle shrinking. At high water concentrations the presence of well emissive perylene diimide dye micro-aggregates within the polymer nanoparticles limits the FRET efficiency leading to a combined emission from both the polymer (blue) and the dyes (red and deep-red). The optical properties of the NPs are retained also in the solid state where a weak blue contribution of the polymer emission is observed providing multicolor emission in the films obtained by NPs deposition

Near IR to Red Up-Conversion in Tetracene/Pentacene Host/Guest Cocrystals Enhanced by Energy Transfer from Host to Guest

Solid-state materials with up-conversion activity at low power excitation are highly desirable for several optoelectronic applications. In this work we show that a host/guest cocrystal of tetracene/pentacene (Tc/Pc) exhibits a near-infrared (NIR) excited up-conversion process. Förster resonant energy transfer (FRET) from Tc to Pc is enhanced by NIR excitation with respect to visible excitation. A triplet-triplet annihilation mechanism activated by the pentacene molecules acting as traps in the host crystal is proposed and confirmed by time-resolved fluorescence spectra. TDDFT calculations on model molecular clusters support this hypothesis, highlighting the existence of strong excitonic interactions which is a necessary prerequisite for good transport of photogenerated excitons in Pc-doped Tc crystals