posted on 2022-02-01, 23:14authored byGang Ye, Wytse Talsma, Karolina Tran, Yuru Liu, Sietske Dijkstra, Jiamin Cao, Jianhua Chen, Junle Qu, Jun Song, Maria Antonietta Loi, Ryan C. Chiechi
This paper describes
the effectiveness of donor–acceptor
(D-A) conjugated polymers to disperse and select for semiconducting
single-walled carbon nanotubes (s-SWCNTs) when enhanced by the inclusion
of polar oligoethylene glycol-based side chains, without altering
the D–A backbone. We designed and synthesized two sets of naphthalenediimide(NDI)-alt-bithiophene(T2)-based conjugated polymers with one of
two alkyl side chains (decyl and dodecyl chains) of different lengths
and with or without polar triethylene glycol side chains. The resulting
low-band-gap copolymers all effectively disperse and select for s-SWCNT,
but the inclusion of polar side chains enhances the interactions between
the polymer backbone and the walls of the s-SWCNTs relative to the
polymers with only alkyl side chains. As a result, the wrapping and
selection efficiency of the polymer-SWCNT systems with polar side
chains are both significantly enhanced. We further optimized the binding
energy and surface coverage by combining glycol ether and dodecyl
side chains to maximize wrapping efficiency, leading to a field-effect
mobility of 2.82 cm2 V–1 s–1 and on/off current ratios of ∼2 × 107 in
polymer-wrapped SWCNTs. Our results provide insight into the role
of the side-chain interactions in the polymer wrapping and dispersion
technique, and, because we focus on manipulating side chains, they
can be generalized for other conjugated polymer backbones.