Polymer Phase Research Articles

An electrochemically active textile current collector with a high areal capacity and a strong energy recovery effect using an interfacial interaction assembly

Conventional current collectors in lithium-ion batteries (LIBs) are generally nonactive components. However, enhancing their electroactive properties and increasing the electroactive surface area can significantly improve the areal energy performance of next-generation battery electrodes. Herein, we introduce an electrochemically active textile current collector that delivers high energy storage performance, achieved through interfacial interaction assembly-induced electroplating. We first prepared metal nanoparticle/multiwalled carbon nanotube multilayer-incorporated cotton textiles using complementary interaction-mediated layer-by-layer assembly, and subsequently electroplated them with Cu. The resulting textile exhibited a high areal capacity of ∼3.27 mA h cm−2 at 0.875 mA cm−2, excellent cycling stability, and a strong energy recovery effect, thanks to the synergistic contributions of the large active surface area of the fibril structure, the robust interfacial assembly, and the formation of a metal oxide NP/pseudocapacitive polymeric gel-like phase at the electrode/electrolyte interface. Moreover, when incorporating Li4Ti5O12 with a theoretical capacity of 175 mA h g − 1 into our textile current collector, the specific capacity and areal capacity of the LIB anode can be increased up to ∼573 mA h g − 1 and 8.60 mA h cm−2 (at 15 mg cm−2 LTO), respectively, outperforming those of previously reported LTO-based anodes.

Synthesis of patterned polyHIPE-hydrogel composite materials using thiol-ene chemistry

Elastomeric materials combining multiple properties within a single composite are highly desired in applications including biomaterials interfaces, actuators, and soft robotics. High spatial resolution is required to impart different properties across the composite for the intended application, but many techniques used to prepare these composites rely on multistep and complex methods. There is a need for the development of simple and efficient platforms to design layered composite materials. Here, we report the synthesis of horizontally- and vertically-patterned composites consisting of PDMS-based polymerized high internal phase emulsion (polyHIPE) porous elastomers and PDMS/PEG hydrogels. Composites with defined interfaces that were mechanically robust were prepared, and rheological analysis of the polyHIPE and hydrogel layers showed storage moduli values of ∼ 35 kPa and 45 kPa respectively. The compressive Young’s Modulus and maximum strain of the polyHIPEs were dependent on the thiol to ene ratio in the formulation and obtained values ranging from 6 to 25 kPa and 50–65% respectively. The mechanical properties, total porosity of the polyHIPE, and swelling ratio of the hydrogel were unaffected by the patterning technique compared to non-patterned controls. PolyHIPE-hydrogel composite materials having up to 7-different horizontally pattered layers could be prepared that could expand and contract up hydration and drying.

Reprocessable, Photothermal Phase Change Material-Based Hybrid Polymeric Networks for Solar-to-Thermal Energy Storage

Polymeric photothermal phase change material composite (PPCMC) networks with excellent reprocessability, high latent heat, and intrinsic network stability have the great advantages of solar energy storage and conservation and environmental protection resulting from the covalent crosslinking network structure and long-life inorganic photothermal agents. Herein, the reprocessable PPCMCs were successfully prepared by introducing the reactive diisocyanate-terminated poly(ethylene glycol) (PEG) and multiple amino-functionalized carbon black (CB)that serve as the phase change component and the photothermal curing agent, respectively. The phase change properties, mechanical strength, and photothermal efficiency of PPCMCs can be tuned by the chain length of PEG and the loading content of CB and the catalyst. PPCMCs possess the largest latent heat of 126.7 J/g, the highest photothermal conversion efficiency of 89.0%, superior shape stability even at 140 °C, high thermal stability beyond 300 °C, and reprocessing ability by introducing the catalyst of the transcarbamoylation reaction. Also, the PPCMCs exhibit high thermal reliability after accelerated thermal cycling and reprocessing, featuring nearly consistent chemical and crystalline structures, latent heat, phase change temperature, and photothermal properties. This synthetic strategy provides an alternative to obtain multi-functional PPCMCs due to the enhanced interfacial interaction between inorganic particles and the polymer matrix via covalent linkages.

Hochdielektrischer Poly(vinylidenfluorid)‐basierter Ionogel‐Feststoffelektrolyt für den gleichmäßigen Lithium‐Ionen‐Transport

AbstractIonische Flüssigkeiten (ionic liquids, ILs) eingebettet in feste Polymer‐Elektrolyte (iono‐SPEs) weisen eine hohe ionische Leitfähigkeit auf, zeigen jedoch einen nicht‐uniformen Li+‐Transport in den verschiedenen Phasen. In dieser Arbeit wird gezeigt wie der Li+‐Transport in Polymerphasen erheblich durch ein Poly(vinylidenfluorid‐trifluorethylen‐chlorotrifluorethylen)‐Netzwerk [P(VDF‐TrFE‐CTFE), PTC] ILs zur Herstellung von iono‐SPEs verbessert werden kann. Im Gegensatz zu PVDF zeigt PTC mit geeigneter Polarität eine schwächere Adsorptionsenergie an IL‐Kationen, wodurch ihre Möglichkeit, Li+‐Sprungstellen zu besetzen, reduziert wird. Die deutlich höhere Dielektrizitätskonstante von PTC als PVDF erleichtert die Dissoziation von Li‐Anionen‐Clustern. Diese beiden Faktoren verstärken den Li+‐Transport entlang von PTC‐Ketten, wodurch der Unterschied des Li+‐Transports zwischen den verschiedenen Phasen verringert wird. Die LiFePO4/PTC iono‐SPE/Li‐Zellenzyklen stabil mit einer Kapazitätserhaltung von 91.5 % nach 1000 Zyklen bei 1 C und 25 °C. Diese Arbeit ebnet einen neuen Weg zur Erzeugung eines gleichmäßigen Li+‐Flusses in iono‐SPEs durch Optimierung der Polarität und Dielektrizität der Polymermatrix.

High Dielectric Poly(vinylidene fluoride)-Based Polymer Enables Uniform Lithium-Ion Transport in Solid-State Ionogel Electrolytes.

Ionic liquids (ILs)-incorporated solid-state polymer electrolytes (iono-SPEs) have high ionic conductivities but show non-uniform Li+ transport in different phases. This work greatly promotes Li+ transport in polymer phases by employing a poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE), PTC] as the framework of ILs to prepare iono-SPEs. Unlike PVDF, PTC with suitable polarity shows weaker adsorption energy on IL cations, reducing their possibility of occupying Li+ -hopping sites. The significantly higher dielectric constant of PTC than PVDF facilitates the dissociation of Li-anions clusters. These two factors motivate Li+ transport along PTC chains, narrowing the difference in Li+ transport among varied phases. The LiFePO4 /PTC iono-SPE/Li cells cycle steadily with capacity retention of 91.5 % after 1000 cycles at 1 C and 25 °C. This work paves a new way to induce uniform Li+ flux in iono-SPEs through polarity and dielectric design of polymer matrix.

Three-dimensional printing of a high-impact resistant polylactic acid-based ternary polymer blend

Three-dimensional printing of polylactic acid (PLA)-based polymer blends has several benefits, including low cost, dimensional accuracy and tunability of mechanical properties. Although the addition of Polybutylene adipate terephthalate (PBAT) into PLA improves the ductility of the blend, the two polymers are immiscible. This work introduced polymethyl methacrylate (PMMA) into PLA/PBAT blends as a compatibiliser to improve the interfacial interaction between PLA and PBAT phases. PLA/PBAT/PMMA blends were prepared with varying concentrations of PLA, PBAT (10–20 wt%) and PMMA (0–6 wt%) for 3D printing applications. The mechanical and thermal behaviours of the PLA/PBAT/PMMA ternary blends and their suitability for 3D printing were investigated. The thermal properties of the blends were used to determine the 3D printing nozzle temperature and bed temperature. Three-dimensional printing of the polymer blends was carried out using a Bowden extruder 3D printer. Additionally, the compatibilisation effects of PMMA and interfacial interaction of the polymer phases were investigated using SEM analysis.

Acid-Activated Organobentonite-Based Highly Porous Foams via Polymerized High Internal Phase Emulsion: Preparation, Characterization and Machine Learning Prediction

Preparation, characterization, and machine learning prediction of characteristics of acid-treated organobentonite-based highly porous foams via polymerized high internal phase emulsion were reported in this work. The effect of acid-treated organobentonite (AC-BTN) as an inorganic filler on the properties of poly(DVB)HIPE porous foam was experimentally investigated. Incorporating AC-BTN into the continuous phase of the high internal phase emulsion would improve thermal and mechanical properties and also increase the surface area of the resulting materials when compared to the unfilled poly(DVB)HIPE foam. Various amounts of AC-BTN, i.e., 0, 1, 3, 5, 7, and 10 wt.% of AC-BTN, were incorporated into the continuous phase to enhance the properties of poly(DVB)HIPE foam. The surface area and the degradation temperatures (Td) for the series of poly(DVB)HIPE foam filled with AC-BTN increased with increasing filler content from 0 to 10 wt.%. The maximum improvement of mechanical properties was found with the addition of 5 wt.% of AC-BTN into the continuous phase of poly(DVB)HIPE foam. Moreover, the adsorption of CO2 gas by poly(DVB)HIPE foam filled with AC-BTN was found to increase as well. It has been demonstrated in this study that the adsorption of CO2 by poly(DVB)HIPE foam filled with AC-BTN increased by 127% (from 0.00295 to 0.00670 mol/g) compared with neat poly(DVB)HIPE foam. Additionally, the machine learning (ML) method with a linear regression algorithm was employed for the characterization of poly(DVB)HIPE foam and the prediction of properties according to composite composition. Surface area, pore volume, Td, compressive stress, and Young’s modulus were evaluated. The accuracy of prediction using a machine learning application with a linear regression model for properties of poly(DVB)HIPE foam filled with AC-BTN was also reported.

High-pressure phases of BaCN[formula omitted] explored using a genetic algorithm

Nitrogen-containing polymers have attracted considerable research attention for their application to high energy density materials, where the energy is internally stored in their triple bonds. In this regard, it is intriguing to examine whether such polymerized phases appear in the high-pressure phase of metal carbodiimide MCN2, which have been synthesized recently. However, very few studies have investigated crystal structures up to 10/15 GPa in experiments/simulations. In this work, we adopted a structure search based on genetic algorithm coupled with ab initio electronic structure calculations to investigate possible crystal structures that may appear in the high-pressure phase of BaCN2. Furthermore, we reproduced the previously reported crystal structures in the lower pressure range ∼6GPa. With confirmed reliability of its predictive capability, we used the genetic search and predicted a polymerized phase with Ima2 appearing at higher pressure above 42 GPa. The polymerized phase has a linear network structure of CN3 planar triangular units. It has been found that the anion site units CN2, which are close to each other under high pressure, form direct covalent bonds and stabilize the phase.

Trapping of polycyclic aromatic hydrocarbons in vehicle exhaust using an in-tube extraction device for analysis by gas chromatography-barrier ionization discharge detection

This work presents a methodology for polycyclic aromatic hydrocarbons (PAHs) trapping from vehicular emissions using an in-tube extraction device (IT-FEx). Trapping selectivity studies were conducted, evaluating the interaction profile between the aromatic compounds and the polymeric phase (composed of polydimethylsiloxane and internal to the IT-FEx devices), as in an aqueous equilibrium system (25 min of sampling), and as in gaseous dynamic phase (30 s of sampling), regarding a qualitative evaluation. The adsorption profiles were similar, with greater affinity for medium-sized PAHs (four aromatic rings) than for the smaller (one to three rings) and larger (five to six rings). The device was attached to a vehicle emission sampler to evaluate the qualitative emission of diesel-powered vehicles. Certain PAHs, such as phenanthrene, fluoranthene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[k]fluoranthene, were effectively trapped by the IT-FEx device and detected by the GC-BID analysis. Finally, it was possible to develop a process that combined the steps of sample preparation and instrumental analysis, using the IT-FEx device and applying it to the gaseous matrix in the dynamic phase; until then, little was elucidated regarding the use of this apparatus. This sampling device, combined with analysis by gas chromatography with a barrier ionization discharge detector (GC-BID), is a powerful tool for identifying many compounds from vehicular emissions and does not require solvents in sample preparation.

Comparison of olefin/paraffin separation by ionic liquid and polymeric ionic liquid stationary phases containing silver(I) ion using one-dimensional and multidimensional gas chromatography

Silver(I) ions have been used in various studies as components within polymer membranes or ionic liquids (ILs) to enable separation of olefins from paraffins. Polymeric ionic liquids (PILs) are a class of polymers synthesized from IL monomers and typically possess higher thermal and chemical stability than the ILs from which they are formed. Until now, very little is known about the difference in strength of silver(I) ion-olefin interactions when they take place in an IL compared to a PIL. In this work, the chromatographic separation of olefins by stationary phases composed of silver(I) bis[(trifluoromethyl)sulfonyl]imide ([Ag+][NTf2−]) incorporated into the 1-hexyl-3-methylimidazolium NTf2 ([HMIM+][NTf2−]) IL and poly(1-hexyl-3-vinylimidazolium NTf2) (poly([HVIM+][NTf2−])) PIL at varying concentrations was investigated. Olefins were more highly retained by silver(I) ions in PILs than in ILs as the silver(I) salt concentration in the stationary was increased. The potential separation power of silver(I)-containing IL and PIL stationary phases in comprehensive two-dimensional gas chromatography (GC×GC) was compared to the conventional one-dimensional system. The separation selectivity of alkenes and alkynes from paraffins was significantly increased, while dienes and aromatic compounds showed insignificant changes in retention. The chemical structural features of IL and PIL that enhance silver(I) ion stability and olefin separation were investigated by using silver(I) trifluoromethanesulfonate ([Ag+][OTf−]), 1-decyl-3-methylimidazolium NTf2 ([DMIM+][NTf2−]) IL, poly(1-decyl-3-vinylimidazolium NTf2 (poly([DVIM+][NTf2−])) PIL, [HMIM+][OTf−] IL and poly([HVIM+][OTf−]) PIL. Longer alkyl substituents appended to the IL (and PIL) cation increased the strength of silver(I) olefin interaction, and [OTf−] anions in the IL (and PIL) tended to preserve silver(I) ion from thermal reduction, while also retaining olefins less than the [NTf2−]-containing columns. In general, silver(I) ions in PILs possessing analogous chemical structures to ILs exhibited higher silver(I) ion-olefin interaction strength but were less thermally stable.

Design and mathematical modeling of polymeric phases to obtain controlled microporosity materials by 3D printing

Design and mathematical modeling of polymeric phases to obtain controlled microporosity materials by 3D printing

Electrical Conductance Mechanism of Silver-Polyacrylonitrile Nanocomposite Fibers.

This paper presents the mechanism of electrical conductivity in nanocomposite polyacrylonitrile (PAN) fibers modified with silver nanoparticles (AgNPs). Fibers were formed by the wet-spinning method. The nanoparticles were introduced into the polymer matrix as a result of direct synthesis in the spinning solution from which the fibers were obtained, thereby influencing the chemical and physical properties of the polymer matrix. The structure of the nanocomposite fibers was determined using SEM, TEM, and XRD, and the electrical properties were determined using the DC and AC methods. The conductivity of the fibers was electronic and based on the percolation theory with tunneling through the polymer phase. This article describes in detail the influence of individual fiber parameters on the final electrical conductivity of the PAN/AgNPs composite and presents the mechanism of conductivity.

Small Molecules, Great Powers: Chemistry of Small Organo‐Chalcogenide Molecules in Rechargeable Li‐Sulfur Batteries

AbstractSmall organic chalcogenides molecules are receiving more attention in conjunction with the development of rechargeable lithium metal batteries (LMBs) especially lithium–sulfur (Li−S) batteries due to their abundant resources, reversible redox, high capacities, tunable structures, unique functional adjustability, and strong interaction with congener polysulfides. In this review, the working principles are generalized of small organo‐chalcogenide molecules in three important parts of batteries: electrolyte, interface, and cathode. First, in terms of regulating kinetics in electrolyte, small organo‐chalcogenide molecules can not only act as redox mediator to accelerate the redox kinetics of sulfur, but also change the inherently slow solid–solid process to form a faster redox pathway, which will bring light to the development of cryogenic Li−S batteries. Second, for interface chemistry, the introduction of small organo‐chalcogenide molecules can construct more elastic and stable anodic single‐SEI or cathodic/anodic dual‐SEI, thus effectively improving the cycling stability of batteries. Third, small organo‐chalcogenide molecules can be used as cathode materials in the form of liquid phase, solid phase, or precursor of polymers. Finally, advised optimizations are proposed about further mechanism deciphering, battery configuration design, machine learning, thereby providing direction to bridge the gap between rational modulation and practical battery implementation for small organo‐chalcogenide molecules.

Tip-Induced Nanopatterning of Ultrathin Polymer Brushes.

Patterned, ultra-thin surface layers can serve as templates for positioning nanoparticlesor targeted self-assembly of molecular structures, for example, block-copolymers. This work investigates the high-resolution, atomic force microscopebased patterning of 2nm thick vinyl-terminated polystyrene brush layers and evaluates the line broadening due to tip degradation. This work compares the patterning properties with those of a silane-based fluorinated self-assembled monolayer (SAM), using molecular heteropatterns generated by modified polymer blend lithography (brush/SAM-PBL). Stable line widths of 20nm (FWHM) over lengths of over 20000µm indicate greatly reduced tip wear, compared to expectations on uncoated SiOx surfaces. The polymerbrush acts as a molecularly thin lubricating layer, thus enabling a 5000 fold increase in tip lifetime, and the brush is bonded weakly enough that it can be removed with surgical accuracy. On traditionally used SAMs, either the tip wear is very high or the molecules are not completely removed. Polymer Phase Amplified Brush Editing is presented, which uses directed self-assembly to amplify the aspect ratio of the molecular structures by a factor of 4. The structures thus amplified allow transfer into silicon/metal heterostructures, fabricating 30nm deep, all-silicon diffraction gratings that could withstand focused high-power 405nm laser irradiation.

Estimation of the chain propagation rate constants of propylene polymerization and ethylene‐1‐hexene copolymerization catalyzed with MgCl2‐supported Ziegler–Natta catalysts

AbstractIn olefin polymerization with MgCl2‐supported Ziegler–Natta (Z–N) catalysts, the apparent propagation rate constant (kp)a calculated by Rp = (kp)a [C*] CMe (CMe is equilibrium monomer concentration in the reaction system) declines with reaction time for gradually developed monomer diffusion limitation in the polymer/catalyst particles. In this work, a simplified multi‐grain particle model was proposed to build correlation between (kp)a and other kinetic parameters that can be determined experimentally. Rate profiles of propylene polymerization and ethylene‐1‐hexene copolymerization by three MgCl2‐supported Z–N catalysts were determined, and the (kp)a data was calculated using [C*] determined by quench‐labelling the propagation chains with acyl chloride. Decline of (kp)a in each polymerization process was precisely fitted by the linear correlation between lg(kp)a and [(ρcatmp)/(ρpmcat) + 1]1/3 developed on the particle model. Real propagation rate constant (kp) was estimated by extrapolating the fitting line to the starting point of polymerization, where no concentration gradient exists. According to the particle model, the slope of the lg(kp)a versus [(ρcatmp)/(ρpmcat) + 1]1/3 line (lgd) represents the degree of monomer diffusion limitation. Variations of parameter d found in the studied reaction systems can be reasonably explained based on the knowledge of olefin diffusion in the polymer phase.

Suppressing storage-induced degradation of Li7La3Zr2O12 via encapsulation with hydrophobicity-tailored polymer nanolayer

Solid-state batteries have been proposed as an alternative to conventional lithium-ion batteries to resolve safety issues. Biphasic solid electrolytes (BSEs) based on Li7La3Zr2O12 (LLZO) and a polymer phase have been widely studied because LLZO has high Li+ conductivity and chemical/electrochemical compatibility with Li metal. However, LLZO reacts with H2O and CO2 during storage in air, forming lithium carbonate (Li2CO3) layers on the surface. The extremely low Li+ conductivity of Li2CO3 degrades the Li+-conduction properties of LLZO-based BSEs. Herein, we propose an effective approach to improve the air-stability of LLZO via encapsulation with a hydrophobicity-tailored, Li+-conducting polymer nanolayer. Polyurethane-based polymers are designed to have high hydrophobicity by tuning soft segments and chain extenders and successfully encapsulate the LLZO surface with a thickness of ∼10 nm (P-LLZO). Accelerated durability tests (ADTs) under controlled concentrations of O2, H2O, and CO2 indicate that LLZO encapsulation with hydrophobic polymer effectively mitigates storage-induced degradation by preventing direct contact between LLZO and H2O/CO2. ADT-tested P-LLZO BSE exhibits higher ionic conductivity (σ = 1.3 × 10−4 S cm−1 at 60 °C) compared with that of ADT-tested LLZO BSE (σ = 3.6 × 10−5 S cm−1). A solid-state Li battery with ADT-tested P-LLZO BSE shows enhanced cycling stability than that with ADT-tested LLZO BSE, proving the efficacy of polymer encapsulation. The findings are essential for understanding the role of interfacial engineering in mitigating the degradation of Li+-conduction properties and developing highly conductive LLZO-based BSEs.

How Regiochemistry Influences Aggregation Behavior and Charge Transport in Conjugated Organosulfur Polymer Cathodes for Lithium–Sulfur Batteries

For lithium-sulfur (Li-S) batteries to become competitive, they require high stability and energy density. Organosulfur polymer-based cathodes have recently shown promising performance due to their ability to overcome common limitations of Li-S batteries, such as the insulating nature of sulfur. In this study, we use a multiscale modeling approach to explore the influence of the regiochemistry of a conjugated poly(4-(thiophene-3-yl)benzenethiol) (PTBT) polymer on its aggregation behavior and charge transport. Classical molecular dynamics simulations of the self-assembly of polymer chains with different regioregularity show that a head-to-tail/head-to-tail regularity can form a well-ordered crystalline phase of planar chains allowing for fast charge transport. Our X-ray diffraction measurements, in conjunction with our predicted crystal structure, confirm the presence of crystalline phases in the electropolymerized PTBT polymer. We quantitatively describe the charge transport in the crystalline phase in a band-like regime. Our results give detailed insights into the interplay between microstructural and electrical properties of conjugated polymer cathode materials, highlighting the effect of polymer chain regioregularity on its charge transport properties.

Electrical Properties of Polyvinylidene fluoride‐H3PO2 Protonic Conductor; a Novel Electrolyte for Use in Fuel Cells

Polyvinylidene fluoride (PVDF) and hypophosphorous acid (H3PO2) are combined to synthesize solid polymer electrolyte membranes using the solution cast method. Electrochemical impedance spectroscopy measurements are used to find the conductivity, and those values are plotted as a function of relative humidity (% RH) to which the membranes are kept. In agreement with the modified Onsager, the results show growth in conductivity as % RH increases, which states that ionic mobility of a polar polymeric phase increases as levels of absorbed water by the polymeric membrane increase. The high values of conductivity observed at high concentrations of H3PO2 (σ = 9.83 × 10−3 S cm−1 for x = 60% wt) are attributed to the increase of charge carriers and the dissociation of ions in an aqueous phase. The synthesized membranes are tested as electrolytes in a fuel cell and the voltage and power density plotted as a function of the current density with maxim values of the power density of 2.88 mW cm−2 for a 30% wt membrane.

Scalable, Highly Pure, and Diameter‐Sorted Boron Nitride Nanotube by Aqueous Polymer Two‐Phase Extraction (Small Methods 4/2023)

Back Cover In article number 2201341, Sung Gap Im, Yongho Joo, and co-workers demonstrate the successful separation of nanotubular boron nitrides from synthetic mixtures via an aqueous extraction protocol. The method utilizes selective partitions into thermodynamically driven phases of aqueous polymers. The method features simplicity, cost-effectiveness, and scalability, with the resulting product demonstrating a liquid crystalline grade nanotubular assembly.

Ferrofluid double emulsion generation and manipulation under magnetic fields

Magnetically controlled double emulsions offer a promising tool for targeted drug delivery. Here, the effect of a non-uniform magnetic field induced by a permanent magnet on ferrofluid double emulsion generation and morphology is studied. In the numerical part, the double emulsion (and its ferrofluid core) migration was analyzed for different transverse distances of the magnet from the channel centerline (Ly) and different core and shell diameters. In the experimental part, water-based ferrofluid is encapsulated in a UV-curable polymer phase in water, forming a W/O/W double emulsion. As the magnet’s downstream distance from the ferrofluid junction reduces, the core aspect ratio increases while its diameter decreases. Finally, the core eccentricity was calibrated with Ly, and by shining a UV light, this core eccentricity was affixed inside the UV-curable medium. These double emulsions can then rearrange and orient under a uniform magnetic field for more efficient targeted drug delivery.