Multifunctional layer-by-layer carbon nanotube–polyelectrolyte thin films for strain and corrosion sensing

Abstract

Since the discovery of carbon nanotubes, researchers have been fascinated by their mechanical and electrical properties, as well as their versatility for a wide array of applications. In this study, a carbon nanotube-polyelectrolyte composite multilayer thin film fabricated by a layer-by-layer (LbL) method is proposed to develop a multifunctional material for measuring strain and corrosion processes. LbL fabrication of carbon nanotube composites yields mechanically strong thin films in which multiple sensing transduction mechanisms can be encoded. For example, judicious selection of carbon nanotube concentrations and polyelectrolyte matrices can yield thin films that exhibit changes in their electrical properties to strain and pH. In this study, experimental results suggest a consistent trend between carbon nanotube concentrations and strain sensor sensitivity. Furthermore, by simply altering the type of polyelectrolyte used, pH sensors of high sensitivity can be developed to potentially monitor environmental factors suggesting corrosion of metallic structural materials (e.g. steel, aluminum).

In situ strain monitoring of fiber-reinforced polymers using embedded piezoresistive nanocomposites

“…The LbL process continues by immersing the substrate (and the initial monolayer) in a negatively charged 1.0 mg mL -1 MWNT (Cheap Tubes, less than 8 nm outer diameter) dispersed in 1.0 wt% poly(sodium 4-styrene sulfonate) (PSS, M w & 1 M, Sigma-Aldrich) solution. Similar to previous studies by Loh et al [33,34], MWNTs are dispersed via steric stabilization by subjecting the MWNT-PSS solutions to 180 min of bath sonication (135 W, 42 kHz) followed by 30 min of high-energy tip sonication (3.178 mm tip, 150 W, 20 kHz). It should be noted that MWNTs are used due to their intrinsic metallic nature and high electronic conductivities, whereas SWNTs can possess metallic or semi-conducting properties.…”

“…Previous studies conducted by Loh et al [33,34] have shown that homogeneous carbon nanotube-PE thin films with no phase segregation can be fabricated by depositing nanometer-thick monolayers of alternating charged PE and nanomaterials (Fig. 1).…”

“…The direct assembly of MWNT-PE thin films onto prepared glass fiber substrates is achieved via a LbL selfassembly process [31][32][33][34]. Previous studies conducted by Loh et al [33,34] have shown that homogeneous carbon nanotube-PE thin films with no phase segregation can be fabricated by depositing nanometer-thick monolayers of alternating charged PE and nanomaterials (Fig.…”

Influence of charge on encapsulation and release behavior of small molecules in self-assembled layer-by-layer microcapsules

“…Polyanions and polycations have been used to prepare self-assembled nano-and microstructures for various applications (Kotz et al, 2001;Ariga et al, 2008). Self-assembly controlled through layer-by-layer (LbL) strategy has shown potential in preparation of delivery systems to smart sensors (Loh et al, 2007;Johnston et al, 2006;Yang et al, 2006;Hammond, 2011). Since the initial reports from Decher and colleagues, there has been a tremendous increase in the number of publications reporting varied applications of self-assembly through LbL strategy (Decher et al, 1992;Decher, 1997).…”

Modification of single-walled carbon nanotube electrodes by layer-by-layer assembly for electrochromic devices

“…Several different groups have deposited modified carbon nanotubes on various substrates for different applications by the ionic LbL approach. [11][12][13][14] In the present work, we have used LbL assembly on separately deposited conducting, transparent SWCNT electrodes rather than incorporate SWCNTs into LbL films. Carrillo et al 15 have used the LbL technique to coat the SWCNT surface with gold nanoparticles and polyelectrolytes, but their approach is more tedious and requires several steps of cross-linking.…”