A controllable way to measure the interfacial strength between carbon nanotube and polymer using a nanobridge structure

Abstract

The interfacial strength between an embedded carbon nanotube (CNT) and a polymer matrix is a direct indicator of the interfacial load transfer which significantly impacts the effective mechanical properties of CNT/polymer nanocomposites. However, unavoidable kinks or entanglement of the CNTs in the polymer may complicate the characterization of the interface as measured through nanopullout experiments. In the current work a CNT/polymer nanobridge structure in a suspended polymer film is developed to allow the observation of the embedded portion of the CNT after the pullout process. The nanobridge structure was created on the basis of phase separation of a polymer blend, self-assembly of the CNTs in liquid flow, and ductile fracture of the polymer under thermal and solvent treatment. This structure accommodates a nanomechanical interfacial characterization method where a transverse force applied on the suspended CNT using an atomic force microscope results in an axial pullout force, which is

Recent Advances in Characterization Techniques for the Interface in Carbon Nanotube-Reinforced Polymer Nanocomposites

“…Atomic force microscopy may be the preferred technique for characterization of the interface due to its advantages for high-precision and highsensitivity measurements [99,100]. is microscope technique can also serve as a means to elucidate the properties of the interface in polymer nanocomposites [101,102]. Two particularly powerful approaches to characterize the properties of the interface are the pull-out method [103] and the peeling method [104].…”

“…Finally, the embedment depth of an individual carbon nanotube cannot be controlled and measured easily using this nano-pull-out test technology. To observe the embedded portion of such a carbon nanotube after the process of a nano-pull-out test, Nie et al [101] developed a carbon nanotube-polymer nanobridge structure in a polymer lm, as described below.…”

“…To address this issue, Nie et al [101] developed a controllable method to measure the strength of the interface with the help of an individual nanobridge in a suspended polymer lm and proposed an e ective way to evaluate the e ciency of interfacial load transfer, as illustrated in Figure 4. Such a microscopic structure is constructed on the basis of the self-assembly of multiwalled carbon nanotubes in liquid ow and the phase separation of polymer blends and the ductile fracture of such blends after thermal and chemical treatment, as shown in Figure 5(a).…”

“…e average strength of the interface formed by an individual multiwalled carbon nanotube and a poly(methyl methacrylate) matrix is about 48 MPa, measured by using this method [101]. Such a controllable method can be used to measure the strength of the interface for the nanocomposites due to the ability to form an image of the embedded portion of an individual carbon nanotube and to the high-resolution imaging during the loading process [101]. It is important to note that this technique is only applicable to the polymers with the ability to form a phase separation structure.…”

“…If such a stress is transferred to Figure 4: (a and b) Schematic diagram of the pull-out process applied to an individual carbon nanotube suspended within a free-standing polymer thin film using an atomic force microscope. Schematic diagram of the fabrication process of a suspended holey film as being formed from a polymer blend: (c) a hydrophobic polymer thin film coated on the surface of a hydrophilic glass slide using a dip-coating method, (d) release of such a film from the glass slide by water, (e and f ) transfer of the film to a grid made of copper, and (g) hole-opening using cyclohexane as a solvent and then using a heat treatment method (adapted with permission from reference [101]; copyright 2017, Elsevier Ltd).…”