Microbeads and Hollow Microcapsules Obtained by Self-Assembly of Pickering Magneto-Responsive Cellulose Nanocrystals

Abstract

Cellulose microbeads can be used as immobilization supports. We report on the design and preparation of magneto-responsive cellulose microbeads and microcapsules by self-assembled shells of cellulose nanocrystals (CNC) carrying magnetic CoFe2O4 nanoparticles, that is, a mixture of isotropic and anisotropic nanomaterials. The magnetic CNCs formed a structured layer, a mesh, consisting of CNCs and magnetic particles bound together on the surface of distinct droplets of hexadecane and styrene dispersed in water. Because of the presence of CNCs the highly crystalline mesh was targeted to provide an improved barrier property of the microbead shell compared to neat polymer shells, while the magnetic particles provided the magnetic response. In situ polymerization of the styrene phase led to the formation of solid microbeads (∼8 μm diameter) consisting of polystyrene (PS) cores encapsulated in the magnetic CNC shells (shell-to-core mass ratio of 4:96). The obtained solid microbeads were ferromagnetic (saturation magnetization of ∼60 emu per gram of the magnetic phase). The magnetic functionality enables easy separation of substances immobilized on the beads. Such a functionality was tested in removal of a dye from water. The microbeads were further utilized to synthesize hollow microcapsules by solubilization of the PS core. The CNC-based, magneto-responsive solid microbeads and hollow microcapsules were characterized by electron microscopy (morphology), X-ray diffraction (phase composition), and magnetometry (magnetic properties). Such hybrid systems can be used in the design of materials and devices for application in colloidal stabilization, concentration, separation, and delivery, among others.

Flexible and Tailorable Alkylviologen/Cellulose Nanocrystals Composite Films for Sustainable Applications in Electrochromic Devices

“…CNCs were prepared from cotton pulps by sulfuric acid hydrolysis as common mineral acid mentioned in majority literatures . The pulps were broken into flocculent by grinder machine (JYS−M01) and then immersed into 4 wt% aqueous NaOH solution for 24 h at room temperature.…”

“…CNCs were prepared from cotton pulps by sulfuric acid hydrolysis as common mineral acid mentioned in majority literatures. [47][48][49] The pulps were broken into flocculent by grinder machine (JYSÀM01) and then immersed into 4 wt% aqueous NaOH solution for 24 h at room temperature. The above soaked pulps were sufficiently washed with deionized water until neutral pH and then entirely dried in a vacuum oven.…”

PMMA@SCNC composite microspheres prepared from pickering emulsion template as curcumin delivery carriers

“…In particular, CNCs display many unique properties, such as high surface area, enhanced chemical reactivity, high mechanical durability, good optical properties along with renewability, biocompatibility and biodegradability, which provide considerable applications in drug delivery, food, gas barriers, and purification . Recently, CNCs were also used to stabilized emulsion had been reported by some researchers, for example, Kalashnikova et al . used cellulosic colloidal nanorods of different origins to investigate the effect of various elongated shapes adsorbed at the oil–water interface of Pickering emulsion, and also modulated the amphiphilic properties of the nanocrystals by changing the surface charge density to investigate two sources of cellulose: cotton linters and bacterial cellulose.…”

Fibrillated cellulose in heterophase polymerization of nanoscale poly(methyl methacrylate) spheres

“…Therefore, the oil phase of the emulsions was replaced by styrene, which was subsequently polymerized to polystyrene particles in micrometer range, and thus, the appearance of the emulsions could be visualized by SEM [20]. In this way, different effects on the emulsion appearance and stability, such as the NCC aspect ratio, surface charge or modification, or the ionic strength, were assessed [21][22][23][24][25].…”