Degradation of 10-methacryloyloxydecyl dihydrogen phosphate.

To understand the mechanism of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) hydrolysis, we investigated the degradation of 2-methacryloyloxyethyl dihydrogen phosphate (MEP), because the MEP molecule has the methacryloxy and phosphate ester portions of MDP but, unlike the latter, is water-soluble. The MEP-N-methcryloyl glycine (NMGly), MDP-NMGly, and MDP-2-hydroxyethyl methacrylate (HEMA) primers were designed, stored for different periods, and then analyzed. Our null hypotheses were that (1) the mechanism of MDP hydrolysis differs from that of MEP and (2) the type of hydrophilic monomer--NMGly or HEMA--has no effect on the MDP hydrolysis rate. Similar to the production of methacrylic acid (MA) and 2-hydroxyethyl dihydrogen phosphate (HEP) during MEP hydrolysis, MDP produced MA and 10-hydroxydecyl dihydrogen phosphate (HDP) during hydrolysis. However, the rate of MDP hydrolysis depended on the type of hydrophilic monomer: Compared with HEMA, NMGly significantly increased the rate of MDP hydrolysis.