P3HT Nanowire formation in solution

Epitaxial Growth of Poly(3-hexylthiophene) on Carbon NanotubesJianhua Liu, Jianhua Zou and Lei Zhai*

NanoScience Technology Center, Department of Chemistry, University of Central Florida, 12424 Research Parkway Suite 400, Orlando, FL 32826

Orange Purple

Nanofibrils

dispersion @ RT

P3HT

hot solution

Cooling to RT

in marginal solvents

500 nm 50 nm

Marginal solvents: anisole, cyclopentanone, etc.

Width=12-15 nm; Length=1-10 μm; Height=3-7 nm

Length

Heig

ht

P3HT

Thermochromism

Figure 1. TEM images of P3HT nanowires obtained

via a solution method.

Pristine Carbon nanotubes (CNTs) dispersed by P3HT

Figure 2. TEM images of SWCNTs (A) and MWCNTs (B)

dispersed by P3HT in chloroform. (Scale bar: 200 nm )

P3HT nanowire formation induced by CNTs (epitaxial growth)

Figure 4. TEM images of P3HT supramolecular structures

on MWCNTs (A and C) and SWCNTs (B and D).

(Scale bar: A, B = 1μm, C, D = 100 nm)

Width: 12~15 nm.

Length: from tens to hundreds nm.

Height: 3-5 nm

Figure 5. Tapping-mode AFM height images (top)

and cross sections of the line trace (bottom) of P3HT

supramolecular structures on MWCNTs (A) and

SWCNTs (B)

Length control of P3HT nanowires on CNTs

Hierarchal P3HT/CNT supramolecular structures were

fabricated through a CNT induced P3HT crystallization

strategy.

The length of P3HT nanowires on CNTs can be controlled

by tuning the P3HT/CNT mass ratio.

The quasi-isothermal crystallization process monitored by

in-situ UV-Vis spectroscopy indicates the CNT nucleation

effect and the first-order kinetics of P3HT nanowire growth.

This bottom-up strategy provides a general approach to

build functional conductive supramolecular structures on

CNTs

300 400 500 600 700 8000.0

0.4

0.8

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Absorb

ance

Wavelength nm

SWCNTs

MWCNTs

Kinetics Study by UV-Vis (Quasi-isothermal process )

Acknowledgments: NSF CAREER award DMR 0746499

Figure 7. In situ UV-Vis monitored isothermal P3HT nanowire formation at room temperature ([P3HT] = 0.05 mg/mL,

P3HT/CNT=7; A: without CNTs; B: with MWCNTs; C: with SWCNTs), and UV-Vis absorbance change at 600 nm of

the P3HT suspension during the monitored process (D; Solid lines are the fitted first-order kinetics curves).

Figure 6. TEM images of P3HT nanowires formed on SWCNTs at different P3HT/ SWCNT mass ratio of 40

(A); 22 (B); 10 (C); 5 (D). (Scale bar: 200 nm)

Conclusions

References

P3HT: Mn=14800, PDI=1.2; Regioregularity = 96%

Figure 3. UV-Vis absorption spectra of MWCNTs and

SWCNTs dispersion.

[SWCNT] = 0.008 mg/mL

[MWCNT] = 0.008 mg/mL

Dispersed CNTs were added into P3HT anisole solutions as nucleation seeds to grow P3HT nanowires.

A B

A B

DC

Centipede-like morphology

A B

A B

P3HT nanowires on MWCNTs are affected by the nanotube diameter and surface curvature. MWCNTs with large

diameter and less surface curvature have a higher density of nanowires.

P3HT nanowires on SWCNTs are more uniform because SWCNTs are straight with similar diameters.

MWCNTs Vs SWCNTs

Length of P3HT nanowires can be controlled by tuning the P3HT/CNT mass ratio.

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1. Liu, J.; Zou, J.; Zhai, L. Macromol. Rapid. Commun. 2009, 30, 1387-1391.

2. Zou, J.; Liu, L.; Chen, H.; Khondaker, S. I.; McCullough, R. D.; Huo, Q.; Zhai, L. Adv. Mater. 2008, 20, 2055-2060.

3. Ihn, K. J.; Moulton, J.; Smith, P. J. Poly. Sci. B: Poly. Phys. 1993, 31, 735-742.

4. Li, L.; Li, C. Y.; Ni, C. J. Am. Chem. Soc. 2006, 128, 1692-1699.

Figure 8. Schematic illustration of hierarchal 2D P3HT/CNT

supramolecular structures

455 nm: π-π* electronic transition of isolated P3HT chain in solution

510, 550 and 600 nm: π-π* electronic transition and a strong lattice vibration of P3HT in solid state

Pronounced nucleation effect of CNTs and first order kinetics of P3HT nanowire growth