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The development of more sustainable materials from renewable resources has increasingly gained attention. In this work, commercial limonene oxide was used as a monomer to obtain polyesters with phthalic and maleic anhydrides. The ionic liquid 1-n-butyl-3-methylimidazolium heptachlorodiferrate (BMI·Fe2Cl7) was the catalyst for ring-opening polymerization. For both cyclic anhydrides, conversions around 80% were reached with a 1:100 catalyst:limonene oxide molar ratio. The resulting polymers presented a perfectly alternating structure, number-average molar mass over 1000 g mol−1, and pendant double-bonds that allow subsequent modification of their structures. Regarding their application, such as nanodevices for biological systems, poly(phthalic anhydride-co-limonene oxide) (PPALO) nanoparticles (NPs) were also produced and cross-linked with tetrathiol via thiol-ene reaction. The cross-linked PPALO-NPs with a number-weighted mean diameter of 56 nm, spherical morphology, and good colloidal stability were obtained. These NPs were tested for blood compatibility with human red blood (erythrocytes) cells and cell viability using mouse embryo fibroblast (NIH3T3) cell line, presenting potential for biomedical applications. [ABSTRACT FROM AUTHOR]

Polycaprolactone is a biodegradable, biocompatible, and versatile polymer commonly used in the pharmaceutical and biomedical industry and the development of new catalysts that allow for the synthesis under milder reaction conditions and in shorter reaction times is an appealing alternative. The iron-containing imidazolium-based ionic liquid 1-n-butyl-3-methylimidazolium heptachlorodiferrate was able to efficiently catalyze the ring-opening polymerization of ε-caprolactone under mild reaction conditions. Polymerization yields higher than 80% were obtained after 4 h of reaction at temperatures up to 85 °C, using low ionic liquid:ε-caprolactone molar ratios (1:720 − 1:1500), in the absence of solvent and without an intentionally added alcohol as an initiator. Semi-crystalline polycaprolactones, with molecular weights up to 14 kDa and narrow molecular weight distributions were synthesized. The chemical structure of the polymer was confirmed by Nuclear Magnetic Resonance (1H NMR) and Fourier Transform Infrared (FTIR) spectroscopy, and its crystalline content was estimated from the enthalpy of melting of the differential scanning calorimetry (DSC) thermogram. Finally, a caprolactone-activated ROP mechanism mediated by the ionic liquid was suggested. [ABSTRACT FROM AUTHOR]