Heterogenous mixed-molecular weight polymer brushes as neutral templates for block-copolymer orietation control.*

Distinctive polymer brushes play a crucial role in providing a neutral surface conducive for orientational control of block copolymers (BCPs). This bottom-up approach effectively align the formation of lamellar-like, cylinder, sphere, or gyroid structures of BCP thin films for use as nanopaterning templates. These templates modified for pattern transfer in applications such lithography, photovoltaics and membranes structures. In conventional BCP self-assembly techniques, random copolymers (RCPs) brushes are commonly employed to achieve substrate neutrality. However, these methods face significant drawbacks, including batch variations and lack of ability to tune surface energy during grafting. To address these issues, various approaches have been proposed to mitigate inconsistencies and enhance tunability, albeit with associated costs. Our proposition involves a system of polymer brushes composed of Polystyrene (PS) and Poly(methyl methacrylate) (PMMA) with mixed ratios, polymer chain lengths, and chemical enhancement. This system aims to effectively control surface energy combining the effects of chemistry and macromolecular structure, which offers a straightforward, low-cost template to serve as a tunable neutral brush for BCP self-assembly.