Amphiphilic Biodegradable Poly(ϵ-caprolactone)-Poly(ethylene glycol) – Poly(ϵ-caprolactone) Triblock Copolymer Synthesis by Maghnite-H+as a Green Catalyst

Facile and eco-friendly method of starch nanocrystals esterified with oleic acid using natural clay as a catalyst: Synthesis, Box-Behnken optimization, characterization and analysis of thermal and antioxidant properties

This study investigates the synthesis of corn starch nanocrystals (SNCs) via sulfuric acid hydrolysis. Esterification of oleic acid (OA) with SNCs was carried out using Maghnite-H+ as a catalyst, a non-polluting, eco-friendly proton-exchanged montmorillonite-based green catalyst suitable for various chemical processes. Optimization of synthesis parameters, including reaction temperature, duration, and catalyst quantity, was conducted using response surface methodology (RSM) with a central composite design incorporating three factors and three levels. Optimal conditions for achieving a high degree of substitution (DS) were determined as follows: 21.27 h reaction time, 106.39 °C temperature, and 15.17 % (by weight of starch) Maghnite-H+ catalyst, with a molar ratio of OA to anhydrous glucose units of 3:1. Characterization of the esterification product was performed using FTIR spectroscopy, while electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed significant changes in appearance and internal structure post-esterification. Thermal analysis indicated lower heat resistance for SNCs-OA compared to native starch and SNCs. Furthermore, both esterified and unmodified SNCs exhibited antioxidant properties, with activity comparable to standard antioxidant vitamin C (ascorbic acid), as measured by their ability to neutralize free radicals, which increased with SNCs concentration. This comprehensive study offers valuable insights into the synthesis, characterization, and functional properties of SNCs-OA.

A New Green Catalyst for Synthesis of bis-Macromonomers of Polyethylene Glycol (PEG)

A new method to synthesise polyethylene glycol dimethacrylate (PEGDM) with various molecular weights (1000, 3000, 6000 and 8000 g/mol) of polyethylene glycol (PEG) has been developed. This technique consists in using Maghnite-H+ as eco-catalyst to replace еriethylamine, which is toxic. Maghnite-H+ is a proton exchanged montmorillonite clay which is prepared through a simple exchange process. Synthesis experiments are performed in solution using dichloromethane as solvent in the presence of methacrylic anhydride. The effect of reaction time, temperature, amount of catalyst and amount of methacrylic anhydride is studied in order to find the optimal reaction conditions. The synthesis in solution leads to the best yield (98 %) at room temperature for the reaction time of 5 h. The structure of the obtained macromonomers (PEGDM) is confirmed by FTIR, 1H NMR and 13C NMR, where the methacrylate end groups are clearly visible. Thermogravimetric analysis (TGA) is used to study the thermal stability of these obtained macromonomers. The presence of unsaturated end group was confirmed by UV-Visible analysis.

Direct Synthesis and Characterization of Photo-Crosslinkable Biodegradable PLA-PEG-PLA Ttiblock Copolymer with Methacrylates Functions by Green Montmorillonite Clay Catalyst

Di-methacrylated PLA-PEG-PLA triblock copolymers of polylactide and polyethylene glycol were synthesized in one-step process by bulk cationic polymerization of lactide in the presence of PEG with different average molecular weights, using Maghnite-H+, an acidic montmorillonite clay, as a solid non-toxic catalyst. The obtained di-methacrylated copolymer was analyzed by 1H NMR and DSC. The effect of Maghnite-H+ proportions and PEG average molecular weight on the copolymerization and methacrylation yields and on average molecular weight of the resulting copolymers was studied.

Triblock and pentablock copolymerizations of ε-caprolactone with l-lactide catalyzed by N-heterocyclic carbene

B-12-C-4imY exhibit the characteristics of a “living” ROP and highly active for the ROP of LLA and ε-CL. Copolymers prepared possess predictable molecular weights, narrow polydispersities, and high end-group fidelity.