Stability of photocurable anhydrides: Methacrylic acid mixed anhydrides ofnontoxic diacids

Disproportionation of the liquid mixed anhydride dimethacrylic sebacic anhy dride (m-SA) to methacrylic anhydride and polyanhydride oligomers, as well as vinylic polymerization, can occur on workup and storage at room temperat ure. Dimethacrylic 1,3-bis(p-carboxyphenoxy) propane, being a solid, can al so disproportionate, but the propensity to do so is lower than for m-SA. Th ese events can be suppressed with free-radical inhibitors, and the inhibito r 2 + 3-t-butyl-4-methoxyphenol is a more effective stabilizer than 4-metho xyphenol at 20.degreesC. (C) 2001 John Wiley & Sons, Inc.