Simple co-electrodeposition of functionalized multi-walled carbon nanotubes/chitosan composite coating on mainspring for enhanced modulus of elasticity

Abstract

Co-electrodeposition of functionalized multi-walled carbon nanotubes (f-MWCNTs) with chitosan was performed on pieces of a stainless steel mainspring. Under moderate conditions, composite coatings with controllable thickness from a few hundred nanometers to tens of micrometers can be achieved. After coating an 8 microm composite layer on a piece of mainspring 120 microm thick (i.e. 6.7% increase in thickness), the Young's modulus of the mainspring was found to have increased by more than approximately 25%. Moreover, the coated mainsprings possess much stronger mechanical strength as demonstrated by fatigue tests. The significant enhancement of Young's modulus and intrinsic strength are mostly attributed to the effect exerted by the subtle combination of chitosan and MWCNT. In the current study, the intensive cross-linkages formed between the -COOH groups in f-MWCNTs and the hydroxyl (-OH) and amino (-NH2) groups in chitosan were exploited. The chitosan molecular chains and f-MWCNTs both chemically react and physically knot with each other, leading to a three-dimensional interlaced f-MWCNT/chitosan composite coating. The reported co-electrodeposition provides a simple approach to form a stable, reproducible and rigid f-MWCNTs composite coating, which leads to the realization of a high-performance mainspring with reinforced mechanical strength.

Electrophoretic deposition of carbon nanotubes: recent progress and remaining challenges

“…EPD can even be used to infiltrate porous non-conductive substrates, such as polymeric or ceramic scaffolds [147]. Polymeric substrates in different hierarchical structures have been coated with CNTs for a wide range of applications [52,79,119,133,148]. A typical example (shown in Figure 6) involves infiltration of CNTs into a polyurethane (PUR) foam [119], situated in the middle of the EPD cell between two stainless steel electrodes; the CNTs were driven through the pores under the application of a DC field.…”

“…The introduction of a reversed electric field (post-EPD) effectively detaches the Buckypaper from the metallic substrate without appreciable degradation of surface morphology or mechanical properties [192]. Composite coatings may be formed directly on substrates by either co-deposition or post-EPD infusion of a variety of matrices (Deposition of preassembled composite particles); the presence of CNTs is reported to significantly increase the modulus and hardness of polymer matrix composites [52,177], increase the hardness of metal matrices, as well as to inhibit cracking of ceramic coatings. Masked co-deposition of CNTs and boehmite nanoparticles was used to produce composite microgears [168].…”

Electrophoretic deposition of biomaterials

“…Many investigations have focused on the fabrication of CHIT -CNT and CHIT -CNT -HA composites, containing pristine CNT (Grandfield et al 2009), as well as CNT containing cationic and anionic functional groups (Casagrande et al 2008). In all cases, composite materials containing CNT showed improved mechanical properties (Jia et al 2009). In related research, composite CHIT -CNT films were developed for the fabrication of efficient impedance cell sensors (Hao et al 2007).…”

Mulberry leaf extract mediated synthesis of gold nanoparticles and its anti-bacterial activity against human pathogens

“…Nanoparticles of noble metals belong to the most extensively studied colloidal systems in the field of nanoscience and nanotechnology. Noble metals such as Au, Ag, Pd, Pt and Cu have been widely used for the synthesis of stable colloids which are useful in the areas of optoelectronics [1], catalysis [2], photothermal therapy [3], surface enhanced Raman scattering (SERS) detection [4] and biological labelling [5]. Among several metal nanoparticles, gold nanoparticles (Au-NPs) have been considered an important area of research due to their unique and intense plasmon resonance in the visible range and their applications in biomedical field.…”