Dicyclopentadiene-sourced cycloalkyl tetra-esters as eco-friendly plasticizers for PVC

Abstract

To address growing concerns regarding the endocrine-disrupting effects of traditional phthalate plasticizers (PAEs), this study synthesized three novel cycloalkyl tetra-ester compounds (1c, 2d, and 3d) as sustainable alternatives, utilizing readily available dicyclopentadiene (DCPD) as a precursor. PVC formulations incorporating 50 wt % of compound 3d exhibited enhanced tensile strengths (24.5 MPa) and improved thermal stability (T5% = 213.5 °C) compared to dioctyl phthalate (DOP; 22.2 MPa and 191.3 °C, respectively). The optimized molecular geometry suggests that the multi-cyclic and bridged structures, along with the four interlocked alkyl groups of the synthesized compounds, enhance their interactions with polymer chains, thereby increasing resistance to volatilization and ethanol extraction in PVC. However, these structural features also restrict the mobility of the polymer chains, resulting in reduced elongation and a higher glass transition temperature, particularly for the tricyclic compound 3d. All synthesized compounds displayed less than 5% of the estrogen receptor binding affinity of DOP, suggesting negligible endocrine-disrupting effects. These cost-effective, DCPD-derived compounds show promise as eco-friendly alternatives to PAEs, particularly in applications requiring stringent environmental and health standards, such as infant products and food packaging.