Fabrication and Evaluation of Multiwalled Carbon Nanotube-Containing Bijels and Bijels-Derived Porous Nanocomposites

Abstract

Structures having continuous porous networks are of great interest for applications in areas such as separation, energy storage, and tissue engineering. Bicontinuous interfacially jammed emulsion gels ("bijels") have been actively investigated as templates for fabricating useful structures for such applications. However, the fabrication of bijels-templated porous nanocomposites incorporated with reinforcing or functional nanoparticles (or nanofibers) to provide specific, targeted functions is still a challenge, stemming from the difficulties of fabricating functional nanoparticle-containing bijels. In this study, bijels-derived porous nanocomposites incorporated with multiwalled carbon nanotubes (MWCNTs), which possessed interconnected channels inside the structures, were made via a facile phase inversion technique for bijels fabrication. For the composite manufacture, in the first step of bijels fabrication, MWCNT adsorption into the oil phase of bijels was observed. It was revealed that MWCNTs were physically absorbed into the oil-rich phase without disrupting the bicontinuous structure of bijels. The successful fabrication of non-crosslinked and crosslinked porous structures containing MWCNTs was evidenced through imaging by confocal laser scanning microscopy and scanning electron microscopy, respectively. For potential controlled release applications, an anticancer drug, doxorubicin hydrochloride (DOX), was incorporated into bijels-derived structures and nanocomposites. The in vitro DOX release profiles from drug delivery systems based on bijels-derived MWCNT-containing nanocomposites suggested that the photothermal effect of MWCNTs initiated by near-infrared irradiation could modulate the drug release behavior. Overall, this study has developed a facile approach to fabricate bijels-templated bicontinuous porous structures incorporated with functional nanoparticles (or nanofibers) and opened an avenue for making MWCNT-containing porous nanocomposites for controlled drug release applications.

Bicontinuous Interfacially Jammed Emulsion Gels (Bijels): Preparation, Control Strategies, and Derived Porous Materials

“…Determining how to design and prepare multistage porous materials with a rich structure, excellent performance, and wide applications is still a key point in this field [9,10,33]. As a new method for preparing porous materials, the Bijel templates show obvious advantages [34][35][36]: (1) the preparation process does not need to introduce surfactants; (2) the interfacial layer composed of colloidal particles is more stable and rigid; (3) the microstructure of porous materials can be regulated by changing the wettability, concentration, and charge property of the colloidal particles; and (4) the porous materials prepared using the method have uniform pore channels, narrow pore size distribution, and large pore size (nanometer to micrometer). The simultaneous presence of interconnected polar and nonpolar domains makes these porous materials suitable for various applications in the fields of molecular encapsulation [25,37], tissue engineering [38], drug delivery [39], and electrochemistry [40].…”

Roll‐to‐Roll Fabrication of Bijels via Solvent Transfer Induced Phase Separation (R2R‐STrIPS)

“…[14,15,19,20] Additionally, potentially scalable batch fabrication methods have been employed to generate bijels via other methods than STrIPS. [18,[21][22][23][24] As opposed to bijel production, the mass production of flat-sheet NIPS membranes can be readily accomplished via doctor blade-, roll-, and slot die-coating. [25] Flat-sheet NIPS membrane production via these methods is straightforward due to the high viscosity (≈0.4-10 Pa s) of the NIPS precursor solution.…”

Polymerizable bijels prepared by a direct-mixing method

“…22 It was known that bijels constructed via arrested spinodal decomposition can yield structures with approximately zero mean curvature, being ascribed to the fact that the particles at the interface can be equally wetted by both liquids, and thus do not impose any curvature upon the system. 3 In this work, the shear force was applied to trigger the bicontinuous structures, accompanying the appearance of droplets in the early stage of bijel formation. 13 As shown in Fig.…”

“…Bijels are used as templates for manufacturing bicontinuous structures by polymerizing one of the liquid phases and are desirable for applications in catalysts, fuel cells, electrodes, micro-reactors, tissue engineering and separation processors. [3][4][5][6][7] The original bijels were fabricated via spinodal decomposition, which uses phase separation of partially miscible liquids during quenching to create a bicontinuous arrangement of fluid domains, and then employs colloidal particles adsorbing at the interface as stabilizers. [8][9][10] This method requires precise control of the quenching rate, which has strict criteria for the melting and boiling points and the relative densities of liquid pairs.…”