High-Resolution Nanopatterning of Free-Standing, Self-Supported Helical Polypeptide Rod Brushes via Electron Beam Lithography

Abstract

In this study of nanopatterned helical poly­(benzyl-l-glutamate) (PBLG) brushes, rod-type brush arrays were fabricated via an integrated process of high-resolution lithography and surface-initiated vapor deposition polymerization (SI-VDP). “Nanospikes” of polymer brushes with spacings of less than 100 nm were produced. The topology and areal behavior of the resulting patterned rod-like brushes were analyzed and compared with patterned coil-type brushes. A geometric study of these self-assembled “nanospikes” was carried out, and their cross sections were investigated via focused ion beam (FIB) and scanning electron microscopy (SEM). Furthermore, the presence of poly­(N-isopropylacrylamide) (PNIPAM) brushes in unpatterned regions was shown to inhibit undesired “inter-spike” bridging of the PBLG brushes, resulting in more well-defined nanostructures. It was shown that rod-like polypeptide brushes are capable of self-segregation and become arranged vertically without any external support from their surroundings, to form a rod bundle end-point functional topography that could provide possible pathways for studies of model biological surfaces, directed assembly of nanoparticles, or binary mixed brush surfaces with dual properties.

Advancing Glucose Sensing Through Auto‐Fluorescent Polymer Brushes: From Surface Design to Nano‐Arrays

“…Nanopatterned polymer brushes were prepared through a “bottom–up” approach using a sequence of electron beam lithography (EBL) and surface‐initiated radical polymerization according to a previously reported procedure, [ 39 ] where patterns of surface‐immobilized azo‐initiator were prepared and used as templates to grow the brushes. ( Scheme ) Synthesis from the nanopatterned substrates was carried out following the same procedure as for the unstructured films which resulted in brushes with well‐defined features and varying dimensions ranging from 60 to 270 nm.…”

“…Preparation of Patterned Substrates: Patterned substrates were prepared according to a previously reposted procedure. [39] E-beam resist was patterned via JEOL 9500, which was later used as the mask for the vapor deposition of the silane coupling agent. Prior to the deposition, the substrate was descummed via the Oxford 81 etcher to remove residual debris in the unmasked area.…”

“…[ 38 ] Huang et al. [ 39 ] have developed a mixed rod‐coil brush system with poly(N‐isopropylacrylamide) (PNIPAM)/poly(γ‐benzyl‐l‐glutamate) and shown that more well‐defined end‐point functional nanospikes can be achieved by incorporating secondary brushes into the system. Zhao et al.…”

“…Furthermore, the integration of different polymer brush types in a single system allows for the creation of multifunctional surfaces. [38] Huang et al [39] have developed a mixed rod-coil brush system with poly(N-isopropylacrylamide) (PNIPAM)/poly(𝛾-benzyll-glutamate) and shown that more well-defined end-point functional nanospikes can be achieved by incorporating secondary brushes into the system. Zhao et al [40] have reported successful fabrication of multiplexed brush architectures and reported the precise regulation of biomolecule immobilization using poly (glycidyl methacrylate)/poly(2-(2-azido-2-methyl-1-oxopropoxy) ethyl methacrylate) brush-based patterned surfaces.…”