Evaluation of the Parameters of Poly(Butylene succinate) Enzymatic Polymerization

Poly(butylene succinate) (PBS) is a bio-based and biodegradable polyester that can be used in numerous applications, ranging from clothing to food packaging and from the car industry to the biomedical sector (e.g., drug release systems). The conventional polymerization method of PBS requires the presence of metal-based transesterification catalysts (e.g., titanium-based catalysts) and high reaction temperatures (T > 150 °C). However, under these conditions side reactions may occur along with undesirable yellowing. Green polymerization routes such as biocatalysis are being developed. However, there is a very limited literature on the enzymatic synthesis of PBS. Additionally, in most of the works where high-molecular-weight PBS is produced from the typical monomers (BDO and DES), several drawbacks, e.g., the use of various solvents for polymer isolation and the requirement of high vacuum for by-products removal may impede the process being scaled up. On that basis, an eco-friendly, solvent-free, enzyme-based process for the production of PBS was applied. It was conducted in two steps with the use of Novozym 435: the first at 40 °C, under atmospheric pressure for 24 h, and the second at 90 °C, 20 mbar for 2 h. This work focused on the optimization of the second step’s conditions, by varying reaction temperature (80–95 °C), pressure (20 mbar, 200 mbar) and reaction time (2 h, 6 h). Based on the optimization results, the process was scaled up (ca. 10 g of product). A PBS grade free of thermal degradation and metal catalyst residues, of weight-average molecular weight 4700 g/mol and melting point 103 °C, was obtained.

About the transformation of low Tm into high Tm poly(l-lactide)s by annealing under the influence of transesterification catalysts

Cyclic polylactides were prepared in bulk at 170 °C, crystallized at 120 °C and then annealed at temperatures between 130 and 170 °C with variation of catalyst, catalyst concentration and annealing time.

Biochars and Their Use as Transesterification Catalysts for Biodiesel Production: A Short Review

Biodiesel can be a significant alternative for diesel. Usually, it is produced through transesterification with a base catalyst. Using heterogeneous catalysts for transesterification, the process can be more efficient. Among the possible catalysts that can be used, biochars combine high performance for transesterification and valorization of waste biomass. Biochars are cheap materials, and are easy to activate through chemical treatment with acid or base solutions. In this short review, the application of biochar as solid heterogeneous catalysts for transesterification of lipids to produce biodiesel is discussed.

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

The use of ionic liquids (ILs) as organocatalysts is reviewed for transesterification reactions, specifically for the conversion of nontoxic compounds such as dialkyl carbonates to both linear mono-transesterification products or alkylene carbonates. An introductory survey compares pros and cons of classic catalysts based on both acidic and basic systems, to ionic liquids. Then, innovative green syntheses of task-specific ILs and their representative applications are introduced to detail the efficiency and highly selective outcome of ILs-catalyzed transesterification reactions. A mechanistic hypothesis is discussed by the concept of cooperative catalysis based on the dual (electrophilic/nucleophilic) activation of reactants.