Marco Aldo Ortenzi

Comparison of cellulose nanocrystals obtained by sulfuric acid hydrolysis and ammonium persulfate, to be used as coating on flexible food-packaging materials

Cellulose nanocrystals (CNCs), extracted from trees, plants, or similar cellulose-containing materials, can be used in combination with other materials to improve their performance or introduce new applications. The main purpose of this study was to compare and understand the potentialities, as coatings for Poly(ethylene terephthalate) films, of CNCs obtained starting from the same cotton linters by two different processes: sulfuric acid hydrolysis and a less common treatment with ammonium persulfate (APS), able to provide also a cellulose oxidation. The results showed that CNCs produced through the APS treatment showed higher charge densities, due to the carboxylic groups formed during the process, higher crystallinity, higher clarity of the solution and, as a consequence, higher transparency of the coating. These characteristics provide a higher oxygen barrier with respect to the CNCs produced by the H2SO4 treatment, together with the availability of active sites for potential surface modification or chemical grafting. Both CNC coatings showed oxygen permeability coefficients that were lower than synthetic resins commonly used in flexible packaging. Furthermore, they did not significantly affect the optical properties of the substrate, while revealing good friction coefficients. Due though to the moisture sensitivity of the coating and its non-sealable nature, similar to EVOH or PVOH oxygen barrier synthetic resins, CNCs developed using APS will need to be laminated with another plastic layer such as a polyolefin. They could then be used to enhance the final properties of packaging solutions as an alternative to conventional food-packaging materials for perishable food products, while reducing their environmental impact with a thin layer of a bio-based polymer.

Homogeneous synthesis and characterization of sulfonated polyarylethersulfones having low degree of sulfonation and highly hydrophilic behavior

In the present paper, the wettability of polyarylethersulfones (PESs) was promoted through the controlled introduction of sulfonic groups in PES polymeric chain. Homogeneous synthesis using a sulfonated comonomer introduced sulfonic groups while exerting a tight control over the degree of sulfonation (DS) and avoiding the undesired side reactions brought about by heterogeneous sulfonation reactions. A series of sulfonated polyarylethersulfones (SPESs) with very low amounts of sulfonic groups - 0.5, 0.75, and 1 meq SO3-*g-1 of polymer - was synthesized via polycondensation using 4,4’-difluorodiphenylsulfone, 4,4’-dihydroxydiphenyl and a sulfonated comonomer, 2,5-dihydroxybenzene-1-sulfonate potassium salt. The presence of sulfonic groups was confirmed by Fourier transform infrared (FTIR) spectra; the macromolecular structure and the real DS of SPESs were determined by 1H NMR; the molecular weights were investigated by size exclusion chromatography (SEC); ion exchange capacity (IEC) values, measured by potentiometric titration, are in good agreement with the experimental DS. The polyelectrolyte effect was studied on intrinsic viscosity (IV) measurements. The effect of DS on the thermal properties of SPES membranes was studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC); wetting properties were characterized by static water contact angle (SWCA) measurements on membranes obtained via solution casting. The results showed that an increased DS results in higher glass transition temperatures (Tg) and lower water contact angles, the latter dropping from

In situ film forming fibroin gel intended for cutaneous administration

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The Effect of Moisture on Cellulose Nanocrystals Intended as a High Gas Barrier Coating on Flexible Packaging Materials

91¯∘ to

Combining control of branching and sulfonation in one-pot synthesis of random sulfonated polyarylethersulfones: effects on thermal stability and water retention

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Modified α,α′-trehalose and d-glucose: green monomers for the synthesis of vinyl copolymers

43¯∘ as DS was raised from 0 to 1.0 meq SO3-*g-1. This work demonstrates that homogeneous synthesis of SPES is an efficient way to prepare SPES membranes with tightly controlled DS and enhanced hydrophilic properties, in particular, an excellent hydrophilic SWCA even at very low amounts of sulfonic moieties.