Nowadays the use of vegetable oils as polymer precursors is the subject of growing interest in the academic and industrial communities. Many synthetic pathways can be pursued from natural vegetable oils to yield different functionalized derivatives – also called synthons – and polymers, such as polyesters, polyurethanes, polyamides, etc. Herein, we widely overview recent progress in the preparation of vegetable oil-based thermoplastic polymers and, more precisely, thermoplastic polyesters and polyurethanes. Extra focus is also placed on the synthesis sustainability of these polymeric materials via atom efficient techniques, “green” catalyses and processes. The achievable bio-sourced polymers cover a wide range of thermo-mechanical properties that can respond to most of the current applications of synthetic polymers.
18 December 2018 in ACS Sustainable Chemistry & Engineering
As we passed the 20th anniversary of the publication of the twelve principles of green chemistry, the sustainable modification of cellulose, being the most abundant bio-based polymer, is certainly worth considering. Many researchers work on an efficient valorization of this renewable resource due to its manifold and promising application possibilities, but very often the use of non-sustainable approaches (i.e. solvents, reactants and modification approaches) only addresses the renewability aspect of cellulose, while neglecting most or all of the other principles of green chemistry. In this review, we have employed the use of E-factors together with basic toxicity information to compare between various approaches for homogeneous cellulose modification. This approach, though simple and certainly not overarching, can provide a quick and useful first sustainability assessment. Therefore, in order to achieve a truly sustainable modification of cellulose, its renewability combined with mild and efficient reaction protocols is crucial in order to obtain sustainable materials that are capable of reducing the overall negative impact of today’s fossil-based polymeric materials.
28 June 2018 in ACS Sustainable Chemistry & Engineering
Activated 5-membered cyclic carbonates were prepared from glycerol and fatty acid derivatives. Ester and ether moieties were introduced in the β position to the cyclic carbonate, in order to enhance its reactivity towards amines. 1H NMR kinetic investigation of the aminolysis of these cyclic carbonates demonstrated a higher reactivity compared to the one of alkyl substituted cyclic carbonates. In the case of ester-activated carbonates, a reactivity similar to the one of 6-membered ring cyclic carbonates was observed. Moreover, these carbonates exhibited amidation side-reactions with amines that could be however prevented by decreasing the temperature to room temperature. Poly(hydroxyurethane)s (PHUs) were then synthesized from these activated 5-membered ring cyclic carbonates at 70 °C in DMF (1 mol L−1) and exhibited molar masses up to 13 700 g mol−1 with Tg in the range −26 to −10 °C.