Chemical Synthesis and Environmental Characterization of Polyethylene Terephthalate Microplastics: A comprehensive Analysis of Degradation Mechanisms in the Red Sea Coastal Environment

This investigation elucidates the chemical mechanisms underlying both the synthesis and environmental degradation of polyethylene terephthalate (PET) microplastics in marine systems. Through controlled step-growth melt polymerization, PET were synthesized with precisely characterized molecular architecture (Mw = 45,000 g/mol, PDI = 2.43), enabling systematic comparison with environmental samples. The research employed multiple complementary analytical techniques (SEM-EDX, XRD, Raman, FTIR, AFM) to characterize both synthesized and 16 environmental samples collected from 5 distinct sites along the Red Sea coast of Jeddah, Saudi Arabia. Quantitative analysis revealed significant chemical transformations in environmental samples, including oxidative degradation (evidenced by O/C ratios ranging from 0.77 to ∞) and hydrolytic chain scission of ester linkages (confirmed by carbonyl index variations). Marine conditions (temperature: 32°C ± 0.5°C, pH: 8.50 ± 0.12, salinity: 39.59 ± 1.38 PSU) were found to accelerate polymer degradation through multiple mechanistic pathways. This research provides fundamental insights into the chemical lifecycle of PET microplastics in marine environments, contributing to the understanding of their environmental persistence and transformation mechanisms.