Syntheses of multi-functional aromatic copolymers (PDVs) with controlled molecular architectures and development of novel low dielectric loss materials from PDVs.

Soluble poly(divinylbenzene-co-ethylstyrene-co-styrene)s (PDVs) are attractive materials as a curable resin to solving the subjects for the low dielectric loss materials in the field of electronic equipment for mobile appliances, high speed data networks. In spite of the importance of a soluble curable vinyl resin, the limited attempts of polymerization of multi-vinyl monomers have been reported. In order to synthesize PDVs with controlled molecular architectures, the copolymerization behaviors of divinylbenzene (DVB) ethylstyrene (EST) and styrene (ST) were investigated. The BenzCI/SnCU /THF initiating system afforded the PDVs with controlled molecular weights (ca. 1500-3500), narrow molecular weight distribution (ca. 2.0-3.0) and high amounts of pendant vinyl group (ca. 20- 80 mol%) in fairly good polymer yield (50-70 wt%). The NMR measurements and elemental analyses on the vinyl contents and terminal groups in PDVs elucidated that the PDVs have a highly branched structure. The obtained PDVs exhibited the good solvent solubility for the wide range of organic solvent (toluene, acetone, THF, and etc.). The PDVs based semi-interpenetrating polymer networks (semi-IPNs) were also investigated. The blends of PDVs, elastomers and heat resistant polymers showed a good miscibility, and afforded the highly flexible cured films with the high glass transition temperature (Tg : ca. 200degC). These PDVs based semi-IPNs ( DXK series as the trade name) were applied to the insulating electrical materials. The features of DXK series are low dielectric loss (dielectric constant: 2.4-2.6, dissipation factor : 0.002-0.004 at 10 GHz), high heat resistance (Tg : ca. 200degC), low moisture absorption (< 0.1 %), high tensile elongation ( > 10 - 30%), good processability. It has been of high expectation for DXK series toward high speed propagation and high packing density mounting for mobile appliances and high speed data networks.