Catalyst-free synthesis of phosphinated poly(2,6-dimethyl-1,4-phenylene oxide) with high-T sub(g) and low-dielectric characteristic

Phosphinated poly(2,6-dimethyl-l,4-phenylene oxide) (5-7) with various phosphorus contents were prepared through the bromination of poly(2,6-dimethyl-l,4-phenylene oxide) (PPO), followed by a catalyst-free nucleophilic substitution of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO) on the resulting benzyl bromide of brominated PPO (2-4). Phosphinated PPOs showed improved solubility when compared with neat PPO. A phosphinated PPO with a T sub(g) at 227 [degrees]C (DMA data), T sub(d) 5% at 452 [degrees]C (N sub(2)) and 473 [degrees]C (air), low moisture absorption (0.7 wt% in boiling water, 48 h), a dielectric constant of 2.82 (1 GHz), and a UL-94 VTM-0 grade can be achieved with a phosphorus content as low as 1.0 wt%. Via this approach, the solubility and flame retardancy of PPO were enhanced while the thermal and dielectric properties were kept.