Influence of Haloacetic Acid Type and Chain Length on Catalyst‐Assisted Esterification of Polyethylene Glycols

ABSTRACT Biocompatible and water‐soluble polyethylene glycol (PEG) undergoes esterification with carboxylic acid derivatives, enabling the synthesis of functional materials for pharmaceuticals, controlled‐release systems, and textile modifications. Haloacetic acid derivatives are preferred due to their strong electron‐withdrawing properties and high reactivity. The resulting ester structures exhibit varying chemical and physical properties depending on the halogen used. Parameters such as the electronegativity, polarizability, and molecular volume of chlorine and bromine atoms provide essential insights into esterification kinetics and product behavior. In this study, esterification reactions between PEGs of different chain lengths (PEG 200, 300, and 400) and chloroacetic acid (ClCH 2 COOH) and bromoacetic acid (BrCH 2 COOH) were comparatively investigated. The reactions were carried out at various temperatures, and product conversion rates were monitored over time. The products were characterized using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy to observe changes in the ester carbonyl and PEG chain. Based on the experimental data, the effects of halogen type and PEG chain length on reaction kinetics and product formation were systematically evaluated. Additionally, the thermal properties were examined via thermogravimetric analysis (TGA). This study characterizes PEG‐based chloroesters (PEG n ClEs) and bromoesters (PEG n BrEs), providing a comprehensive evaluation of their synthesis and temporal variations.