Towards Thermally Reversible Networks Based on Furan-Functionalization of Jatropha Oil.

A novel biobased monomer for the preparation of thermally reversible networks based on the Diels-Alder reaction was synthesized from jatropha oil. The oil was epoxidized and subsequently reacted with furfurylamine to attach furan groups via an epoxide ring opening reaction. However, furfurylamine also reacted with the ester groups of the triglycerides via aminolysis, thus resulting in short-chain molecules that ultimately yielded brittle thermally reversible polymers upon cross-linking via a Diels-Alder reaction. A full-factorial experimental design was used in finding the optimum conditions to minimize ester aminolysis and to maximize the epoxide ring opening reaction as well as the number of furans attached to the modified oil. The optimum conditions were determined experimentally and were found to be 80 °C, 24 h, 1:1 molar ratio, with 50 mol % of LiBr with respect to the modified oil, resulting in 35% of ester conversion, 99% of epoxide conversion, and an average of 1.32 furans/triglyceride. Ultimately, further optimization by a statistical approach led to an average of 2.19 furans per triglyceride, which eventually yielded a flexible network upon cross-linking via a Diels-Alder reaction instead of the brittle one obtained when the furan-functionalization reaction was not optimized.

Insights in starch acetylation in sub- and supercritical CO2.

An in-depth study on the acetylation of starch with acetic anhydride (Ac(2)O) and sodium acetate (NaOAc) as the catalyst in pressurized carbon dioxide (scCO(2)) in a broad pressure range (8-25MPa) and a temperature of 90°C is provided. Highest degrees of substitution (DS) of 0.29 (1h reaction time) and 0.62 (24h reaction time) were found near the critical point of the mixture (15MPa). The phase behavior of the system CO(2), starch and acetic anhydride (Ac(2)O) was studied in a high pressure view cell. The critical points were a clear function of the temperature and increased from the range of 9.4-10MPa to 14.5-14.8MPa when going from 50 to 90°C (Ac(2)O mole fraction at the critical point in the range of 0.08-0.09). Acetylation experiments with a range of starch particles sizes showed a clear relation between the DS and the particle size.