Depleting depletion: maintaining single-walled carbon nanotube dispersions after graft-to polymer functionalization

Title: Depleting depletion: maintaining single-walled carbon nanotube dispersions after graft-to polymer functionalization
Authors: Clancy, AJ
Leese, HS
Rubio Carrero, N
Buckley, DJ
Greenfield, JL
Shaffer, MSP
Item 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.
Issue Date: 18-Dec-2018
Date of Acceptance: 12-Nov-2018
URI: http://hdl.handle.net/10044/1/66368
DOI: https://dx.doi.org/10.1021/acs.langmuir.8b03144
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/Funder: Engineering & Physical Science Research Council (E
Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: AERO/RB1527
Keywords: Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Chemistry, Physical
Materials Science, Multidisciplinary
Materials Science
MD Multidisciplinary
Chemical Physics
Publication Status: Published
Online Publication Date: 2018-11-14
Appears in Collections:Chemistry
Faculty of Natural Sciences

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