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Characterization of films and film-forming solutions of chitosan/thermoplastic rice starch associations: Role of starch oxidation and plasticizer type in the molecular interactions
(2023-09-29)
Polysaccharide films are alternative sources to replace fossil-based compounds. This study aimed to use rice starch modified by gelatinization and oxidation processes. Different properties were observed after blending it with chitosan and polyols, as evaluated on the film-forming solutions by rheology. The interaction between chitosan and oxidized starch appeared higher, as the plasticizers exhibited a low effect on the rheological behavior. Polyols played an essential role in chitosan/gelatinized associations, driven ...
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A General Strategy for Increasing the Air Stability of Phosphines Including Primary Phosphines
(2023-08-31)
A general approach for increasing the air-stability of various primary phosphines in the absence of kinetic stabilization is presented that contrasts with previous interpretations, which were limited to specific phosphines. This contribution shows the synthesis of a series of air-stable primary phosphines Fc(CH₂)nPH₂, where n=0,1,2,3; and Fc=ferrocenyl, and their corresponding isolable primary phosphine oxides. It was demonstrated that the ferrocene moiety exerts an antioxidant effect on the primary phosphine group, ...
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Influence of Ethylene Oxide and Gamma Irradiation Sterilization Processes on the Properties of Poly-L-Lactic-Acid (PLLA) Materials
(2023-08-18)
In order to encourage the substitution of petrochemical polymers in medical technology with sustainable, bio-based materials, there is an urgent need for further investigations, especially data regarding their sterility performance. Within the scope of the investigations, selected material properties of poly-L-lactic-acid (PLLA), a specific type of poly(lactic-acid) (PLA), were analyzed before and after sterilization (using ethylene oxide or gamma irradiation) in order to investigate deviations in its chemical ...
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Controlled Ring Opening of a Tetracyclic Tetraphosphane with Twofold Metallocene Bridging
(2024-02-19)
A direct route to a doubly ferrocene bridged tetracyclic tetraphosphane 1 was developed via reductive coupling of Fe(CpPCl₂)₂ (2 a), where a chlorine terminated linear P₄-compound 3 could be identified as an intermediate. Selective P−P bond activation was further achieved by reacting 1 with elemental selenium or [Cp*Al]₄, where regioselective insertion of Se or Al atoms resulted in ferrocenylene bridged [P₄Se] (4) or [P₄Al] (7) moieties. Compound 7 can be transformed to a hydrogen terminated linear P₄ species, 8, ...
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Fluorescence microscopic investigation of PCE superplasticiser adsorption in calcined clay blended cement
(2024-03-31)
Global efforts to minimise carbon dioxide emissions are also leading to attempts to use calcined clays (CC) as a partial substitute for cement in concrete. While the hydration mechanism of such CC blended cements is now well understood, the range of effective admixtures like polycarboxylate ethers (PCE) is limited. There are PCE types that promise relatively high effectiveness, but the mechanisms of action are not yet sufficiently understood. For a detailed understanding of the adsorption of such PCEs, spatially ...
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Chitosan hydrogels enriched with bioactive phloroglucinol for controlled drug diffusion and potential wound healing
(2024-04)
We report a facile strategy to prepare chitosan (CS) hydrogels that eliminates the need for chemical crosslinking for advanced biomedical therapies. This approach gives controlled properties to the hydrogels by incorporating a natural bioactive phenolic compound, phloroglucinol (PG), into their microstructure. The adsorption of PG onto CS chains enhanced the hydrogels' antioxidant activity by up to 25 % and resulted in a denser, more entangled structure, reducing the pore size by 59 μm while maintaining porosity above ...