Fabrication routes for one-dimensional nanostructures via block copolymers

Abstract

Nanotechnology is the field which deals with fabrication of materials with dimensions in the nanometer range by manipulating atoms and molecules. Various synthesis routes exist for the one, two and three dimensional nanostructures. Recent advancements in nanotechnology have enabled the usage of block copolymers for the synthesis of such nanostructures. Block copolymers are versatile polymers with unique properties and come in many types and shapes. Their properties are highly dependent on the blocks of the copolymers, thus allowing easy tunability of its properties. This review briefly focusses on the use of block copolymers for synthesizing one-dimensional nanostructures especially nanowires, nanorods, nanoribbons and nanofibers. Template based, lithographic, and solution based approaches are common approaches in the synthesis of nanowires, nanorods, nanoribbons, and nanofibers. Synthesis of metal, metal oxides, metal oxalates, polymer, and graphene one dimensional nanostructures using block copolymers have been discussed as well.

Keywords: Block copolymer; Nanofiber; Nanorod; Nanotechnology; Nanowire.

Fig. 1

Approaches for synthesis of nanostructures [2]

Fig. 2

Types of block copolymers

Fig. 3

Polymerisation methods for the synthesis of block copolymers

Fig. 4

Types of nanowires

Fig. 5

a Low magnification SEM images of Mn₃O₄ nanostructures/nanowires. b, c High magnification SEM images of Mn₃O₄ nanostructures/nanowires [41]

Fig. 6

SEM images of silicon nanowires. a With AR of 30, b with AR of 200 [53]

Fig. 7

a TEM images of gold nanowires, b inset shows high resolution image of gold nanowires [55]

Fig. 8

a, b TEM images of Cu₂O nanowires [56]

Fig. 9

a–c FE-SEM images of ZnO nanorods grown from different templates. The yellow schematic images show the pore size of each template. Inset images show the side view and the flexible substrate held by tweezers [58]

Fig. 10

FE-SEM images of nanoporous templates prepared by the block copolymer mixture film on the ITO glass and polypyrrole nanorods. a, b Top and cross-sectional images of the nanoporous template. c, d Top and cross-sectional images of polypyrrole nanorods after removing the template [60]

Fig. 11

TEM cross-sectional image of Si nanorods. a Underlying Si wafer connected with Si₃N₄ nanodots, b Si nanorods connected to underlying Si wafer after etching of the exposed Si [61]

Fig. 12

SEM image of GNR array. Inset GNR under high magnification with nanoribbon width around 8 nm [67]

Fig. 13

TEM image of diblock nanofibers [71]