Surface functionalization of carbon nanotubes with surfactant polymer for enhanced dispersion in nanocomposites

Primary Faculty Mentor’s Name

Mujibur Khan

Proposal Track

Student

Session Format

Poster

Abstract

We report that polyvinylpyrrolidone (PVP) has successfully coated the surface of single walled carbon nanotubes (SWCNTs) using ultrasonic dispersion methods. SWCNTs are single sheets of carbon atoms rolled into a cylindrical shape with exceptional mechanical and electrical properties. CNTs can be used as fillers in composites and have shown to significantly increase the strength and modulus of the material. Producing such high strength polymer nanocomposites require a uniform dispersion of carbon nanotubes within the base polymer matrix. Achieving a stable dispersion of pristine CNTs during processing is challenging and form large clusters due to strong van der Waal forces [1]. To prevent this from occurring, one approach is to modify theCNTsurface with molecules that can eliminate the attractive forces.

In this process, ultrasonic treatment is used to separate the individual tubes and wet the surface of CNTs with PVP. The coating is formed through helical or coil-like wrapping of PVP molecular chains around the circumferential surface of individual nanotubes or nanotube bundles [2]. Morphological characterization of the PVP-wrapped nanotubes was performed using electron microscopy (SEM). The PVP-coated CNTs showed an increase in average diameter, as compared to the average diameter of as-received nanotubes (~5 nm). The significant increase in diameter suggests the formation of a coating layer of PVP on the nanotube surface. TheSEMimages of coated nanotubes also suggest increased debundling of individual nanotubes due to steric hindrance effects induced by the non-covalent PVP wrapping [3]. The results of these effects are evident in the dispersion of the functionalized CNTs in both aqueous (deionized water) and non-aqueous (Xylene+DMAc) suspensions. Compared to pristine CNTs, the treated CNTs displayed significantly stable dispersions in deionized water for 8 weeks. Similar stable suspensions were also achieved in xylene/DMAc for 12 weeks.

The preliminary results suggest that the observed properties of functionalized CNTs can provide a viable route toward effective dispersion in polymer nanocomposites through their enhanced interfacial wettability with the polymer matrix. Further characterization such as FTIR spectroscopy will be used to study the effect of functionalization on the molecular structure of CNTs, by comparing the shifts in the FTIR spectra. In future work, PVP coated CNTs will be used to fabricate nanocomposite fibers.

[1] Huang, Y., and Terentjev, E., 2012, 'Dispersion of Carbon Nanotubes: Mixing, Sonication, Stabilization, and Composite Properties', Polymers, 4(4), pp. 275-295.

[2] Achaby, M., Essassi, E., and Qaiss, A., 2012, 'Coated multi-walled carbon nanotubes for the preparation of nanocomposite films', Society of plastic engineers (SPE).

[3] Didenko, V., Moore, V., Baskin, D., and Smalley, R., 2005, 'Visualization of Individual Single-Walled Carbon Nanotubes by Fluorescent Polymer Wrapping', Nano Letters, 5(8), pp. 1563-1567.

Keywords

carbon nanotubes, nanocomposites, polymers, functionalization

Location

Concourse and Atrium

Presentation Year

2015

Start Date

11-7-2015 2:10 PM

End Date

11-7-2015 3:20 PM

Publication Type and Release Option

Presentation (Open Access)

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Nov 7th, 2:10 PM Nov 7th, 3:20 PM

Surface functionalization of carbon nanotubes with surfactant polymer for enhanced dispersion in nanocomposites

Concourse and Atrium

We report that polyvinylpyrrolidone (PVP) has successfully coated the surface of single walled carbon nanotubes (SWCNTs) using ultrasonic dispersion methods. SWCNTs are single sheets of carbon atoms rolled into a cylindrical shape with exceptional mechanical and electrical properties. CNTs can be used as fillers in composites and have shown to significantly increase the strength and modulus of the material. Producing such high strength polymer nanocomposites require a uniform dispersion of carbon nanotubes within the base polymer matrix. Achieving a stable dispersion of pristine CNTs during processing is challenging and form large clusters due to strong van der Waal forces [1]. To prevent this from occurring, one approach is to modify theCNTsurface with molecules that can eliminate the attractive forces.

In this process, ultrasonic treatment is used to separate the individual tubes and wet the surface of CNTs with PVP. The coating is formed through helical or coil-like wrapping of PVP molecular chains around the circumferential surface of individual nanotubes or nanotube bundles [2]. Morphological characterization of the PVP-wrapped nanotubes was performed using electron microscopy (SEM). The PVP-coated CNTs showed an increase in average diameter, as compared to the average diameter of as-received nanotubes (~5 nm). The significant increase in diameter suggests the formation of a coating layer of PVP on the nanotube surface. TheSEMimages of coated nanotubes also suggest increased debundling of individual nanotubes due to steric hindrance effects induced by the non-covalent PVP wrapping [3]. The results of these effects are evident in the dispersion of the functionalized CNTs in both aqueous (deionized water) and non-aqueous (Xylene+DMAc) suspensions. Compared to pristine CNTs, the treated CNTs displayed significantly stable dispersions in deionized water for 8 weeks. Similar stable suspensions were also achieved in xylene/DMAc for 12 weeks.

The preliminary results suggest that the observed properties of functionalized CNTs can provide a viable route toward effective dispersion in polymer nanocomposites through their enhanced interfacial wettability with the polymer matrix. Further characterization such as FTIR spectroscopy will be used to study the effect of functionalization on the molecular structure of CNTs, by comparing the shifts in the FTIR spectra. In future work, PVP coated CNTs will be used to fabricate nanocomposite fibers.

[1] Huang, Y., and Terentjev, E., 2012, 'Dispersion of Carbon Nanotubes: Mixing, Sonication, Stabilization, and Composite Properties', Polymers, 4(4), pp. 275-295.

[2] Achaby, M., Essassi, E., and Qaiss, A., 2012, 'Coated multi-walled carbon nanotubes for the preparation of nanocomposite films', Society of plastic engineers (SPE).

[3] Didenko, V., Moore, V., Baskin, D., and Smalley, R., 2005, 'Visualization of Individual Single-Walled Carbon Nanotubes by Fluorescent Polymer Wrapping', Nano Letters, 5(8), pp. 1563-1567.