High χ block copolymers based on chemical modification of poly(t-butyl acrylate) containing block copolymers

We report the synthesis and characterization of novel block copolymer (BCP) materials for the directed self-assembly (DSA) nanolithography applications. Specifically, the poly(t-butyl acrylate) (PtBA) block in the styrenic block copolymers have been chemically modified to a fluorinated block for the enhancement of the BCP χ-parameters. dPSb- PtBA had been first synthesized by anionic polymerization to prepare a well-defined BCP precursor with narrow polydispersity for the fluorination of PtBA block. Then, the precursor BCP was chemically modified by transalcoholysis of the PtBA-block with 2,2,2-trifluoroethanol. This strategy offers the advantage of flexibility and controllability to tailor the χ-parameter, while maintaining the narrow molecular weight distribution of the BCP materials for the advanced lithography applications. The transmission electron microscopy/small angle x-ray scattering (TEM/SAXS) characterization results of the modified BCP consisting of poly(fluoroalkylate) and PS supported the development of highly ordered lamellar domains in bulk.