Polymer Template Research Articles

Preparation of Li+:TiO2 nanowires, Li4Ti5O12 nanotubes, and a Li4Ti5O12 nanotube/graphene composite by single-spinneret electrospinning for application in a lithium-ion battery

A single-spinneret electrospinning method to fabricate Li4Ti5O12 nanotubes and a Li4Ti5O12 nanotube/graphene composite was reported.

Co-substitution in a Prussian blue analog with a hollow heterostructure for ultrahigh capacity and rate capability aqueous Zn2+ batteries.

Nickel and manganese co-substitution into hollow Prussian blue nanocubes (H-PBMN) has been successfully carried out via utilizing a high-concentration polymer template to grow manganese-Prussian blue (PBM) and nickel-Prussian blue (PBN) through a slow nucleation process. Due to the hollow structure and double metal co-substitution, the properties of the electrode material have been optimized, and it presents an ultrahigh capacity of 138.4 mA h g-1 at 0.05 A g-1.

Effect of Pluronic P103 Concentration on the Simple Synthesis of Ag and Au Nanoparticles and Their Application in Anatase-TiO2 Decoration for Its Use in Photocatalysis.

Silver and gold nanoparticles were synthesized under environmentally-friendly reaction conditions by using a biodegradable copolymer and water as a solvent. The triblock copolymer Pluronic P103 was utilized as a stabilizing agent or soft template to produce Ag and Au nanoparticles (NPs) of different sizes. Moreover, in the synthesis of Au NPs, the polymer acted as a reducing agent, decreasing the number of reagents used and consequently the residues produced, hence, rendering the procedure less complicated. It was observed that as the concentration of the polymer increased, the size of the metallic NPs augmented as well. However, AgNPs and AuNPs prepared with 1 and 10 wt% Pluronic P103, respectively, showed a significant decrease in particle size due to the presence of polymeric soft templates. The hybrid materials (metal/polymer) were characterized by UV-Vis spectroscopy, DLS, and TEM. The pre-synthesized nanoparticles were employed to decorate anatase-TiO2, and the composites were characterized by DRS, XRD, BET surface area measurements, the TEM technique with the EDS spectrum, and XPS spectroscopy to demonstrate NPs superficial incorporation. Finally, methylene blue was used as a probe molecule to evidence the effect of NPs decoration in its photocatalytic degradation. The results showed that the presence of the NPs positively affected methylene blue degradation, achieving 96% and 97% removal by utilizing TAg0.1 and TAu10, respectively, in comparison to bare anatase-TiO2 (77%).

1D Nanomaterials in Fe‐Group Metals Obtained by Synthesis in the Pores of Polymer Templates: Correlation of Structure, Magnetic, and Transport Properties

1D cylindrical magnetic nanostructures (FeNi, FeCo, FeCoP) of complex topology such as nanowires (NWs), nanotubes (NTs), multilayered nanowires, and core–shell structures are discussed from the perspective of engineering a wide variety of magnetic materials from hard to semihard to soft. Most of recent data are given for the materials synthesized in the pores of polymer ion‐track membranes, which makes it possible to tune systematically the geometrical parameters, morphology, and composition. The key properties including crystal and micromagnetic structure, magnetic anisotropy, and coercivity are analyzed. Co‐based NWs with uniform morphology demonstrate coercivity of more than 10 kOe due to the combination of crystalline and shape anisotropies. In the case of NTs, the demagnetizing effect is reduced owing to a helical arrangement of the magnetization, which leads to low values of coercivity and remanence magnetization. Varying the geometrical parameters of multilayered NWs, the alternating soft and semihard magnetic layers can be made within a single nanowire, which is important for spin‐valve magnetoresistance. Au‐coated ferromagnetic nanostructures are biocompatible and can be used to enhance optical absorption. Ni@Au NTs used as substrates for Raman spectroscopy demonstrate the enhancement factor of the order of 104. Some aspects related to applications of 1D magnets are briefly overviewed.

Inline Rolling Shear Alignment: Deposition and Long-Range Order of Block Polymer Templates in a Fast, Single-Step Process

We report the first demonstration of a rapid, single-step technique to align block polymer, thin-film nanostructures, which is amenable to continuous speeds of ≥10 mm/s. This method, termed inline rolling shear alignment (IRSA), uses an elastomeric roller coupled with an electric hysteresis brake to shear films before the casting solvent fully evaporates, and it can enable high-throughput, large-area manufacturing of patterns such as nanowire templates. IRSA is adaptable to various polymer systems including diblock and triblock polymers, and a post-shear annealing step can yield high-quality nanostructures with orientation parameters >0.99 and defect densities as low as 5 defect-pairs/μm2. To demonstrate the effectiveness of IRSA, platinum nanowires were produced from this rapid deposition and alignment approach using poly(styrene-b-2-vinylpyridine), followed by open-air, atmospheric-pressure plasma etching. This integrated concept, with 50× faster operation than existing processes, could be leveraged for cost-effective manufacturing of macroscopically aligned nanostructures in roll-to-roll systems.

Hierarchically Inverse Opal Porous Scaffolds from Droplet Microfluidics for Biomimetic 3D Cell Co-Culture

With the advantages of better mimicking the specificity of natural tissues, three-dimensional (3D) cell culture plays a major role in drug development, toxicity testing, and tissue engineering. However, existing scaffolds or microcarriers for 3D cell culture are often limited in size and show suboptimal performance in simulating the vascular complexes of living organisms. Therefore, we present a novel hierarchically inverse opal porous scaffold made via a simple microfluidic approach for promoting 3D cell co-culture techniques. The designed scaffold is constructed using a combined concept involving an emulsion droplet template and inert polymer polymerization. This work demonstrates that the resultant scaffolds ensure a sufficient supply of nutrients during cell culture, so as to achieve large-volume cell culture. In addition, by serially planting different cells in the scaffold, a 3D co-culture system of endothelial-cell-encapsulated hepatocytes can be developed for constructing certain functional tissues. It is also demonstrated that the use of the proposed scaffold for a co-culture system helps hepatocytes to maintain specific in vivo functions. These hierarchically inverse opal scaffolds lay the foundation for 3D cell culture and even the construction of biomimetic tissues.

Polymer templates effects on microstructure and mechanical properties of electrospun mullite nanofibers

Polymer templates are important additives for electrospun ceramic nanofibers and have strong relationship to its properties. In this study, polyvinylpyrrolidone (PVP) and polyvinyl butyral (PVB) were used as templates to prepare mullite nanofibers. The morphology, microstructure and mechanical properties of the nanofibers were investigated and compared. Results show that after 1000 °C calcination, fibers prepared using PVB had a porous structure with surface area of 40.11 m2/g, and were composed of mullite crystals with elastic modulus of ∼27.5 GPa. However, the fibers prepared using PVP had a dense structure with surface area of 8.14 m2/g, and were composed of γ-Al2O3 and mullite crystals with a higher elastic modulus of ∼79.4 GPa. The influence mechanism was confirmed that the different binding states of polymer and aluminasilica precursor were the main reason for the fiber differences. These results give a reference for polymer template categories selection for preparing mullite nanofibers applied in different areas like filtration, catalysis and insulation.

Ammonia vapor induced transformation of selected alkoxysilanes within artificial and natural polymer templates

The article demonstrates the series of silicas produced from various alkoxysilanes introduced into the Amberlite® XAD7HP and lyophilized agar, whose transformation took place in the presence of ammonia vapors as catalyst. The silicas have been investigated by the means of the up-to-date analytical methods for the full characterisation of produced solids including positronium annihilation lifetime spectroscopy. The morphology of the silica is the result of the specific conditions applied for precursors transformation. Usage of lyophilized agar as a template for the vapor-phase method does not lead to creation of highly porous silica. The same applies to SiO2 materials produced without any template, with one except for tetrapropoxysilane. On the contrary Amberlite® XAD7HP is a very effective template. This polymer used as a template allows to obtain porous silica (specific surface area > 300 m2 g−1) in a form of microspheres from each of the employed precursors.

Stimuli-Induced Upgrade of Nuclease-Resistant DNA Nanostructure Composed of a Single Molecular Beacon for Detecting Mutant Genes.

As a kind of cell-free DNA in the bloodstream liberated from tumor cells, circulating tumor DNAs (ctDNAs) have been recognized as promising biomarkers in the field of early cancer diagnosis. However, robust, sensitive, and accurate detection of ctDNA in serum remains extremely challenging, especially toward the mutant KRAS gene, one of the most frequently mutated genes. Although DNA oligonucleotides as emerging practical signaling materials have been developed as sensitive and accurate tools, some intrinsic defects need to be overcome, such as fragility in complex biological environments. In this work, on the basis of the hydrophilicity-promoted assembly, a core/shell DNA nanostructure (DNS-MB) probe is constructed from only one hairpin-shaped probe (cholesterol-modified palindromic molecular beacon, Chol-PMB) for the amplification detection of KRAS mutation in serum without the need for any auxiliary probe. Chol-PMB is designed to recognize target DNA and serve as a polymerization primer and template, and thus target species can initiate polymerization-based strand displacement amplification (SDA). Moreover, target DNA is able to induce further aggregation of DNS-MB particles due to the enzymatic cross-linking effect, leading to a structural upgrade. The DNS-MB probe exhibits a detection limit of 50 fM and a wide quantitative range (from 50 fM to 160 nM). In addition, single nucleotide polymorphisms can be discriminated, such as mutant KRAS G12D (KRAS-M), providing a desirable platform for screening ctDNAs. More excitingly, because the termini of DNA components are hidden inward from nuclease attack, DNS-MB circumvents a false-positive signal even in freshly sampled serum and is suitable for application in the complex biological milieu. As a proof of concept, the DNS-MB probe is expected to provide useful insight into the development of simple and degradation-resistant DNA probes for substantially amplified detection of ctDNAs in complex serum, showing potential applications in the field of early tumor diagnosis.

Gelatin nanoparticles via template polymerization for drug delivery system to photoprocess application in cells

Photodynamic therapy (PDT) is a clinical treatment based on the activation of light-absorbing photosensitizers (PS) to generate reactive oxygen species, which are toxic to the targeted disease cells. Because most PS are hydrophobic with poor water solubility, it is necessary to encapsulate and solubilize PS in aqueous conditions to improve the photodynamic action for this compound. In this work, gelatin-poly(acrylic acid) nanoparticles (PAA/gelatin nanoparticles) via template polymerization for incorporation aluminum chloride phthalocyanine (ClAlPc) as a model drug for PDT application were developed. Biocompatible core-shell polymeric nanoparticles were fabricated via template polymerization using gelatin and acrylic acid as a reaction system. The nanoparticulate system was studied by scanning electron microscopy, steady-state, and their biological activity was evaluated using in vitro cancer cell lines by classical MTT assay. The obtained nanoparticles had a spherical shape and DLS particle size were determined further and was found to be around 170 nm. The phthalocyanine-loaded-nanoparticles maintained their photophysical behaviour after encapsulation. It is found that ClAlPc can be released from the nanoparticles in a sustained manner with a small initial burst release. In vitro cytotoxicity revealed that ClAlPc-loaded nanoparticles had similar cytotoxicity to free ClAlPc with mouse melanoma cancer cell line (B16-F10). In vitro photoeffects assay indicated that the nanoparticle formulation was superior in anticancer effect to free ClAlPc on mouse melanoma cancer cell line B16-F10. The results indicate that ClAlPc encapsulated in gelatin-poly(acrylic acid) nanoparticles are a successful delivery system for improving photodynamic activity in the target tissue.

Rational route to fabrication of uni-dimensional surface gradients presenting stochastic and periodic arrangement of nanoparticles

Nanostructure gradients exhibiting graded variation in a nanostructure geometric variable carry high promise as tool for parallel and high-throughput optimization of a range of on-chip devices and functional interfaces. The capabilities to fabricate nanostructure gradients, with desired size and slope, while preserving scalability and operational flexibility is however limited. In this direction, we demonstrate a simple and flexible approach to prepare nanostructure gradients, subjecting a functionalized chip for the adsorption of nanoparticles or ions from aqueous media, with varying durations of exposure along the length of the chip. The configuration is similar to dip-coating, however, with the solution front moving relative to a stationary substrate. The flow rate, dimension of the chamber, and the functional layers are shown as simple handles to achieve the desired gradient morphology. Gradients with stochastic as well as periodic organization of nanoparticle assemblies are demonstrated through the choice of different functional layers underneath the nanoparticle layer, viz. aminosilane monolayers, cross-linked plasma polymer and copolymer templates. The approach paves way to rationally designed gradients, benefitting from the significant flexibility in the choice of operational conditions, without specific constraints on the size of the substrates that can be used.

Novel anti-oxidation electrochemical sensor based on rod-shaped polyaniline-carboxymethyl cellulose-copper nanoparticles for nitrite determination

In this paper, a new type of copper nanoparticles (Cu NPs) coated with antioxidant film was prepared, and a low-cost nitrite electrochemical sensor was constructed. Low-cost carboxymethylcellulose sodium (CMC-Na) and aniline were used as raw materials, and CMC-Na was used as the polymerization template of aniline to successfully prepare polyaniline-carboxymethyl cellulose nanorods (PANI-CMC). In order to slow down the oxidation rate of copper nanoparticles, [email protected] nanoparticles ([email protected] NPs) containing 2.5 nm antioxidation film were prepared in consideration of the high water solubility, good chemical stability and strong film-forming ability of CMC. It turns out that the prepared [email protected] NPs/GCE had a good current response to nitrite with the linear detection ranges of 3-15,000 μM and 15,000-29,000 μM, and the limit of detection (LOD) of 0.170 μM (S/N= 3). The sensor based on the [email protected] NPs performed good stability and retained 91.3% of the initial sensitivity after 25 days. Meanwhile, the preparation cost of the sensor was extremely low owing to the low price of raw materials in the experiment process, which made mass production possible.

Initial Dynamic Susceptibility of Maghemite Nanoparticles Dispersed in Surface-Treated Polymeric Template.

Magnetic nanocomposites based on maghemite nanoparticles supported (ex situ route) on styrene- divinilbenzene (Sty-DVB) copolymer templates were produced and characterized for their structure and morphology. The as-produced nanocomposites were further chemically-treated with different oxidant agents and surface-coated with stearic acid. X-ray diffraction and transmission electron microscopy data show that the incorporated nanoparticles are preserved despite the aggressive chemical treatments employed. From the dynamical susceptibility measurements performed on the nanocomposites, the values of the saturation magnetization (76 emu/g) and the effective magnetic anisotropy (1.7 × 10⁴ J/m³) were obtained, in excellent agreement with the values reported in the literature for maghemite. This finding strongly supports the preservation of the magnetic properties of the supported nanosized maghemite throughout the entire samples' processing.

Synthesis of Customizable Macromolecular Conjugates as Building Blocks for Engineering Metal–Phenolic Network Capsules with Tailorable Properties

Metal–phenolic networks (MPNs), formed through coordination bonding between phenolic molecules and metal ions, are a promising class of materials for engineering particle systems for diverse applications. However, the properties of such MPNs are inherently restricted due to the finite properties of naturally occurring phenolic molecules. Herein, we report a simple and robust approach to incorporate phenolic moieties into polymers, thereby providing customizable phenolic ligand building blocks that can be used to assemble capsules with a range of tailorable properties. The phenolic ligand building blocks were synthesized via carbonic anhydride coupling to terminal amines, a conjugation approach typically used for peptide coupling but applied herein for functionalizing polymers. The chemistry enabled optimized end-group purity, thus affording a robust and efficient strategy to generate a library of macromolecular poly(ethylene glycol) (PEG) catechol building blocks with different architectures (i.e., 2-, 4-, and 8-arm) and molecular weights (from 2.5 to 20 kDa). The resulting phenolic building blocks were applied to fabricate capsules with shell thickness, permeability, and cell association properties that were controlled via the variation of the macromolecular catechol architecture and molecular weight. Specifically, the shell thickness was varied more than 19-fold (i.e., between ∼9 and 169 nm) by judicious selection of the polymer molecular weight, arm number, and template. Similarly, the permeability of the resulting MPN capsules to 500 kDa dextran was tuned from >90 to <5% by varying the number of arms in the polymer structure while maintaining a constant PEG Mn-to-catechol group ratio. Furthermore, the cell association was reduced by a factor of 2.5 by employing 20 kDa 8-arm PEG instead of 2.5 kDa 2-arm PEG during film assembly. These results demonstrate that the applied macromolecular conjugation approach can be used to customize particle properties, potentially facilitating applications in therapeutic delivery, imaging, separations, and catalysis.

Uniform Fabrication of Hollow Titania Using Anionic Modified Acrylated Polymer Template for Phase Composition Effect as Photocatalyst and Infrared Reflective Coating

Polymer coatings containing thermal blocking and near-infrared (NIR)-reflective pigments have received much attention for their potential applications in energy-saving fields. A drawback of these coatings is sustainability providing similar long-term performance. Surface cleaning is mandatory to remove contaminants that decrease reflectance. In this study, synthesized hollow titania as photocatalyst was used to impart anti-contamination to infrared (IR)-reflective coatings. A TiO2 shell was selectively formed on an anionic polystyrene core, modified by methacrylic acid. According to sintering temperature, the enhancement of light absorption ability and photocatalytic activity as methyl orange decomposition was observed with phase composition change. The methylene blue decomposition reaction, reflectance measurement, and measuring thermal profiling of coated steel confirmed the manifestation of hollow particles to dust degradation characteristics and the enhancement of reflection and thermal shielding.

Synthesis and Characterization of Polymeric Microspheres Template for a Homogeneous and Porous Monolith.

Monolith is an emerging technology applicable for separation, filtration, and chromatography due to its interconnected pore structure. However, the current templates used to form monolith pores are associated with poor heat dissipation, uneven pore size distribution, and relatively low mechanical strength during monolith scale-up. Templates made from polymeric microsphere particles were synthesized via a solvent evaporation technique using different types of polymer (polystyrene, polycaprolactone, polypropylene, polyethylene, and poly (vinyl-alcohol) at varied polymer (10–40 wt%) and surfactant (5–10%) concentrations. The resulting microsphere particles were tested as a monolith template for the formation of homogenous pores. Among the tested polymers, polystyrene at 10 wt% concentration demonstrated good particle morphology determined to around 1.94–3.45 µm. The addition of surfactant at a concentration of 7–10 wt% during microsphere synthesis resulted in the formation of well-shaped and non-aggregating microsphere particles. In addition, the template has contributed to the production of porous monoliths with enhanced thermal stability. The thermogravimetric analysis (TGA) indicated monolith degradation between 230 °C and 450 °C, implying the material excellent mechanical strength. The findings of the study provide insightful knowledge on the feasibility of polymeric microsphere particles as a pore-directing template to fabricate monoliths with desired pore structures.

MgF2-Based Organized Porous Inorganic Nanofluorides as Heterogeneous Catalysts for Fluorination of 2-Chloropyridine

The successful preparation of organized porous inorganic fluorides (OPIFs) with a high specific surface area is demonstrated for MgF 2. For the first time, macroporous MgF 2 OPIFs with a surface area of above 200 m 2 g −1 and mesoporous MgF 2 powder were prepared through the assembly of preformed MgF 2 nanoparticles and homemade polymer templates with a tunable size. These OPIF materials have been fully examined at different synthesis stages by means of powder X-ray diffraction, N 2 sorption, scanning electron microscopy, and transmission electron microscopy analyses and 19 F and 1 H solid-state nuclear magnetic resonance. The relation between the nature, the size, and the amount of polymer template on the porous structure was deeply investigated. The MgF 2 OPIFs present a higher thermal stability under air and F 2 calcination than MgF 2 NPs as the structuration of the OPIF composite considerably slows down the crystallite growth during thermal treatment under air. OPIF materials were evaluated for the first time as heterogeneous catalysts for the fluorination of 2-chloropyridine under HF gas as a fluorinating agent at 350°C. This study evidences catalytic sites with two Lewis acidity strengths (medium and low).

Preparation of double-chain polysiloxane by template polymerization and the coexistence of water repellency and adhesion to glass in its cast film

Preparation of double-chain polysiloxane by template polymerization and the coexistence of water repellency and adhesion to glass in its cast film

Chromoionophoric ligand impregnated mesoporous polymeric optical sensors for the colorimetric quantification of Cu2+ in water samples

In this work, we demonstrate the use of simple, low-cost, benign, and portable solid-state optical sensor material constructed through direct immobilization of chromoionophoric probe onto a porous polymer monolithic template. The fabricated polymer template depicts superior sensing properties such as a high surface area with uniform porous networks, which is suitable for the homogenous dispersion of chromoionophoric probe onto the voluminous cavity of the polymer template. The surface morphological features and the structural analysis of the polymer template are characterized using p-XRD, TEM, SEM, SAED, EDAX, XPS, and N2 isotherm analysis. The impregnation of the probe, 2-(4-(dimethylamino)benzylidene)-N-phenylhydrazine-1-carbothioamide (DABNC) onto the pore surface of the polymer monolith renders superior sensing performance in capturing ultra-trace concentration of Cu2+ ions, which is inferred from a series of visual color transitions (dull white to sap green). The selective naked-eye color recognition is associated with the formation of stable charge-transfer complexes with the chelating sites of the probe molecules with Cu2+ ions. To ensure the effectiveness of ion-sensing, analytical parameters such as solution pH, probe concentration, sensor dosage, temperature, response kinetics, and ion-selectivity amidst matrix ions are systematically optimized. The range of linear response signal is found to be 0–100 μg/L, with a limit of detection and quantification values of 0.15 and 0.56 μg/L, respectively. The used sensor material can be regenerated to its original state, without any loss of its sensing efficacy, up to six regenerative cycles. The practical applicability of the developed sensor is tested using various real water samples, and the analytical data obtained are reliable and reproducible (RSD ≤1.12%, n = 3).

Inert Mask Lithography of Edge Narrowed Graphene Nanoribbons Directly Contacted to Metallic Electrodes

AbstractPatterning graphene into strips with nanometer‐scale widths, i.e. graphene nanoribbons, is an effective approach to customize different properties of the material. Narrowing a large sheet of graphene via conventional top‐down approaches meets the intrinsic resolution limitations of lithography. Process residuals as a result of using sticky polymeric templates may also influence the performance of the eventual device, in addition to altering the chemistry of the ribbons. Here, a facile approach for pattering graphene nanoribbons via an inert metallic mask lithography is reported. The masks are prepared by the microtomy of metallic thin films, embedded within polymeric scaffolds and precisely deposited on top of a graphene monolayer. The inertness of the masks allows the precise narrowing of the graphene under different etching environments, permitting the control over the edge chemistry. Remarkably a mild ultrasonication is enough to remove the mask entirely at the end of the process, without leaving any residue. For electronic applications, however, partial removal of the metallic mask using a laser power, in situ realizes a pair of electrodes, hence avoiding the often difficult issue of electrode alignment. The method proposes a simple and direct approach towards the design of chemically tailored, scalable, and electrically connected graphene nanoribbons.