The need for polymers for high-end applications, coupled with the desire to mimic nature’s macromolecular machinery fuels the development of innovative synthetic strategies every year. The recently acquired macromolecular-synthetic tools increase the precision and enable the synthesis of polymers with high control and low dispersity. However, regardless of the specificity, the polymerization behavior is highly dependent on the monomeric structure. This is particularly true for the ring-opening polymerization of lactones, in which the ring size and degree of substitution highly influence the polymer formation properties. In other words, there are two important factors to contemplate when considering the particular polymerization behavior of a specific monomer: catalytic specificity and thermodynamic equilibrium behavior. This perspective focuses on the latter and undertakes a holistic approach among the different lactones with regard to the equilibrium thermodynamic polymerization behavior and its relation to polymer synthesis. This is summarized in a monomeric overview diagram that acts as a presynthetic directional cursor for synthesizing highly specific macromolecules; the means by which monomer equilibrium conversion relates to starting temperature, concentration, ring size, degree of substitution, and its implications for polymerization behavior are discussed. These discussions emphasize the importance of considering not only the catalytic system but also the monomer size and structure relations to thermodynamic equilibrium behavior. The thermodynamic equilibrium behavior relation with a monomer structure offers an additional layer of complexity to our molecular toolbox and, if it is harnessed accordingly, enables a powerful route to both monomer formation and intentional macromolecular design.

An effective microwave-assisted process for recycling low-density polyethylene (LDPE) waste into value-added chemicals was developed. To achieve fast and effective oxidative degradation aimed at production of dicarboxylic acids, nitric acid was utilized as an oxidizing agent. Different conditions were evaluated, where recycling time and concentration of oxidizing agent were varied and the end products were characterized by FTIR, NMR, and HPLC. After just 1 h of microwave irradiation at 180 °C in relatively dilute nitric acid solution (0.1 g/mL), LDPE powder was totally degraded. This transformation led to few well-defined water-soluble products, mainly succinic, glutaric, and adipic acids, as well as smaller amounts of longer dicarboxylic acids, acetic acid, and propionic acid. The length of the obtained dicarboxylic acids could to some extent be tuned by adjusting the reaction time, temperature, and amount of oxidizing agent. Finally, the developed process was verified by recycling LDPE freezer bags as model LDPE waste. The freezer bags were converted mainly into dicarboxylic acids with a yield of 71%, and the carbon efficiency of the process was 37%. The developed method can, thus, contribute to a circular economy and offers new possibilities to increase the value of plastic waste.

A one-pot synthetic methodology for fabricating stimuli-responsive hemicellulose-based hydrogels was developed that consists of the in situ formation of magnetic iron oxide (Fe₃O₄) nanoparticles during the covalent cross-linking of O-acetyl-galactoglucomannan (AcGGM). The Fe₃O₄ nanoparticle content controlled the thermal stability, macrostructure, swelling behavior, and magnetization of the hybrid hydrogels. In addition, the magnetic field-responsive hemicellulose hydrogels (MFRHHs) exhibited excellent adsorption and controlled release profiles with bovine serum albumin (BSA) as the model drug. Therefore, the MFRHHs have great potential to be utilized in the biomedical field for tissue engineering applications, controlled drug delivery, and magnetically assisted bioseparation. Magnetic field-responsive hemicellulose hydrogels, prepared using a straightforward one-step process, expand the applications of biomass-derived polysaccharides by combining the renewability of hemicellulose and the magnetism of Fe₃O₄ nanoparticles.

The rate of degradation of large-scale synthesized polylactide (PLA) of industrial origin was compared with that of laboratory-scale synthesized poly(L-lactide) (PLLA) of similar molar mass. The structural discrepancy between the two material types resulted in a significant difference in degradation rate. Although the hydrolysis of industrial PLA was substantially faster than that of PLLA, the PLA material became less brittle and fragmented to a lesser extent during degradation. In addition, a comprehensive picture of the degradation of industrial PLA was obtained by subjecting different PLA materials to hydrolytic degradation at various temperatures and pH’s for up to 182 days. The surrounding environment had no effect on the degradation rate at physiological temperature, but the degradation was faster in water than in a phosphate buffer after prolonged degradation at temperatures above the T_g. The degree of crystallinity had a greater influence than the degradation environment on the rate of hydrolysis. For a future use of polylactide in applications where bulk plastics are generally used today, for example plastic packages, the appropriate PLA grade must be chosen based on the conditions prevailing in the degradation environment.