Dual electro- and magneto-induced bending actuators of magnetite-loaded agarose ionogels.

Magnetic ionogels are a new kind of gel composites which combine the elastic properties from the swollen gel matrix and the magnetic properties from a magnetic filler. The dual electro-magneto-responsive agarose ionogels (AG IGels) were fabricated by a solution casting method using 1-butyl-3-methylimidazolium chloride [Bmim][Cl] as the ionic liquid solvent, and embedded with magnetite nanoparticles (Fe3O4 NPs). The addition of Fe3O4 NPs induced the high bending responses under applied electric and magnetic fields via the electronic polarization and magnetic interaction. The 3.0 wt.% Fe3O4/AG MagIGel showed the largest deflection distances relative to other magnetic gel composites; 14.92, 8.96, and 21.63 mm under the applied electric fields of 600 V/mm in silicone oil, 60 V/mm in air, and under the applied magnetic field of 600 G in air, respectively. The bending distances were of comparable in magnitudes to other electro-magneto-responsive materials. Thus, the fabricated Fe3O4/AG MagIGels are demonstrated here as potential for soft electric-magnetic actuator applications.

Metformin delivery via iontophoresis based on κ-carrageenan cryogels.

Transdermal drug delivery system (TDDS) is the system for transmitting a drug through the skin into the blood circulation. In this work, κ-Carrageenan (κC) was used as the drug matrix material. The porous κC matrices were fabricated by dissolving the κC in deionized water to obtain hydrogels and then using the freeze-dryer to obtain cryogels. The porous (κC) matrices showed interconnected pore sizes varying between 6.05 to 25.8 nm. In the drug release experiments, the drug diffusion coefficient increased and the drug release duration was reduced with decreasing κC concentration due to the larger κC pore sizes. The diffusion coefficient increased with a shorter release time under the applied electric strength of +1.0 V due to the electro-repulsive force between the Metformin and the anode. For the drug release-permeation of the κC 0.8 % v/v cryogel through the pig skin under applied positive electrical potentials, the amounts of drug release-permeation and diffusion coefficients were enhanced with shorter durations relative to without electrical potential. The κC 0.8 % v/v matrix at the applied electric strength of +6.0 V has been shown here to be potential to be used as the Metformin transdermal controlled delivery patch for abdominal obesity and diabetes.

Synthesis of Highly Conductive Poly(3-hexylthiophene) by Chemical Oxidative Polymerization Using Surfactant Templates.

Poly(3-hexylthiophene) (P3HT) was systematically synthesized by chemical oxidative polymerization in chloroform with ferric chloride (FeCl3) as the oxidizing agent and various surfactants of the shape templates. The effects of 3HT: FeCl3 mole ratios, polymerization times, and surfactant types and concentrations on the electrical conductivity, particle shape and size were systematically investigated. Furthermore, dodecylbenzenesulfonic acid (DBSA), p-toluenesulfonic acid (PTSA), sodium dodecyl sulfate (SDS), and sodium dioctyl sulfosuccinate (AOT) were utilized as the surfactant templates. The P3HT synthesized with DBSA at 6 CMC, where CMC stands for the Critical Micelle Concentration of surfactant, provided a higher electrical conductivity than those with PTSA, SDS and AOT. The highest electrical conductivity of P3HT using DBSA was 16.21 ± 1.55 S cm-1 in which the P3HT particle shape was spherical with an average size of 1530 ± 227 nm. The thermal analysis indicated that the P3HT synthesized with the surfactants yielded higher stability and char yields than that of P3HT without. The P3HT_DBSA electrical conductivity was further enhanced by de-doping and doping with HClO4. At the 10:1 doping mole ratio, the electrical conductivity of dP3HT_DBSA increased by one order of magnitude relative to P3HT_DBSA prior to the de-doping. The highest electrical conductivity of dP3HT_DBSA obtained was 172 ± 5.21 S cm-1 which is the highest value relative to previously reported.

Synthesis and characterization of CoxFe1-xFe2O4 nanoparticles by anionic, cationic, and non-ionic surfactant templates via co-precipitation.

The cobalt ferrite nanoparticles (CoxFe1-xFe2O4) were synthesized by the surfactant templated co-precipitation method using various surfactants namely sodium dodecyl sulfate (SDS), hexadecyltrimethylammonium bromide (CTAB), and Tween20. Under the substitution, the CoxFe1-xFe2O4 particles were synthesized at various Co2+ and Fe2+ mole ratios (x = 1, 0.6, 0.2, and 0) with the SDS. The cobalt ferrite nanoparticles were characterized for their morphology, structure, magnetic, and electrical properties. All CoxFe1-xFe2O4 nanoparticles showed the nanoparticle sizes varying from 16 to 43 nm. In the synthesis of CoFe2O4, the SDS template provided the smallest particle size, whereas the saturated magnetization (Ms) of CoFe2O4 was reduced by using CTAB, SDS, and Tween20. For the CoxFe1-xFe2O4 as synthesized by the SDS template at 1.2 CMC, the Ms increased with increasing Fe2+ mole ratio. The highest Ms of 100.4 emu/g was obtained from the Fe3O4 using the SDS template. The Fe3O4 nanoparticle is potential to be used in various actuator and biomedical devices.

Synthesis and Characterization of Fe0.8Mn0.2Fe2O4 Ferrite Nanoparticle with High Saturation Magnetization via the Surfactant Assisted Co-Precipitation.

Manganese ferrite nanoparticles (MnFe2O4) were synthesized via surfactant-assisted co-precipitation, where sodium dodecyl sulfate (SDS) was used as the template to control particle size at various SDS concentrations. The substitutions of iron (II) (Fe2+) into the MnFe2O4 ferrite nanoparticles were carried out to obtain Fe(1-x)MnxFe2O4, with various Mn2+: Fe2+ molar ratios. The synthesized ferrite nanoparticles were characterized by the Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analyzer (TGA), X-ray diffractometer (XRD), energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), two-point probe, and vibrating sample magnetometer (VSM) techniques. The experimental Mn:Fe mole ratios of the Fe(1-x)MnxFe2O4 ferrite nanoparticles were verified to be in agreement with the theoretical values. The synthesized MnFe2O4 and Fe(1-x)MnxFe2O4 ferrite nanoparticles were of mixed spinel structures, with average spherical particle sizes between 17-22 nm, whereas the magnetite ferrite nanoparticles (Fe3O4) were of the inverse spinel structure. They showed soft ferromagnetic behavior. The synthesized Fe0.8Mn0.2Fe2O4 ferrite nanoparticle possessed the highest saturation magnetization of 88 emu/g relative to previously reported work to date.

Facile formation of agarose hydrogel and electromechanical responses as electro-responsive hydrogel materials in actuator applications.

The agarose hydrogels (AG HyGels) were fabricated by a solvent casting method at various agarose concentrations, resulting in the 3D hydrogel networks via the physical crosslinking from the hydrogen bonding. The actuator performances were investigated at various agarose contents and electric field strengths. For the electromechanical properties, the AG HyGel_12.0 %v/v possessed the highest storage modulus (G') and storage modulus relative response (ΔG'/G'0) of 4.48 × 106 Pa and 1.07, respectively under applied electric field strength of 800 V/mm due to the electrostriction effect. In the electro-induced bending measurement, the highest deflection distance was obtained from the AG HyGel_2.0 %v/v due to its initial lower rigidity. Relative to other bio-based hydrogels, the present AG HyGels are first demonstrated here as electroactive materials showing comparable magnitudes in the electroactive responses, but with the simple fabrication method without toxic ingredients required. Thus, the present AG HyGels are potential material candidates for soft actuator applications.