Water-soluble macromers based on 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (Na-AMPS) for rapid in situ hydrogel film formation

The in situ formation of hydrogels has potential for a number of biomedical applications but their generation via conventional polymerization techniques has a number of limitations, such as toxicity and reaction time. The use of macromers in hydrogel formulations can help overcome these limitations. In this work, we synthesized a new functionalized macromer formed via the copolymerization of 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS) and acid-functional monomers that can undergo a ring-opening reaction with allyl glycidyl ether (AGE) to generate the desired pendant vinyl macromer functionality. These macromers were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and gel permeation chromatography (GPC) to provide evidence for successful macromer synthesis and subsequent polymerization. Using a UV-initiated crosslinking approach with poly(ethylene glycol) diacrylate (PEGDA), the hydrogels were fabricated from the macromer solution, with the gelation time being reduced from 1200 s to 10 s when compared to hydrogel formation from regular vinyl monomers. While different acidic monomers result in distinct tensile properties, hydrogels containing 2-carboxyethyl acrylate (CEA) exhibit low strength but high elongation. In contrast, those with methacrylic acid (MAA) demonstrate higher strength and lower elongation. Therefore, using a balanced combination of each is a logical approach for achieving a robust final hydrogel film. In summary, we have produced a new macromer possessing characteristics highly conducive to rapid hydrogel synthesis. This macromer approach holds potential for use in in situ hydrogel formation, where a viscous solution can be applied to the target area and subsequently hardened to its hydrogel. We envisage its application primarily in the biomedical field.