Depleting depletion: maintaining single-walled carbon nanotube dispersions after graft-to polymer functionalization
Author(s)
Type
Journal Article
Abstract
Grafting polymers onto single-walled carbon nanotubes (SWCNTs) usefully alters properties but does not typically yield stable, solvated species directly. Despite the expectation of steric stabilization, a damaging (re)dispersion step is usually necessary. Here, poly(vinyl acetate)s (PVAc) of varying molecular weights are grafted to individualized, reduced SWCNTs at different concentrations to examine the extent of reaction and degree of solvation. The use of higher polymer concentrations leads to an increase in grafting ratio (weight fraction of grafted polymer relative to the SWCNT framework), approaching the limit of random sequentially adsorbed Flory ‘mushrooms’ on the surface. However, at higher polymer concentrations, a larger percentage of SWCNTs precipitate during the reaction; an effect which is more significant for larger weight polymers. The precipitation is attributed to depletion interactions generated by ungrafted homopolymer overcoming Coulombic repulsion of adjacent like-charged SWCNTs; a simple model is proposed. Larger polymers and greater degrees of functionalization favor stable solvation, but larger and more concentrated homopolymers increase depletion aggregation. By using low concentrations (25 μM) of larger molecular weight PVAc (10 kDa), up to 65% of grafted SWCNTs were retained in solution (at 65 μg mL-1) directly after the reaction.
Date Issued
2018-12-18
Date Acceptance
2018-11-12
Citation
Langmuir, 2018, 34 (50), pp.15396-15402
ISSN
0743-7463
Publisher
American Chemical Society
Start Page
15396
End Page
15402
Journal / Book Title
Langmuir
Volume
34
Issue
50
Copyright Statement
© 2018 American Chemical Society
Sponsor
Engineering & Physical Science Research Council (E
Engineering & Physical Science Research Council (EPSRC)
Grant Number
AERO/RB1527
N/A
Subjects
Science & Technology
Physical Sciences
Technology
Chemistry, Multidisciplinary
Chemistry, Physical
Materials Science, Multidisciplinary
Chemistry
Materials Science
REDUCTIVE DISSOLUTION
MECHANICAL-PROPERTIES
MD Multidisciplinary
Chemical Physics
Publication Status
Published
Date Publish Online
2018-11-14