This study investigates the incorporation of magnetic nanoparticles (MNPs) into a dynamic sorbitol-based vitrimer matrix to develop a recyclable, innovative material for robotic applications that can be both actuated and self-healed by the magnetothermal effects of the MNPs. This magnetic heating behavior under an external alternating magnetic field (AMF) is governed by N & eacute;el or Brownian relaxation processes of the integrated MNPs, predominantly influenced by particle size, shape, and the medium's viscosity. Hereby, the optimal particle size for high heating efficiency was determined through a size-selective synthesis using an additive-assisted hydrothermal method. Besides its function of enhancing the compatibility of the particles within the matrix due to decreased particle-particle interactions, the sorbitol-based additive also serves as a monomer for vitrimer synthesis. The vitrimer material is produced by combining the acetoacetylated monomer with Jeffamine T403 as the amine source. Notably, the nanocomposite exhibits rapid shape memory behavior when AMF is applied, with temperatures reaching up to 112 degrees C, three times faster than simply heating it to room temperature. This approach offers promising pathways for advanced technical systems operated via internal temperature stimuli, thereby minimizing external intervention and maximizing operational reliability in variable thermal environments (e.g., at temperatures below the glass transition).

Anisotropic materials, such as intracellular nanochains in magnetotactic bacteria, exhibit significant potential in biomedicine and technology due to their magnetic, direction-dependent properties. However, their synthesis is limited due to scalability and purification issues. Here, we present an alternative route to bioinspired magneto-responsive nanostructures, specifically chain-like arrangements composed of truncated cubic cobalt-doped ferrite particles. The magnetic nanoparticles are synthesized in an eco-friendly manner via coprecipitation and hydrothermal conversion of silica-coated nanorods with varying shell thicknesses. A distinct relationship emerged between the cobalt-to-iron ratio, nanoparticle dimensions, and mass magnetization, revealing that these parameters increase with silica shell thickness and reaction temperature. When an external magnetic field is applied, the randomly distributed particles align themselves into nanochains, facilitating the determination of the number of particles in both parallel and perpendicular orientations, as calculated from Small-Angle X-ray Scattering analysis. It is observed that the cluster numbers vary in comparison to the dipole-dipole interaction energy and particle size due to the formation of these chain-like structures and bundles. A critical evaluation of the characteristics of both individual particles and chains summarizes their suitability for biomedical applications. One of the factors hindering the biomedical applications of bioinspired magnetic nanochains is the need for alternative synthetic strategies and analytical methods to evaluate chain formation under magnetic fields. Here, the authors present both an environmentally friendly approach to synthesize cobalt-doped ferrite nanoparticles via the hydrothermal conversion of core-shell nanorods, and study their chain arrangements in different directions to the magnetic field.

The combination of gold nanoparticles (Au-NPs) and block copolymer (BCP)-based vinylogous urethane vitrimers leads to advanced nanocomposites where the thermal, mechanical, and thermo-mechanical properties are enhanced without interfering with the formation of vinylogous urethane groups and the transamination in the dynamic polymer network. Photoiniferter reversible addition-fragmentation chain transfer polymerization (photoRAFT) and inverse Turkevich synthesis are used in this work to fabricate the desired BCPs and spherical Au-NPs. The key feature of this synthesis is the integration of Au-NPs into the polymer matrix as fixed parts of the hybrid network, ensuring full recyclability. A wide range of properties can be tuned by variations of gold content, monomers, and BCP architecture. After ligand exchange, network formation, and reprocessing through heat compression, the unique optical properties of Au-NPs are retained, allowing plasmonic heating to trigger the transamination exchange reaction within the materials. As a result, the Au-doped vitrimers can self-heal and exhibit shape-memory shortly after exposure to not only heat but also light. This incorporation of Au-NPs into vitrimers could provide a versatile platform for the development of hybrid materials offering potential applications in coatings, sensors, electronic devices, etc.

Due to their unique combination of magnetic and plasmonic properties, magneto-plasmonic nanoparticles (MP-NPs) are engaging platforms for multi-responsive materials. While the magnetic and plasmonic properties can be tuned by different synthesis methods that yield different particle compositions and morphologies, the possibilities of adding responsive properties by embedding MP-NPs in smart polymer matrices have not been extensively explored. This work presents the synthesis and characterization of a magneto-plasmonic CoFe2O4@Au@Polymer hybrid material using a double thermo-responsive graft copolymer. The polymers were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, using their trithiocarbonate (TTC) end group as an anchoring group on the particles’ surface. The colloidal hybrid material was crosslinked to prepare multi-responsive hydrogels, and the presence of the MP-NPs' magnetic and optical properties and the gel's temperature-dependent swelling behavior were explored. To show the synergy of the components, photothermal heating with near-infrared (NIR) irradiation was investigated to reveal that significant amounts of water can be expelled from the hydrogel.Furthermore, the approach of using MP-NPs and TTC-terminated polymers as bases for multi-responsive materials can be adapted to obtain materials with different polymer structures to tailor transition temperatures and surface functionalization. This versatility of the properties, in combination with the heat generation capabilities and the possibility to release water and additional substances dispersed in the water phase, make such hybrid materials interesting for various applications like delivery or targeted release applications.

Crown ether (CE) functionalized polystyrene-block-poly(methacrylic acid) (PS-b-PMAA) material (PS-b-P(MAA-r-CE3MA)) forms lithium-CE sandwich complexes with high selectivity. The complexation strength of PS-b-P(MAA-r-CE3MA) was determined in a two-phase extraction. A two-step one-pot RAFT polymerization in water was used to synthesize the block copolymers, in which the macro-RAFT agent (PMAA) produced in the first step was polymerized with styrene in an emulsion polymerization in the second step. Subsequently, the MAA block was partially esterified with the functionalized CE. The polymer structure was varied for investigating the influence of the degree of polymerization (DP) of the overall polymer, the DP of the PS, and the functionalization density with regard to increasing the effectiveness of lithium complexation. Based on the observed trends, it was possible to optimize the system toward a significantly improved lithium complexation compared to free CE (by a factor of up to 4 x 10(8)).

Truncated octahedral cobalt ferrite-based nanoparticles were synthesised using a precursor-derived coprecipitation reaction followed by a hydrothermal step. The nanoparticles were characterised regarding their shape anisotropy and size distribution as a function of reaction parameters such as time, temperature, metal salt concentration, base molarity, pressure, and reactor filling volume. Notably, temperature and molarity serve as critical synthesis factors that reduce the polydispersity of the particles to values below 0.1, which is an exceptionally favourable result compared to aqueous coprecipitation reactions. Furthermore, an increase in filling volume resulted in higher proportions of coffin-like nanoparticles due to alterations in flow velocity. The crystallographic assignment of the nanoparticle facets was analysed using high-resolution transmission electron microscopy, selected area diffraction, and angle-resolved scanning electron microscopy measurements. This analysis revealed that the {222} facet exhibited preferential growth in the coffin-like particles. By elucidating the significant reaction parameters for enhanced shape anisotropy, it is possible to increase the magnetic anisotropy constants by assuming a prolate spheroid structure with uniaxial shape combined with cubic magnetocrystalline anisotropy. Contributions of the strain and surface anisotropy are discussed briefly to ensure a comprehensive overview.

In recent years, stimuli-responsive poly(ionic liquids) (PILs) have attracted great attention. The stimuli-dependent properties, particularly the electrical properties, of multiresponsive PILs incorporating functionalized nanoparticles, however, have been less investigated. In this work, we present the synthesis, characterization, and application of PIL films incorporating pH- and thermoresponsive hybrid materials composed of gold nanoparticles functionalized with poly(2-(dimethylamino)ethyl methacrylate) (Au@PDMAEMA). The Au@PDMAEMA nanoparticles exhibit distinct responsiveness to changes in environmental pH and temperature, thereby altering the electrical properties of the PIL films blended with responsive gold nanoparticles (PIL w/Au). This research not only fills a gap in the study of electrical properties of multiresponsive nanoparticle-incorporated PILs but also extends the potential applications of PILs in various fields, including smart sensors and electronic devices.

Magnetic CoxFe3-xO4 nanoparticles (NPs, 0.2 < x < 0.5) were prepared by a two-step synthesis of cigar-shaped akaganeite precursors and subsequently conversion through hydrothermal reaction with various molar ratios of Co2+/Fe2+/Fe3+ chloride salts. Both steps were successfully conducted in aqueous media without using toxic surfactants and solvents. To explore the effect of cobalt ion amounts, magnetic and hyperthermia measurements were investigated in dependency on the size, shape, and composition of the samples. Cubic and spherical CoxFe3-xO4 NPs showed an increasing saturation magnetization of up to 68 Am-2/kg with the cobalt ion amount and pressure of the synthesis. The temperature induced by hyperthermia rises up to 9.9 K within 10 min (10 kHz, 24.4 mT), ensuring medical applications such as medical imaging and cancer treatment. The temperature change was increased to 43 K/10 min (150.5 kHz, 19.0 mT) without exceeding the biological limit for nonselective heating. The specific absorption rate of up to 183 W/g(Co+Fe) of the NPs with x = 0.38 is 30% higher than that of near-stoichiometric cobalt ferrite NPs with x = 0.80 synthesized by coprecipitation. The reduction of the cobalt content by up to 52% did not affect the hyperthermia values negatively and enables a greener synthesis method.

This work presents new anisotropic growth-directing copolymers suitable for the seed-mediated growth of gold nanorods (GNRs). Copolymers with different architectures are studied. They all contain dimethylaminomethyl methacrylate (DMAEMA) functionalized with 1-bromohexadecane (BHD) as the vital component. For the synthesis of the different copolymers, the photo-iniferter reversible addition-fragmentation chain transfer (photoRAFT) polymerization is used, where DMAEMA is combined with a lower critical solution temperature (LCST) polymer block for better solubility after the functionalization. The results show that the presented copolymers can induce anisotropic growth of gold nanoparticles. Additionally, the influence of the LCST of the water-soluble block and the temperature of the growth solution on the GNR synthesis are investigated. Furthermore, the plasmonic behavior of the resulting GNRs solution is investigated at temperatures around the LCST of the copolymer. Dimethylaminoethyl methacrylate (DMAEMA)-based copolymers showing a lower critical solution temperature (LCST) are presented, which allow anisotropic growth of gold nanoparticles at a reduced concentration of highly toxic cetyltrimethylammonium bromide (CTAB) of 99% within the growth solution of a seeded-growth approach. Due to the LCST of the copolymer matrix, the gold nanorods show a temperature-dependent plasmon shift in UV-vis spectra. image

Using well-established measurement techniques like transmission electron microscopy (TEM), dynamic light scattering (DLS), small and wide angle X-ray scattering (SAXS, WAXS), susceptometry, and magnetorelaxometry, the distribution of the physical and magnetic size (magnetic moments) and magnetic anisotropy of a variety of structurally different magnetic nanoparticle samples (MNPs) is analyzed and compared. A term which accounts for the presence of weak magnetic areas (WMAs) within the MNPs was introduced to the widespread analysis model for M(H) data, enabling a consistent interpretation of the data in most of the systems. A comparison of the size distributions as obtained for the physical and the magnetic diameter suggests a multidomain structure for three single core systems under investigation, in all probability evoked by the presence of a wustite phase, as identified by WAXS.Analyzing the relationship d < dm < dc between the average single core diameter d, the effective magnetic (domain) size dm and the cluster diameter dc quantitatively, two qualitatively different magnetic structures in multicore MNP (MCMNP) systems were identified: (i) The magnetic moments of single cores within the MCMNP of fluidMAG tend to build flux closure structures, driven by dipole-dipole interaction. (ii) The magnetic behavior of Resovist & REG; was attributed to the presence of domain sizes of about 12 nm within MCMNP, exceeding the single core diameters of 5 nm. Thereby, WAXS revealed a bimodal crystallite size distribution suggesting a crystallite merging process within the MCMNP. The value of the effective magnetic moment of these MCMNP could be explained within the presented "random moment cluster model" (RMCM).We conclude that the combination of physical and magnetic structure parameters obtained from complementary measurement methods allows a reliable assessment of the magnetic structure of single and multicore MNPs.

Combining gold nanoparticles (GNP) with stimuli-responsive polymers is a fascinating field for applications as sensor materials or in biomedical applications. The synthesis of multiresponsive Au@Polymer hybrid systems in an in situ approach using tailor-made poly(2-(dimethylamino)ethyl methacrylate) (P(DMAEMA)) precursor synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization is introduced. In particular, because of its multiresponsive behavior, P(DMAEMA) is of great interest and is used as the precursor for the synthesis. For the polymerization of the precursor, an approach is introduced that applies the photoiniferter RAFT (photoRAFT) mechanism applicable for tertiary amine-bearing methacrylic monomers like DMAEMA. By varying the chain transfer agents (CTA), the influence of different RAFT Z-groups on the solubility of the Au-hybrids is studied. Aging effects are observed by transmission electron microscopy (TEM) analyses. A comprehensive dynamic light scattering (DLS) study reveals the thermoresponsive behavior of the Au-hybrids in an aqueous solution. The influence of free polymer in solution on the suspension stability is observed. The capability of crosslinking using 1,5-dibromopentane (DBP) and the CO2 sensitivity of the synthesized hybrids expands the area of their potential application.

The paper addresses coupling of magnetic nanoparticles (MNPs) with the polymer matrix of temperature-sensitive microgels and their response to magnetic fields. Therefore, CoFe2O4@CA (CA = citric acid) NPs are embedded within N-isopropylacrylamid (NIPAM) based microgels. The volume phase transition (VPT) of the magnetic microgels and the respective pure microgels is studied by dynamic light scattering and electrophoretic mobility measurements. The interaction between MNPs and microgel network is studied via magnetometry and AC-susceptometry using a superconducting quantum interference device (SQUID). The data show a significant change of the magnetic properties by crossing the VPT temperature (VPTT). The change is related to the increased confinement of the MNP due to the shrinking of the microgels. Modifying the microgel with hydrophobic allyl mercaptan (AM) affects the swelling ability and the magnetic response, i.e. the coupling of MNPs with the polymer matrix. Modeling the AC-susceptibility data results in an effective size distribution. This distribution represents the varying degree of constraint in MNP rotation and motion by the microgel network. These findings help to understand the interaction between MNPs and the microgel matrix to design multi responsive systems with tunable particle matrix coupling strength for future applications.

AbstractPolyethersulfonbasierte Hohlfasermembranen mit einer hydrophil funktionalisierten Trennschicht wurden hergestellt und untersucht. In die Trennschicht wurde ein amphiphiles Triblockcopolymer mit verschiedenen Konzentrationen integriert. Um eine gesteigerte Hydrophilie und damit assoziiertes verringertes Fouling zu erreichen, bestehen die Blockcopolymere aus zwei äußeren Poly(ethylenoxid)‐Blöcken. Diese flankieren den inneren Polyethersulfonblock, welcher der Verankerung des Additivs in die Membran dient. Gesteigerte Hydrophilie, gepaart mit Permeanzen von 2000 L m−2h−1bar−1 und einem Rückhalt von 100 kDa, kennzeichnete die vielversprechendste Membran dieser Studie.

Abstract Multi responsive hydrogels have many potential applications in the field of medicine as well as technical fields and are of great interest in fundamental research. Here we present the synthesis and characterization of tailored magnetic hydrogels – micro- as well as macrogels – which consist of iron oxide and cobalt ferrite, varying in phase and morphology, embedded in a thermoresponsive polymer. We introduce new ways to synthesize magnetic particles and revisit some common strategies when dealing with particle synthesis. Subsequently we discuss the details of the thermoresponsive matrix and how we can influence and manipulate the thermoresponsive properties, i.e. the lower critical solution temperature. Ultimately, we present the particle-hydrogel composite and show two exemplary applications for particle matrix interactions, i.e. heat transfer and reorientation of the particles in a magnetic field.

Dual layer hollow fiber membranes, based on poly(ether sulfone), were fabricated to achieve hydrophilic membranes with improved fouling resistance. A new triblock copolymer, consisting of two hydrophilic poly(ethylene oxide) blocks and an inner poly(ether sulfone) block, was chosen for the functionalization of the inner layer. The most promising membrane of this study was characterized by an improved hydrophilicity, and a performance in the ultrafiltration studies of 2000 L m(-2)h(-1)bar(-1) and retention of 100 kDa.

Goethite is a naturally anisotropic, antiferromagnetic iron oxide. Following its atomic structure, crystals grow into a fine needle shape that has interesting properties in a magnetic field. The needles align parallel to weak magnetic fields and perpendicular when subjected to high fields. We synthesized goethite nanorods with lengths between 200 nm and 650 nm in a two-step process. In a first step we synthesized precursor particles made of akaganeite (β-FeOOH) rods from iron(III)chloride. The precursors were then treated in a hydrothermal reactor under alkaline conditions with NaOH and polyvinylpyrrolidone (PVP) to form goethite needles. The aspect ratio was tunable between 8 and 15, based on the conditions during hydrothermal treatment. The orientation of these particles in a magnetic field was investigated by small angle X-ray scattering (SAXS). We observed that the field strength required to trigger a reorientation is dependent on the length and aspect ratio of the particles and could be shifted from 85 mT for the small particles to about 147 mT for the large particles. These particles could provide highly interesting magnetic properties to nanocomposites, that could then be used for sensing applications or membranes.

In this study, we focus on membranes of polyethersulfone and poly(N-vinyl pyrrolidone) and elucidate the influence of composition on the rheological, diffusion and precipitation properties of solutions which are used for membrane preparation via a non-solvent-induced phase separation process. The low-molar-mass component of the solution is a mixture of the solvent N-methyl-2-pyrrolidone and the non-solvent glycerol. Cloud point, viscosity and diffusion measurements as well as precipitation experiments were performed in order to achieve a comprehensive understanding of the time dependence of the precipitation process. The addition of glycerol yields an increase of viscosity and a stronger tendency for demixing. The enhanced tendency for demixing causes a more rapid precipitation process. The average relaxation time of the solution as a function of glycerol concentration follows a similar trend to its viscosity. The increase of viscosity is associated with the increase of the monomeric friction coefficient. Two diffusive processes with clearly separated time scales appear in dynamic light scattering experiments in the presence of glycerol. This phenomenon is discussed taking into account the phase behaviour of the solution and the quality of the solvent. The addition of glycerol yields a lower pure water permeance whereas the molecular weight cut-off is not altered in the ultrafiltration range. (c) 2020 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The ability to deliver two coherent X-ray pulses with precise time-delays ranging from a few femtoseconds to nanoseconds enables critical capabilities of probing ultra-fast phenomena in condensed matter systems at X-ray free electron laser (FEL) sources. Recent progress made in the hard X-ray split-and-delay optics developments now brings a very promising prospect for resolving atomic-scale motions that were not accessible by previous time-resolved techniques. Here, we report on characterizing the spatial and temporal coherence properties of the hard X-ray FEL beam after propagating through split-and-delay optics. Speckle contrast analysis of small-angle scattering measurements from nanoparticles reveals well-preserved transverse coherence of the beam. Measuring intensity fluctuations from successive X-ray pulses also reveals that only single or double temporal modes remain in the transmitted beam, corresponding to nearly Fourier transform limited pulses.

In this study, a triblock copolymer was used as additive to fabricate new dual layer hollow fiber membranes with a hydrophilic active inner surface in order to improve their fouling resistance. The polymeric components of the solutions for membrane fabrication were poly(ether sulfone), poly(N-vinyl pyrrolidone), and the triblock copolymer. The additive consists of three blocks: a middle hydrophobic poly(ether sulfone) block and two outer hydrophilic alkyl poly(ethylene glycol) blocks. By varying the additive concentration in the solutions, it was possible to fabricate dual layer hollow fiber membranes that are characterized by a hydrophilic inner layer, a pure water permeance of over 1800 L/(m2 bar h) and a molecular weight cut-off of 100 kDa similar to commercial membranes. Contact angle and composition determination by XPS measurements revealed the hydrophilic character of the membranes, which improved with increasing additive concentration. Rheological, dynamic light scattering, transmission, and cloud point experiments elucidated the molecular interaction, precipitation, and spinning behavior of the solutions. The low-molecular weight additive reduces the solution viscosity and thus the average relaxation time. On the contrary, slow processes appear with increasing additive concentration in the scattering data. Furthermore, phase separation occurred at a lower non-solvent concentration and the precipitation time increased with increasing additive content. These effects revealed a coupling mechanism of the triblock copolymer with poly(N-vinyl pyrrolidone) in solution. The chosen process parameters as well as the additive solutions provide an easy and inexpensive way to create an antifouling protection layer in situ with established recipes of poly(ether sulfone) hollow fiber membranes. Therefore, the membranes are promising candidates for fast integration in the membrane industry.