Highly polar fluorinated polymers such as Polyvinylidene Fluoride-Trifluoroethylene (P(VDF-TrFE)) are emerging materials in the field of flexible organic electronics because of their numerous applications as actuators, sensors, or energy harvesters. Due to the high polarity of C-F bonds, cooperative dipole orientation in crystalline domains can be induced and are primarily responsible for the electroactive properties of these polymers. The processing of these materials into thin films can be performed by solution printing or casting, offering a versatile and scalable method for the production of highly functional layers. Nevertheless, the implementation of such layers in practical devices is directly related to the rheological properties of the electroactive inks that determine the printability regimes leading to stable and functional electroactive layers. We evaluated the viscoelastic behavior of P(VDF-TrFE) solutions for solvents of different polarity, ranging from the dilute to the concentrated regime. From these measurements, we extracted using a scaling approach several polymer-solvent parameters that are highly dependent on the polymer composition and solvent polarity. Complementary light scattering measurements further correlated the polymer conformational changes with the polymer-solvent affinity extracted from the rheological analysis. Finally, we examined the impact of the ink formulation on the fabrication of PVDF-based electroactive devices by the screen-printing method in order to establish a correlation between the rheological parameters of the ink and the resistance to breakdown during the polarization cycles. In conclusion, this study provided a deeper understanding on the influence of the polymer dissolution on the printability regimes towards high performance electroactive layers.

Ionic liquids (ILs) and their solutions in DMSO dissolve biopolymers; these solutions are employed for the synthesis of biopolymer derivatives. We studied the solubilization of cellulose (Cel) in mixtures of 11 amino acid-based ionic liquids (AA-ILs) and DMSO (DMSO = 0.6 and T = 70 C); the cations are 1-(n-butyl)-3-methylimidazolium (8 AA-ILs) and 1-(n-butyl)-2,3-dimethylimidazolium (3 AA-ILs). We determined the following properties for pure AA-ILs and AA-ILs-DMSO mixtures: Empirical polarity (ET (WB)); Lewis acidity (SA), Lewis basicity (SB), molecular volume (VM) and a function of the refractive index, (n). For both cases, we obtained good correlations between ET (WB) and the other parameters; SA and SB are important; VM term has a negative sign. We correlated Celmax,% with these solvent parameters and obtained a correlation whose quality increased when the AA-ILs of Ser and Thr were removed; SA and SB are important; SA and VM, have negative signs. Molecular dynamics (MD) calculations showed that the inefficiency of Ser and Thr AA-ILs are due to intramolecular H-bonding within the AA anions, leading to their weak interaction with Cel. Our results showed: (i) SA and SB are the most important solvent parameters for interactions of AA-ILs with DMSO, and the binary solvent with Cel; (ii) There is a linear correlation between Celmax,% and the number of AA-IL-Cel H-bonds; (iii) The composition of the Cel solvation layer is different from that of bulk solvent composition. Cel dissolved in Ala-based IL-DMSO was regenerated as nanoparticles. We thank FAPESP and CNPq for financial support

PEN (polyethylene naphthalate) is a polyester with a chemical structure similar to PET (polyethylene terephthalate), which makes these polyesters miscible and capable of being processed under similar conditions. These polymers can also be chemically recycled together, resulting in a copolymer with enhanced properties compared to raw PET.
PEN exhibits superior performance characteristics such as durability, heat resistance, dimensional stability, and significantly lower oxygen permeability. However, its higher cost limits its use to applications where PET does not meet the required standards, such as in reusable bottles or containers for oxygen-sensitive products.
Recently, the range of PEN applications has been expanding, and its production has been increasing, leading to a gradual decline in prices and improved availability.
This work investigates the application of PEN as a fluorescent material. For this purpose, PEN was synthesized through the polycondensation of ethylene glycol and dimethyl naphthalene-2,6-dicarboxylate, using titanium butoxide as a catalyst. The fluorescence intensity of the obtained samples was tested and compared with fluorescence intensity of PEN foils available on the market. The results demonstrated the potential of using PEN as a fluorescent material emitting blue visible light.
Keywords: PEN, fluorescence

This work focuses on improving the piezoelectric performances of Poly(L-Lactide) (PLA) films for replacing conventional electroactive ceramics and fluoropolymers in emerging applications. Attractively, the piezoelectricity of optically active PLA originates from uniaxial orientation rather than energy-intensive electric puling. An industrially-relevant extrusion-orientation process (machine-direction orientation, MDO) coupled with post-annealing treatments arguably promotes an efficient production of piezoelectric films with high orientation states.


Linking structure-property relationships with processing conditions are primarily studied. Precise piezoelectric measurements and special structural analysis (polarized infrared spectroscopy and x-ray diffractions) were conducted. A prediction model¹ was proposed to decouple the piezoelectricity of PLA into contributions of crystalline, meso-, and amorphous phases. Current work revealed that the oriented amorphous phase is indispensable with an extrapolated piezoelectric contribution up to 7 pC/N. The MDO was proved effective for the amorphous orientation because its high deformation rate prohibits amorphous relaxation. Oriented crystals are attested to the highest piezoelectric contribution². This research revealed that post-annealing treatments under tension above 100 ℃ are fundamental to significantly producing fully oriented crystals. Annealing temperatures up to 160 - 170 ℃ are helpful to boost fully oriented crystals up to 52% and obtain densified α crystals. This crystal has a marginally elevated piezoelectric coefficient than the conventional disordered α' crystals. Overall, PLA films produced by MDO and post-annealing displayed higher shear piezoelectricity (13 pC/N) than the state-of-the-art value with a 30% enhancement.


Finally, our studies are focused on emerging applications of these piezoelectric films. Examples are vibrational energy harvesters and water remediation under ultrasound stimulations.

Isoelectronic and isosteric substitution of selected CC units in π-conjugated organic materials by the main-group element couple BN has led to various novel hybrid materials with intriguing properties and functions.[1] Some time ago, we reported the first poly(p-phenylene iminoborane), which is derived from poly(p-phenylene vinylene) (PPV) by replacement of its vinylene with B=N moieties (i.e., BBNN-PPV).[2]
Now we targeted a BN/CC isostere of poly(thiophene vinylene) (PTV), namely, poly(thiophene iminoborane) (BBNN-PTV),[3] as well as mixed copolymers combining both PPV and PTV building blocks (i.e., BN-PAVs), showing pronounced solid-state fluorescence.[4] We recently also accomplished the synthesis of a strictly alternating BN-PPV, which show dual fluorescence emission and stimuli-responsive properties.[5] In addition, we achieved the incorporation of valence isoelectronic B=P moieties into the PPV framework, thus leading to the first poly(p-phenylene phosphaborene) (BBPP-PPV) as well as BBPP-PPV-type oligomers, which exhibit a highly planar backbone with effective conjugation across the B=P units and further redshifted absorption and emission properties.

The perpetual race to scaling down the size of microelectronic devices is intrinsically dependent on the production of transistors with complex shapes and dimensions of only few nanometers, in which an extreme control of the amount and position of dopant atoms in the semiconductor substrate is present.
In this perspective, in the last ten years our research group has developed an innovative procedure that uses polymer materials to easily and cheaply control the amount of dopant atoms deposited on silicon substrates1. This technology, also called polymeric precision doping, is based on functional polymers with controlled molecular weights and narrow mass distributions, which are engineered with a dopant atom in the polymer end-group. When these polymers are reacted on silicon by a grafting to reaction, polymer brushes with a precise amount of polymer chains, and therefore a precise number of dopant atoms, are obtained due to the self-limiting nature of the grafting to reaction2.
Furthermore, after a first generation of dopant polymers synthesized by controlled radical polymerization techniques, a new step towards total control of doping has been made with perfectly monodisperse polypeptoids synthesized with an automatic polypeptide synthesizer3. Moreover, while most of these technologies have been developed for phosphorus-based doping processes, complementary boron-containing polymers have recently been synthesized.
The path that led to the development and refinement of these innovative polymers will be the subject of this communication, with the aim of showing the opportunities that such polymers are able to offer in the unconventional field of microelectronics.