Abstract
Poly(phenylene oxide)s (PPOs) were synthesized by oxidative polymerization of 2,6-dimethylphenol (2,6-DMP) catalyzed by copper-amine complexes in the presence of oxygen gas. Reaction conditions were optimized using various amine-contained copper complexes and changing solvents, temperature, and reaction time. Obtained polymers were characterized by GPC and 1H NMR spectroscopy. Currently, the best condition was found for the polymerization using Cu-DBA (dibutylamine) as a catalyst in co-solvent system (Methanol and toluene = 9:1) at 30 ºC for 4 hours affording high regioregularity, yield (81%) with number-average molecular weight (Mn) of 3100. In addition to unmodified PPOs, functional PPOs were synthesized for polymer blend and electric application (printed circuit board). PPOs with allyl side chain (AllylPPO-SC) was obtained by adding 2,6-DMP and 2-allyl-6-methylphenol in oxidative polymerization in the presence of DBA at 30 oC for 4hr in 81% yield with Mn of 7000. On the other hand, PPOs with allyl chain on end group (AllylPPO-EG) were obtained by end-capping reaction of PPO in the presence of allyl chloride for 15 hours. The yield of AllylPPO-EG were reached to 86% with Mn of 8800. Finally PPOs with bihydroxide groups (BispPPO) were obtained by similar way of AllylPPO-SC at 30 oC for 7 hours in 56% yield with Mn of 6100. Thermal properties and morphology study of synthesized polymers were investigated by TGA, DSC, and SEM analyses. PPOs blend (with acrylonitrile-butadiene-styrene (ABS)) in various content of PPO were measured by tensile strength instrument. The best blend system for maintaining the high Tg (111.02 oC) and high tensile strength (408 kg/cm2) is ABS/PPO-3 (10 phr). Both of crosslinkable PPOs (AllylPPO-SC and BispPPO) which would be used in printed circuit board have low dielectric constant (Dk = 2.87and 2.87) and dielectric dissipation (Df = 0.0029 and 0.0052).