Functionalization of MWCNT

Figure 5.5. Mechanical properties of PE and MWCNT-PE nanocomposites as a function of MWCNT loading, McNally et al. (53).

In addition, Song et al. (76) used a one-step condensation synthesis method to prepare the PLA-MWCNTnanocomposites. For detailed experimental conditions, refer to Song et al. (76). The nanocomposites were prepared using pure and carboxylic-acid-functionalized MWCNTs. As with the other studies, the carboxylic-acid-functionalized MWCNTs dispersed better in PLA compared with non-functionalized MWCNTs. Overall, it can be inferred from the studies described in this section that the functionalization of MWCNTs is a very important step in the process of making a nanocomposite, as it will help to disperse the nanotubes uniformly, which will eventually create the superior properties of the resulting nanocomposite. In addition, among the currently available methods for functionalization, carboxylic-functionalization is the best for uniform dispersion. 

A sequential chemical processing of acidification-acylation-esterification was adopted by Liu et al. [60] to perform the functionalization of MWCNTs with... 

Recently, Gao and co-workers " developed a facile approach to the functionalization of MWCNTs and SWCNTs via nitrene chemistry, and functional groups such as hydroxyl, carboxyl and amino could be immobilized... 

Scheme 5.3 Functionalization of MWCNTs with poly(GMA-OH) by ATRP, conversion of the hydroxyl groups of poly(GMA-OH) into carboxylic groups, and metal sequestration/reduction by the grafted polyacid chains. ...

Functionalization of MWCNTs by the layer-by-layer click chemistry (LbL-CC) approach and further modification of the functionalized MWCNTs with fluorescent dye and polystyrene by click chemistry. Reprinted with permission from Zhang et al... 

Scheme 5.16 Functionalization of MWCNTs with HPG by anionic ROP and conjugation of rhodamine 6B with hydroxyl groups by N,N"-dicyclohexylcarbodiimide (DCC) coupling chemistry. Reprinted with permission from Zhou et al ...

Scheme 5.3 Functionalization of MWCNTs with poly(GMA-OH) by ATRP...

Figure 9.23 Frequency dependence of losses due to reflection (SEj ) and absorption (SE ) for MWCNT-loaded PANl nanocomposites having different loadings of MWCNT relative to aniline monomer viz. PCNTO (0.0 wt.%), PCNT5 (5.0 wt.%), PCNTIO (10 wt.%), PCNT20 (20 wt.%), and PCNT25 (25 wt.%). Loss tangent (tan 6) of in-situ synthesized PANl-MWCNT nanocomposites as a function of MWCNT loading. Reprinted from Ref [4] with permission from Elsevier.

Figure 4.11 Two-point electrical conductivity measurements of MWCNT/ PS electrospun fibrous films as a function of MWCNT concentration. Reprinted from Ref. 14S with permission from SPIE.

After the discovery of carbon nanotube (CNT) by Ijima (1991), extensive works have been devoted in extracting the optimum properties of the CNTs. Wu (2009) studied PTT/MWCNT composites. The hydroxyl functionalized (MW-CNT-OH) behaves as anchoring sites for the PTT grafted with acrylic acid (PTT-g-AA) (compare to Scheme 1). The functionalization of MWCNT improves the compatibility and dispersibility of the MWCNT in the matrix of PTT. The thermal and mechanical properties (compare to Tables 14 and 15) show a dramatic increase leading to the conclusion that functionalized MWCNT can be used for preparing high performance PTT nanocomposites. 

Scheme 7.1 Functionalization of MWCNTs with PU chains. Reproduced from Ref. [14] with permission.

Figure 7.16 Thermal conductivity of MWCNT/polyether-based WPU nanocomposites as a function of MWCNT content. Reproduced from Ref [8] with permission.

Lemes et al. (2008) verified that the functionalization of MWCNT with carboxylic groups (MWCNT-COOH) affected the dispersion of CNT in the matrix in PHBV nanocomposites, even in extremely low MWCNT-COOH concentration (0.06 %). SEM micrographs of fractured surface of PHBV/MWCNT and PHBV/ MWCNT-COOH showed that the diameter of regions of CNT agglomerates were larger in PHBV/MWCNT than in the PHBV/MWCNT-COOH nanocomposites. Changes in the thermal behavior of PHBV matrix and a nucleating effect promoted by CNT were observed in both nanocomposites. 

Figure 5.3 Conductivity (four-point measurements) as a function of MWCNT concentration for MWCNT/iPP-g-MA and MWCNT/PS nanocomposites.

Figure 7.3 Four-point conductivity ofMWCNT/PS composite as a function of MWCNT content VGCNT2s fo) IPCNTs ( ]. Each point of the curve is the average of several measurements performed several times on several locations on both sides of the nanocomposite films.

Figure 5.25 Nucleation efficiency (calculated with Eq. 5.6) as a function of MWCNT content for PCL/MWCNT nanocomposites. Adapted from Trujillo et al. [241]. Reproduced with permission of Elsevier.

Du B, Handge U, Wambach M, Abetz C, Rangou S, Abetz V. Functionalization of MWCNT with P(MMA-co-S) copolymers via ATRP influence on localization of MWCNT in SAN/PPE 40/60 blends and on rheological and dielectric properties of the composites. Polymer 2013 54 6165-76. 

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