Dielectric and thermal behaviors of POSS reinforced polyurethane based polybenzoxazine nanocomposites

POSS (polyhedral oligomeric silsesquioxane) reinforced polyurethane (PU) based polybenzoxazine (PBz) nanocomposites were prepared as an interlayer low k dielectric material for microelectronics applications based on the concept of polarization and porosity of the composite. The hydroxyl terminated benzoxazine (OH-Bz) materials containing a less polar long aliphatic chain and hydroxyl terminated nanoporous POSS (OH-POSS) material were synthesized and copolymerized with hexamethylenediisocyante (HMDI) to obtain POSS-Bz-PU nanocomposites. Dielectric analysis of different concentrations of POSS reinforced PU-PBz nanocomposites indicates that the incorporation of POSS into the polymer matrix significantly reduced the value of the dielectric constant. Despite this, the reduction of dielectric constant by reinforcement is limited up to 30% POSS-PU-PBz (k = 1.94) and beyond this concentration the reverse trend was observed which might be due to the increasing density of the resulting composites by agglomeration of POSS nanoparticles. The SEM images of 40% POSS-PU-PBz composites evidently support the agglomerate formation of POSS particles. Besides, the thermal stability of the resulting POSS reinforced PU-PBz nanocomposites also increased to an appreciable extent.