Synthesis of a novel ris-spiroorthoester containing 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide as a substituent:: Homopolymerization and copolymerization with diglycidyl ether of bisphenol A

A :new bis-spiroorthoester-containing monomer, bis[(1,4,6-trioxaspiro-[4.4]-nonan-2-yl)-methyl] 2-[10-(9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide-10-yl)] maleate (SOE-DOPOMA), was synthesized with good yields by an esterification reaction with a hydroxylated spiroorthoester (2-hydroxymethyl-1,4,6-trioxaspiro-[4.4]-nonane) and a phosphorus-containing diacid {2-[10-(9,10-dihydri)-9-oxa-10-phosphaphenantrene-10oxide-10-yl)] maleic acid), both of which were previously synthesized. SOE-DOPOMA was characterized with H-1, C-13, and P-31 NMR spectroscopy. This new spiroorthoester was crosslinked with ytterbium triflate as a cationic initiator. A mixture of SOE-DOPOMA and diglycidyl ether of bisphenol A was also crosslinked under the same conditions. The curing was studied with differential scanning calorimetry and monitored with Fourier transform infrared spectroscopy. The materials were characterized with differential scanning calorimetry, thermogravimetric analysis, and thermodynamomechanical analysis. The shrinkage effect on cationic crosslinking was assessed with gas pycnometry, and the flame-retardant properties were determined with limiting oxygen index measurements. (c) 2006 Wiley Periodicals, Inc.