Synthesis of new phosphorus-containing oligoester methacrylates by using aliphatic and aromatic spacers

A novel phosphorus-containing oligoester methacrylates (FOEMs) incorporating aliphatic and aromatic spacers were successfully synthesized in two stages. At the first stage, a diester-containing intermediate was produced by allowing phosphorus oxychloride to react with glycidyl methacrylate (GMA), subsequently, at the second stage the diester intermediate was added to diepoxide resins (E-181 and ED-20). The structures of oligoester methacrylates (OEMs) have been investigated intensively by using FTIR, GC/MS, STA, NMR and epoxy number (epoxide group content), where the outcomes revealed that the disappearance of epoxy groups was completely achieved, which is a result of the oxirane ring-opening reaction and the appearance of ester groups. The results confirmed the successful synthesis of FOEMs and were consistent with their predicted chemical structures. The obtained FOEMs showed excellent curing ability by free radical polymerization mechanism under conditions of both UV and thermal peroxide initiation. Polymerization processes were analyzed by using differential scanning calorimetry (DSC) and changes in dielectric analysis (DEA). The DSC results indicate that the presence and structure of the spacer influence on curing rate as well as on thermal effects of both initiation methods. DEA studies established that the blending of aliphatic spacer into the oligomer structure has little effect on photocuring rate, but the aromatic spacer increases the curing rate compared with FOEM without a spacer.