Effect of Solvents\non the Performance and Structure\nof Polymethylacrylimide Aerogels

Solvent effects play a critical role in solution polymerization,\nespecially in free radical polymerization, where they influence both\nmonomer–solvent interactions and the resulting polymer structure.\nIn this study, polymethacrylimide (PMI) aerogels were synthesized\nvia freeze-drying using dimethylformamide (DMF), dimethylacetamide\n(DMAc), and dimethyl sulfoxide (DMSO) as solvents. The effects of\nmonomer reactivity ratios, monomer distribution, and solvent–monomer\ninteractions on the shrinkage, bulk density, pore size, and compressive\nproperties of the aerogels were investigated. Results demonstrated\nthat solvent choice significantly impacted the polymerization process,\nleading to variations in the structure and properties of the final\naerogels. Notably, aerogels synthesized in DMSO, the most polar solvent,\nexhibited the lowest shrinkage (33.98%), highest density (0.1582 g·cm<sup>–3</sup>), and highest compressive stress (1695.48 kPa at\n70% strain). These findings underscore the importance of solvent selection\nin controlling the microstructure and enhancing the mechanical performance\nof PMI aerogels.