Thermo-crosslinkable molecular glasses towards the low k materials at high frequency

Two molecular glasses having allyl side chains and thermo-crosslinkable benzocyclobutene (BCB) groups have been successfully synthesized. These molecules display good solubility in common organic solvents and show a typical glass-forming behavior of having no melting point and keeping a complete amorphous state. The thermally cured molecular glasses exhibit low dielectric constant ( D k ) and dielectric loss ( D f ) at 10 GHz, as well as low water uptake (Wa) even when they are immersed in boiling water for 72 h. Among them, a fluoro-containing molecule exhibits the best properties, showing D k of 2.53, D f of 1.93 × 10 −3 and Wa of 0.19%, respectively, indicating that fluoro groups can efficiently improve the dielectric properties of the molecules. A controlling test indicates that the allyl side chains make the molecules possessing glass-forming properties. • Two thermo-crosslinkable molecular glasses have been successfully synthesized via the facile routes. • The molecular glasses display good solubility and film-forming ability. • Cured molecular glasses exhibit low dielectric constant and dielectric loss at a high frequency of 10 GHz.