PREPARATION OF CHITOSAN GRAFT COPOLYMERS AND STUDY OF THEIR WATER-SWELLING PROPERTIES

In this work, graft copolymers of chitosan with trimethylmethacryloxyethylammonium methyl sulfate were synthesized by the method of controlled radical polymerization, and it was found that replacing the dimethylformamide aprotic solvent with water increases the degree of grafting. With the aim of the possible use of chitosan copolymers as a functional component for regulating the water-swelling properties of elastomers, the kinetics of swelling of the samples was investigated. An increase in the degree of swelling of the copolymers in comparison with the initial chitosan was revealed, and the influence of the molecular weight and the conditions of their synthesis was established.

Electrochemical Incorporation of Carbon Dioxide into Fluorotoluene Derivatives under Mild Conditions

One of the main challenges to combat climate change is to eliminate or reuse Carbon dioxide (CO2), the largest contributor to the greenhouse gases that cause global warming. It is also important to synthesize compounds through greener technologies in order to obtain more environmentally friendly solutions. This study describes the electrocarboxylation process of α,α,α-trifluorotoluene using different working electrodes (glassy carbon, silver and copper) and electrolytes (polar aprotic solvent and ionic liquid). Carboxylated compounds were obtained in the same way in both electrolytic medias with more than 80% conversion rates, high yields, good selectivity, and moderate efficiencies using silver and copper as cathodes in organic electrolytes and ionic liquids.

Hyaluronic Acid Functionalization with Jeffamine® M2005: A Comparison of the Thermo-Responsiveness Properties of the Hydrogel Obtained through Two Different Synthesis Routes

Hyaluronic acid (HA) of different molar masses (respectively 38,000, 140,000 and 1,200,000 g.mol−1) have been functionalized with a commercial poly(etheramine), Jeffamine® M2005, in order to devise physical thermo-responsive hydrogels. Two routes have been studied, involving the use of either water for the first one or of N,N’-Dimethylformamide (DMF), a polar aprotic solvent, for the second one. In the case of the water route, the reaction was performed using a mixture of N-(3-Dimethylaminopropyl)-N’-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) as coupling reagents. The reaction was optimized while making sure no free M2005 remained in the final material, leading to M2005 grafting degrees of about 4%, which enabled the formation of hydrogels by increasing the temperature. In the case of the organic solvent route, propylphosphonic anhydride T3P® was used as a coupling reagent in DMF, resulting in a M2005 grafting degree of around 8% with better thermo-responsive properties of HA-g-M2005 compared to those obtained when the reaction was performed in water. However, the reaction systematically led to covalent cross-linking in the case of the HA, with the highest starting molar masses resulting in a very different rheological behaviour and with higher gel strength retaining thermo-responsive behaviour but being only poorly soluble in water.