Highly Aligned Carbon Nanowire Array by E-Field Directed Assembly of PAN-Containing Block Copolymers

Abstract

Nanoscale engineering of carbon materials is immensely demanded in various scientific areas. We present highly ordered nitrogendoped carbon nanowire arrays via block copolymer (BCP) self-assembly under an electric field. Large dielectric constant difference between distinct polymer blocks offers rapid alignment of PMMA-b-PAN self-assembled nanodomains under an electric field. Lithographic patterning of the graphene electrode as well as straightforward thermal carbonization of the PAN block creates well-aligned carbon nanowire device structures. Diverse carbon nanopatterns including radial and curved arrays can be readily assembled by the modification of electrode shapes. Our carbon nanopatterns bear a nitrogen content over 26%, highly desirable for NO 2 sensing, as the nitrogen element acts as adsorption sites for NO 2 molecules. Aligned carbon nanowire arrays exhibits a 6-fold enhancement of NO 2 sensitivity from a randomly aligned counterpart. Taking advantage of well-established benefits from deviceoriented BCP nanopatterning, our approach proposes a viable route to highly ordered carbon nanostructures compatible to next-generation device architectures.

Block Copolymer Nanopatterning for Nonsemiconductor Device Applications

“…In addition, because of the growing concerns for environmental pollution and epidemics, novel sensing mechanisms are demanded to detect the hidden symptoms in a living system. Accordingly, various sensing systems are under active investigations nowadays to effectively monitor biomolecules, toxic chemicals, pollutants, ,, and other external environments (e.g., temperature and humidity). For the realization of such high-performance sensors, nanomaterials can be useful because of their inborn large surface-to-volume ratio and high surface activity clearly differentiated from bulk type counterparts. , A high surface-to-volume ratio is particularly significant, since most sensor systems rely on the surface reactions in their sensing mechanisms …”

“…Furthermore, the conductive nanochannels created by BCP nanopatterning can be used for gas sensors. Recently, Han et al demonstrated NO 2 gas sensors by exploiting N-doped carbon nanowire arrays prepared from the direct carbonization of self-assembled BCP nanopatterns . Wei et al showed NH 3 gas sensors using electroconductive poly­(3-hexylthiophene) (P3HT) nanowire arrays produced from the self-assembly of P3HT containing BCPs .…”

“…BCP nanopatterning can also be utilized for the various other types of sensors, such as electrochemical sensors ,, and biosensors. , As a representative electrochemical sensor, a dopamine sensor has been introduced for the detection of neurological disorders. Dopamine commonly coexists with other chemicals in vivo, so that the development of high-sensitivity dopamine selective sensors is highly challenging.…”

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Electric Field Assist on Enhancing the Electrical Breakdown Strength of Cross-Linked Polyethylene for Power Cable Insulation

“…Furthermore, the electric field assist is viable to regulate the morphology of polymers, − and has often been applied to control the structural parameters of the nanostructured block copolymers on both mesoscopic and nanoscopic length scales. − Tashiro et al found that the assisted electric filed (>±15 MV/m) applied to the poly­(vinylidene fluoride) (PVDF) leads to the transformation from β low‑E phase into the β high‑E phase . Sugita et al reported that the poly­( l -lactic acid) (PLLA) forms at the edge of the anode under the assisted electric field and grows in the direction parallel to the electric field, which is important to enhance the mechanical and thermal properties .…”