The role of steric interactions in dispersion of carbon nanotubes by poly(3-alkyl thiophenes) in organic solvents.
The dispersion mechanism of carbon nanotubes (CNTs) in organic solutions of poly(3-alkyl thiophenes, P3ATs) was examined in a study that combines experimental investigation of the dispersion mechanism and molecular theory calculations of the effective intertube potential for polymer wrapped CNTs. The minimal polymer concentration required for dispersion of CNT served as a comparative measure of the efficiency of P3AT derivatives that differ in the length of the alkyl side chains or the regiochemistry of the monomers in three solvents: 1,2 and 1,3 dichlorobenzene and chloroform. While previous studies focused on the adsorption mechanism of P3ATs onto SWNT, we find that the dispersing efficiency depends not only on the stacking of the polymer backbone onto the CNT ("wrapping"), but also on the steric repulsion among the side chains of adsorbed P3ATs. In accordance with the experiments, our calculations indicate that high surface density of polymers with longer side chains and large tube diameter promote the formation of stable dispersions of relatively high loadings of CNTs, at low polymer:CNT ratios.
Dept. of Chemical Engineering, The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Avraham
A
Bar-Hen
Dept. of Chemical Engineering, The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Céline
C
Bounioux
Dept. of Chemical Engineering, The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel. Electronic address: rachely@bgu.ac.il.
Rachel
R
Yerushalmi-Rozen
Department of Biomedical Engineering, Department of Chemistry and Chemistry of Life Processes Institute, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, United States.
Estefania
E
Gonzalez Solveyra
Department of Biomedical Engineering, Department of Chemistry and Chemistry of Life Processes Institute, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, United States.
Igal
I
Szleifer
D002722:Chlorobenzenes / Q000737:chemistry; D002725:Chloroform / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D011108:Polymers / Q000737:chemistry*; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D013499:Surface Properties; D013876:Thiophenes / Q000737:chemistry*
D002722:Chlorobenzenes; D037742:Nanotubes, Carbon; D011108:Polymers; D012996:Solutions; D012997:Solvents; D013876:Thiophenes; C004726:2-dichlorobenzene; C042146:1,3-dichlorobenzene; D002725:Chloroform
Carbon nanotubes; Conjugated polymers; Dispersions; Pi–pi conjugation; Polythiophenes; Steric stabilization; Wrapping