A green, effective methodology for the preparation of water-based dispersions of poly(lactic acid) (PLA) for coating purposes is herein presented. The procedure consists of two steps: in the first one, an oil-in-water emulsion is obtained by mixing a solution of PLA in ethyl acetate with a water phase containing surfactant and stabilizer. Different homogenization methods as well as oil/water phase ratio, surfactant and stabilizer combinations were screened. In the second step, the quantitative evaporation of the organic provides water dispersions of PLA that are stable, at least, over several weeks at room temperature or at 4 °C. Particle size was in the 200–500 nm range, depending on the preparation conditions, as confirmed by scanning electron microscope (SEM) analysis. PLA was found not to suffer significant molecular weight degradation by gel permeation chromatography (GPC) analysis. Furthermore, two selected formulations with glass transition temperature (Tg) of 51 °C and 34 °C were tested for the preparation of PLA films by drying in PTFE capsules. In both cases, continuous films that are homogeneous by Fourier-transform infrared spectroscopy (FT-IR) and SEM observation were obtained only when drying was performed above 60 °C. The formulation with lower Tg results in films which are more flexible and transparent.

This is the "mobile" era, characterized by a growing demand of flexible substrates for novel products such as curved screens, folding smartphones, and wearable devices. In this framework, plastic electronics represents a suitable technology to replace silicon-based electronics. However, up to now, little attention has been devoted to rendering this technology more environmentally sustainable. It is thus necessary to develop new eco-designed devices that allow recycling of all the components and recovering the valuable materials through sustainable methods. For the first time, we report the fabrication of organic light emitting diodes made on an as-cast biopolymeric flexible substrate. Sodium alginate is a natural biodegradable polymer derived from brown algae; it is water-soluble and easy to manipulate for the realization of flat and transparent foils using an environmentally friendly process. Thus, the active stack can be directly deposited on the biopolymer substrate in a bottom-up architecture with no need for a pretreatment or a buffer layer. In addition, the devices can be disassembled and all of the valuable materials almost entirely recovered. This result opens up new and exciting opportunities for the fabrication of electronic and optoelectronic devices with a green platform for an ambient sustainable circular economy.

The synthesis of hydroxymethylfuroate macrocyclic oligoesters c(HMF)n promoted by an N-heterocyclic carbene (NHC) organocatalyst is herein presented together with the subsequent organocatalytic, entropically-driven ring-opening polymerization (ED-ROP) leading to the fully...

The polycondensation of diamines and dialdehydes promoted by an N‐heterocyclic carbene (NHC) catalyst in the presence of a quinone oxidant and hexafluoro‐2‐propanol (HFIP) is herein presented for the synthesis of oligomeric polyamides (PAs), which are obtained with a number‐average molecular weight (Mn) in the range of 1.7–3.6 kg mol−1 as determined by NMR analysis. In particular, the utilization of furanic dialdehyde monomers (2,5‐diformylfuran, DFF; 5,5’‐[oxybis(methylene)]bis[2‐furaldehyde], OBFA) to access known and previously unreported biobased PAs is illustrated. The synthesis of higher molecular weight PAs (poly(decamethylene terephthalamide, PA10T, Mn = 62.8 kg mol−1; poly(decamethylene 2,5‐furandicarboxylamide, PA10F, Mn = 6.5 kg mol−1) by a two‐step polycondensation approach is also described. The thermal properties (TGA and DSC analyses) of the synthesized PAs are reported.

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In this work, the rheological behavior of stable poly(lactic acid) (PLA) dispersions in water, intended for coating applications, was investigated. The newly prepared dispersion consists of PLA particles with an average diameter of 222 ± 2 nm based on dynamic light scattering (DLS) and scanning electron microscopy (SEM) analyses, at concentrations varying in the 5–22 wt % range. Xanthan gum (XG), a bacterial polysaccharide, was used as a thickening agent to modulate the viscosity of the formulations. The rheological properties of the PLA dispersions with different XG and PLA contents were studied in steady shear, amplitude sweep, and frequency sweep experiments. Under steady shear conditions, the viscosity of all the formulations showed a shear-thinning behavior similar to XG solutions in the whole investigated 1–1000 s –1 range, with values dependent on both PLA particles and XG concentrations. Amplitude and frequency sweep data revealed a weak-gel behavior except in the case of the most diluted sample, with moduli dependent on both PLA and XG contents. A unified scaling parameter was identified in the volume fraction (ϕ) of the PLA particles, calculated by considering the dependence of the continuous phase density on the XG concentration. Accordingly, a master curve at different volume fractions was built using the time–concentration–superposition approach. The master curve describes the rheological response of the system over a wider frequency window than the experimentally accessible one and reveals the presence of a superimposed β relaxation process in the high-frequency region.