Studies on photocrosslinkable-cum-flame retardant poly(benzylidene phosphoramide ester)s

Four series of photocrosslinkable-cum-flame retardant poly(benzylidene phos phoramide ester)s were synthesized from bis(4-hydroxy-3-methyoxybenzylidene ) acetone, 2,5-bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone 2,6-bis(4- hydroxy-3-methoxybenzylidene)cyclohexanone and 2,7-bis(4-hydroxy-3-methoxyb enzylidene) cycloheptanone with various arylphosphorodichloridates by inter facial polycondensation using a phase transfer catalyst. The resultant poly mers were characterized by gpc, FTIR, H-1, C-13 and P-31-NMR spectroscopy. Thermal behavior of the polymers was evaluated by differential scanning cal orimetry and thermogravimetry. Flame retardant properties were ascertained by Limiting Oxygen Index. The photocrosslinking ability of the polymers was studied by ultraviolet spectroscopy. The crosslinking proceeds via 2 pi 2 pi cycloaddition reaction of the benzylidene groups. The rate of crosslin king decreases with increase in the size of cycloalkanone ring, while the t hermal stability increases with increase in the size of the alkanone ring. (C) 1999 John Wiley & Sons, Inc.