Síntese de polímeros policaprolactona empregando D-Limoneno como biossolvente

Abstract

A chemical reaction is a process in which some substances (the reactants) combine with each other to give rise to new reaction products. A promising alternative to replace traditional solvents, many of which are toxic and polluting, is the use of biosolvents, which are solvents from natural sources. The waste that would be discarded from the processing of oranges makes it possible to obtain an essential oil and its main component, D-Limonene, which is considered a low-toxicity molecule for society, which can be used as a biosolvent. Ring-opening polymerization (ROP) is an important process for the synthesis of polymers, especially those based on lactides and ε-caprolactone (ε-CL). The main purpose of this work was to evaluate the application of D-limonene as a biosolvent in ROP polymerization reactions. A total of 22 syntheses were carried out during the study. The reactions took place in the Chemistry laboratory of the Federal University of Pampa (UNIPAMPA), Itaqui Campus, following a ROP protocol that has been widely documented in the scientific literature. Hydrogen nuclear magnetic resonance (¹H NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) analyses were carried out. Although promising, the use of D-Limonene presented some limitations in terms of conversion to polycaprolactone. In ¹H NMR analyses, conversion values ranged from 11% to 28%, while DSC analyses revealed a low crystallization temperature, varying between 19.15° C and 20.06° C and a melting point of 38.47° C for A19 and 43.08° C for A21, which can be explained by the low conversion achieved, indicating a graft copolymer. In GPC, the dispersity of 1.16 is considered an excellent result, as it proves the control of the reaction. The values found in the toluene synthesis, shown as a solvent counter-proof, indicate that D-Limonene does not act negatively on the polymerization process and that adjustments can improve the efficiency of the syntheses. Finally, the use of methodological standards in ¹H NMR analysis and new syntheses with different initiators and catalysts are suggested.