The Effect of Vacuum Drying vs. Ambient Drying on the Nanostructural, Mechanical, and Rheological Properties of PEGDA Hydrogels

Abstract

Drying is a critical yet often overlooked step in the synthesis of poly(ethylene glycol) diacrylate (PEGDA), as it governs solvent removal, polymer chain organization, and ultimately the structural and mechanical properties of the resulting hydrogel. In this study, PEGDA was synthesized through an acrylation reaction, purified via sequential washing and filtration, and subsequently subjected to two distinct drying methods: ambient drying and vacuum drying at 35 °C. The dried PEGDA powders were then photo-crosslinked using IRGACURE 1173 to form hydrogels for comparative analysis. Results revealed that the vacuum-dried PEGDA exhibited superior structural uniformity and mechanical strength, producing nanoparticles with an average diameter of 4.6 nm as measured by DLS. The corresponding hydrogel displayed a Young’s modulus of 7.1 kPa, nearly double that of the ambient-dried sample (3.9 kPa). Rheological analysis further confirmed a fourfold increase in crossover stress (G′ = G″) for vacuum-dried PEGDA (34.5 kPa) compared to the ambient-dried counterpart (8.7 kPa), signifying enhanced elasticity and network integrity. These findings highlight that controlled vacuum drying significantly improves polymer uniformity and crosslinking efficiency, providing a simple yet effective strategy for optimizing PEGDA hydrogels in advanced applications such as solar vapor generation and water purification.