Tailoring Triblock Copolymers for Dispersion of Individual, Pristine, Single-Walled Carbon Nanotubes in Organic Solvents

Abstract

Triblock copolymers, polyethylene oxide-(hexa-p-phenylene)-polyethylene oxide, were synthesized and used for dispersing single-walled carbon nanotubes (SWNT) in organic solvents. The resulting dispersions comprise mostly of individual tubes, as indicated by transmission electron microscopy at cryogenic temperatures. The dispersions could be dried and redispersed by the addition of a solvent, offering a useful method of application of predispersed SWNT. In situ optical spectroscopy indicates that the block copolymers which self-assemble in the native solution physically adsorb to the SWNT surface via the hexa-p-phenylene moiety. The noncovalent, weak adsorption competes with the polymer self-assembly, as clearly indicated by the emission spectra. The balance between self-assembly and adsorption is sensitive to the length of ethylene oxide side chains. The approach presented here may serve for optimization of the structure and composition of polymeric dispersants where one can chose between a long tail and a long adsorbing moiety, according to the specific needs presented by different applications of SWNT.

Non-covalent and reversible functionalization of carbon nanotubes

“…Nevertheless, the prevailing effect among the two is still under investigation. Polyethylene glycol (PEG) chains with PEG repeating units as long as 8, have been demonstrated [ 52 ] to favor both self-assembly and dispersion of SWCNTs in chloroform and 1,2-dichlorobenzene once chosen a hydrophobic domain B (i.e., hexa- p -phenylene) able to establish π–π interactions with the B block of another monomer or with the SWCNT surface, respectively. On the other hand, the capability of polystyrene- b -polyisoprene (PS- b -PI) diblock copolymers to disperse MWCNTs seems to be dominated by the solvent selectivity of the block copolymers, being the direct interaction between the nanotubes and the polymers of secondary importance [ 53 ].…”

Conjugated polymers ‐ carbon nanotubes‐based functional materials for organic photovoltaics: a critical review

“…It was shown that tri‐block copolymers that contain a middle block comprising a conjugated polymer and two non‐conjugated tails (for example ref …”

“…At this inter‐tube separation, the attractive interaction between adjacent tubes is much smaller than k B T (see Fig. (d)), and thus the weak‐long ranged repulsion prevents aggregation of the individually dispersed tubes …”

Reactive Multidentate Block Copolymer Stabilization to Carbon Nanotubes for Thermoreversible Cross-Linked Network Gels

“…The furfuryl groups are designed to react with maleimide groups in polymaleimides through a Diels–Alder (DA) reaction to form thermally labile cross-linked networks, − while the pyrene groups physically anchor to the surface of carbon materials through π–π interactions. − As a proof-of-concept, multiwalled carbon nanotubes (CNTs) were chosen as a model nanomaterial to investigate our rMDBC stabilization strategy. CNTs have outstanding optical, electrical, and thermal properties. − The synthesis and use of MDBCs with pendant aromatic moieties to disperse carbon materials, including CNTs, in solutions have been described in several reports; − however, the rMDBC stabilization of CNT surfaces is rarely explored. As illustrated in Figure , the rMDBC enabled the stabilization of CNT surfaces to form colloidally stable rMDBC/CNT colloids.…”