Bimodal Latex Effect on Spin-Coated Thin Conductive Polymer-Single-Walled Carbon Nanotube Layers.
We synthesize two differently sized poly(methyl methacrylate-co-tert-butyl acrylate) latexes by emulsion polymerization and mix these with a sonicated single-walled carbon nanotube (SWCNT) dispersion, in order to prepare 3% SWCNT composite mixtures. We spin-coat these mixtures at various spin-speed rates and spin times over a glass substrate, producing a thin, transparent, solid, conductive layer. Keeping the amount of SWCNTs constant, we vary the weight fraction of our smaller 30-nm latex particles relative to the larger 70-nm-sized ones. We find a maximum in the electrical conductivity up to 370 S/m as a function of the weight fraction of smaller particles, depending on the overall solid content, the spin speed, and the spin time. This maximum occurs at 3-5% of the smaller latex particles. We also find a more than 2-fold increase in conductivity parallel to the radius of spin-coating than perpendicular to it. Atomic force microscopy points at the existence of lanes of latex particles in the spin-coated thin layer, while large-area transmission electron microscopy demonstrates that the SWCNTs are aligned over a grid fixed on the glass substrate during the spin-coating process. We extract the conductivity distribution on the surface of the thin film and translate this into the direction of the SWCNTs in it.
Mohammad-Amin
MA
Moradi
Katalin
K
Larrakoetxea Angoitia
Polymer Technology Group Eindhoven B.V. (PTG/e), P.O. Box 6284, 5600 HG, Eindhoven, The Netherlands.
Stefan
S
van Berkel
Karthikeyan
K
Gnanasekaran
Heiner
H
Friedrich
Johan P A
JP
Heuts
Institute for Theoretical Physics, Utrecht University , Leuvenlaan 4, 3584 CE Utrecht, The Netherlands.
Paul
P
van der Schoot
Institute of Chemical and Engineering Sciences , 1 Pesek Road, Jurong Island 627833, Singapore.
Alex M
AM
van Herk