Ultra-low-κ materials derived from poly(D,L-lactide-b-pentafluorostyrene) diblock copolymers

Well-defined diblock copolymers of D,L-lactide and pentafluorostyrene with narrow molecular weight distributions (polydispersity index <1.25) were successfully synthesized via sequential ring-opening and atom transfer radical polymerizations. Poly(D,L-lactide) is the minority component; microphase separation results in discrete poly(D,L-lactide) nanostructures organized in a polypentafluorostyrene matrix. The poly(D,L-lactide) block was then quantitatively degraded and removed via acid-catalyzed hydrolysis to yield a nanoporous fluorinated matrix with the same lattice dimensions as those of the parent diblock copolymer. These nanoporous fluorinated films have overall dielectric constants <2.0, making them suitable candidates as interlayer metal insulators in microelectronic applications. Further, the dielectric constants of these films can be tuned by adjusting the amount of poly(D,L-lactide) in the parent diblock copolymers during synthesis.