Synthesis and Performance of Epoxy-Terminated Hyperbranched Polymers Based on Epoxidized Soybean Oil

Epoxy-terminated hyperbranched polymers (EHBPs) are a class of macromolecular polymers with a hyperbranched structure containing epoxy groups. They possess characteristics such as low viscosity, high functionality, and thermal stability, which endow them with broad application potential in materials science and chemical engineering. This study uses epoxidized soybean oil (ESO) as the raw material, which undergoes ring-opening reactions with glycerol and is esterified with 2,2-bis(hydroxymethyl)propionic acid (DMPA) to obtain epoxy soybean oil polyol (EGD) with a high hydroxyl value. Subsequently, four types of EHBPs are synthesized by incorporating epichlorohydrin (ECH) in mass ratios of 1:3, 1:4, 1:5, and 1:6 under strong alkaline conditions. The product structure is characterized using FT-IR and GPC. The degree of branching of EGD is calculated using ¹H NMR and ¹³C NMR spectroscopy. The epoxy value of EHBPs is tested using the hydrochloric acid-acetone method, and the water contact angle, adhesion properties, rheological properties, and thermal properties of the EHBPs are also evaluated. The results show that the degree of branching of EGD is 0.45. The epoxy values of the EHBPs are 0.73, 0.79, 0.82, and 0.89 mol/100g, respectively. As the epoxy value and molecular weight of the epoxy hyperbranched polymers (EHBPs) increase, the water contact angle and adhesion strength of the EHBPs rise progressively and the viscosity decreases. Additionally, the glass transition temperature increases with the increase in the epoxy value. These epoxy hyperbranched polymers with low viscosity and high adhesion strength offer a promising approach for modifying surface coatings or formulating adhesives.