Dispersing Carbon Nanotubes in Aqueous Solutions by a Starlike Block Copolymer

Abstract

The ability of dispersing carbon nanotubes (CNTs) in aqueous solutions by a starlike amphiphilic block copolymer with PPO-PEO segments (AP432) was investigated in detail. For comparison, two commercially available linear amphiphilic block copolymers, Pluronics L64 and F127, were also selected. It was found that AP432 and F127 can get good CNT dispersions, while L64 was proved to be unable to disperse CNTs. AP432 with five branches could disperse CNTs efficiently at much lower concentrations compared with the linear F127, although it has a smaller molecular weight and shorter terminal EO groups. This indicated clearly that, once branched, copolymers would get a much better ability to disperse CNTs. Increasing concentration of AP432 or F127 would disperse more CNTs, but at high copolymer concentrations the aggregation of dispersed CNTs was observed, which may be related to the free micelles formed by AP432 or F127 around CNTs. Other influencing factors such as the mass ratio of CNTs to copolymers and sonication time and strength were also discussed. From the molecular dynamics simulation results, it can be found that copolymers with five branches can gain better steric repulsions between adjacent CNTs, which is consistent with the experimental results.

Thermo-responsive graphene dispersions by liquid phase exfoliation of graphite aided by an alkylated Percec monodendron

“…This trend continues when c1 was increased to 0.5 wt.% where the supernatant is almost colorless after stored for two weeks. Similar trend has been noticed previously in aqueous dispersions of carbon nanotubes (CNTs) stabilized by a branched amphiphilic copolymer [22], where the reason was ascribed to the depletion effect caused by the micelle formation at high polymer concentrations. Here, this explanation does not seem to apply as 1 only forms a clear solution in chlorobenzene.…”

“…For example, to get dispersions with cg of 0.1 or 0.128 mg mL −1 , up to 20 wt.% 1-phenyloctane or arachidic acid is needed [13], which is more than 133 times larger than 1 applied in current system. The high efficiency of 1 to exfoliate graphite can be ascribed to its branched structure, which creates a stronger affinity with the graphene surface and a better steric repulsion between neighbouring layers compared to its linear analogues [22].…”

Production of yellow-emitting carbon quantum dots from fullerene carbon soot

“…The two peaks at 1320-1340 (D band) and 1560-1590 cm −1 (G band) observed in the Raman spectra (Fig. 3a) correspond to the vibrations of carbon atoms with disordered carbon structure (sp 3 ) and sp 2 -bonded carbon atoms with a crystal lattice, respectively [41,42]. The intensity ratio of D and G bands (ID/IG), is normally used as a measure of the defect-density in carbon-rich materials.…”

Comparison of aggregation behaviors between branched and linear block polyethers: MesoDyn simulation study

“…Recently, we have explored the properties of branched block polyethers and compared with the linear triblock polyethers [35][36][37][38][39][40][41]. The results show that branched block polyether has many advantages in practical applications, such as in synthesis of nanoparticles [36], oil demulsification [37,38], and dispersing carbon nanotubes [39].…”

“…The results show that branched block polyether has many advantages in practical applications, such as in synthesis of nanoparticles [36], oil demulsification [37,38], and dispersing carbon nanotubes [39]. The aggregation behaviors of a branched block polyether (AP432) compared to the linear triblock polyether L64 at the air/water surface and in bulk aqueous solutions have been investigated [40,41].…”