Water-soluble Template Research Articles

One-step green synthesis of N-doped hierarchical porous carbon from glycine for high-performance symmetric supercapacitor

N-doped hierarchical porous carbon (NHPC) was facilely fabricated by a one-step pyrolysis of glycine and water-soluble Na2CO3, which is employed as a renewable water-soluble template without additional corrosive activating reagent. Benefiting from the hierarchical porous structure, high specific surface area (2735 m2 g−1) and the suitable nitrogen content of 3.84 at%, the obtained porous carbon exhibits a high specific capacitance (Csp) of 267 F g−1 at 0.2 A g−1 in a three-electrode system and 201 F g−1 at 0.2 A g−1 in the symmetric supercapacitor. More importantly, it shows an impressive rate capability of 102 % retention at 20 A g−1, outstanding cycling stability with 99.95 % of capacitance retention at 5 A g−1 after 10,000 cycles and a high energy density of 28.8 Wh kg−1 at a power density of 20 KW kg−1 in the symmetric supercapacitor. The results indicate that the synthesized NHPC obtained from this simple synthesis method would be an effective electrode material for symmetric supercapacitors, and this eco-friendly and easily scaled-up approach would provide a valuable strategy for the synthesis of porous carbon materials.

Synthesis, characterization, and photophysical and fluorescence sensor behaviors of a new water-soluble double-bridged naphthalene diimide appended cyclotriphosphazene.

A new water-soluble template of double-bridged naphthalene diimide appended cyclotriphosphazene was prepared, and its photophysical and sensor behaviors were evaluated. The characterization of novel double-bridged naphthalene diimide appended cyclotriphosphazene (6) was carried out by NMR (1H, 13C, 31P) and mass spectroscopies. The photophysical behaviors of compound 6 were evaluated by UV-Vis absorption and fluorescence spectroscopies in various solvent systems and different concentrations. As an application for usability of the obtained water-soluble template in different applications, the fluorescence sensor property of compound 6 was investigated in the presence of many different competing species (organic acids, saccharides, nitroaromatic compounds, anions, and metal cations). The results obtained showed that compound 6 had selectivity against only the nitroaromatic species among the competing species tested.

Alpha-calcium sulfate hemihydrate used as a water-soluble template for the synthesis of ZnO hollow microspheres

This work develops α-HH microspheres into a water-soluble template for the green synthesis of hollow-architecture catalysts.

Synthesis of two-dimensional hematite and iron phosphide for hydrogen evolution

Ultrathin α-Fe2O3 and FeP are synthesized by engineering the lattice matching degree between water-soluble template and target material for hydrogen evolution reaction.

Pseudomonas aeruginosa USM-AR2/SiO2 biosorbent for the adsorption of methylene blue

A novel biosorbent (RHA-PA) for the adsorption of methylene blue (MB) was developed by immobilizing deactivated Pseudomonas aeruginosa USM-AR2 (PA) cells on mesoporous rice husk ash silica (RHA-SiO2). The RHA-SiO2 was synthesized via sol-gel method with fructose as a water-soluble template. The highest Brunauer-Emmett-Teller (BET) surface area (601 m2 g−1) determined from N2 adsorption-desorption analysis was achieved when 20 wt% of fructose was added. The Fourier-transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) indicate that the PA cells are chemically bonded to the surface of the silica via its surface silanol groups and also deposited in the voids in between the silica particles. Batch biosorption studies were conducted on RHA-PA under different operational parameters (solution pH, initial dye concentrations, contact time and temperature). The biosorption is best described by the Freundlich isotherm and pseudo-second-order kinetic models since it showed better fitting and higher coefficient of determination (R2 > 0.98 in most of the cases). The maximum biosorption capacities, qmax for MB was 75.7 mg/g, higher than those of other cell biomass reported in the literature. The findings of this study indicate that RHA-PA has the potential as a low-cost and a green biosorbent for the remediation of MB dye.

Maleimide-Modified Gold Nanoparticles (AuNPs): A Versatile ­Platform for Interfacial Click Reactions Leading to Chemically Modified AuNPs

The maleimide moiety can undergo a wide variety of organic reactions, including Diels–Alder reactions, dipolar cycloadditions, and Michael-type additions, making it a suitable moiety for further elaboration of the functionality at the interface of gold nanoparticles (AuNPs) through key reactions that are useful in a host of applications. This account will cover: (1) our approach to prepare maleimide-AuNPs, (2) our survey of the scope of the reactivity of organic-solvent-soluble maleimide-AuNPs, which are very slow, impractical, and required the development of high-pressure techniques in AuNP chemistry yielding dramatic results, and (3) the extension of these ideas to prepare water-soluble small AuNPs to expand the scope of the organic transformation to aqueous environments. Within each of these sections there were challenges that had to be overcome, and we will describe the evolution of the ideas so that readers can get a glimpse of our thinking and problem solving as we proceeded. 1 Introduction 2 Maleimide-AuNPs: The Synthetic Strategy 3 Reactivity of the Organic-Solvent-Soluble Maleimide-AuNP Template 4 Synthesis of the Water-Soluble Maleimide-AuNP Template 5 Reactivity of the Water-Soluble Maleimide-AuNP Template 6 Concluding Remarks

Large-scale synthesis of highly porous carbon nanosheets for supercapacitor electrodes

Two-dimensional (2D) porous carbon nanosheets were synthesized by a facile, low-cost, and scalable method. In this method, glucose was used as a carbon precursor and sodium chloride was employed as a water soluble template. The highly porous carbon nanosheets were prepared by the carbonization of glucose and sodium chloride and the following KOH chemical activation. The as-prepared carbon nanosheets (ACs-NaCl) have a thickness of less than 100 nm. The porous microstructure shows that the porosity of ACs-NaCl consists of essentially micropores with average pore size of ∼0.8 nm. In addition, they possess a large specific surface area up to 2266.6 m2 g−1, which is much higher than that of activated carbons (ACs) obtained without adding NaCl (1036.77 m2 g−1). The ACs-NaCl electrode exhibits a high specific capacitance of 384 F g−1 at the current density of 0.1 A g−1, excellent rate capability and good cycling durability in 6 M of KOH electrolyte. The enhanced capacitive performance of the ACs-NaCl electrode can be attributed to its unique structure that allows the short diffusion paths of electrolyte ions.

Confined crystallization of drug in directionally freeze-dried water-soluble template

The applicability of confined crystallization is limited by the use of extra template materials unsuitable for oral dosage forms. In consideration of this limitation, mannitol was processed into a template with well controlled pores. This template was used for the subsequent confined crystallization of a model drug, resulting in drug/mannitol composite powders processable into the common operations of oral solid dosage forms. The confined crystallization produced a significant melting point depression, caused by a significant particle size reduction, but did not alter the crystal polymorphism. The in vitro release of drug was significantly improved by the confined crystallization.

Hierarchical porous carbon with graphitic structure synthesized by a water soluble template method

Hierarchical porous carbon (HPC) materials with graphitic structure, which exhibit an interesting highly developed three-dimensional porosity network of macropores in combination with meso-/micropores, have been synthesized by a water soluble template (NaCl) method combined with a metal-assisted catalytic technique at 850°C. The soluble NaCl was used as a meso-porous and/or micro-porous structure-directing template, while glucose and Fe species were employed as carbon precursor and graphitization catalyst, respectively. Nitrogen adsorption–desorption analysis showed that with increasing the mole ratio between the metal precursor and the carbon precursor from 0.005 to 0.02, the Brunauer–Emmett–Teller surface area of the HPC samples varied from 498 to 253m2/g.

Assembly of biomacromolecule loaded polyelectrolyte multilayer capsules by using water soluble sacrificial templates

In the quest for greater control over biomacromolecular loading and higher encapsulation efficiencies for biomacromolecule loaded microcapsules we devised a novel approach employing water soluble sacrificial templates. In traditional layer by layer (LbL) methods, aqueous solutions of polyelectrolyte salts in combination with water insoluble sacrificial template materials are used to prepare polyelectrolyte microcapsules that can be loaded with biomacromolecules. Here, we replaced the aqueous phase with pure aliphatic alcohols (Reversed-Phase) to greatly enhance the retention of biomacromolecular cargo close to 100% during microcapsule preparation in this Reverse-Phase Layer by Layer (RP-LbL) process. Formation of stable multilayered polyelectrolyte membranes onto water soluble template materials by sequential deposition of polystyrenesulfonic acid (PSS) and polyallylamine (PA) from pure 1-butanol is reported for the first time. The challenge to exert control over the biomacromolecule concentration within the template material and the resulting microcapsules was addressed by sacrificial template materials. Sacrificial template materials are water soluble and comprise of biomacromolecules embedded into a matrix of small molecular weight molecules such as glucose. Control over the concentration of biomacromolecules in the template material and microcapsules is conveniently exerted by adjusting weight ratios of bimacromolecules to sacrificial template material. This approach is envisioned to be applied alternatively to traditional polyelectrolyte microcapsule preparation techniques in cases where minute losses of expensive biomacromolecules are unfavorable or when accurate control over biomacromolecule concentration is important.

Preparation of D-phenylalanine imprinted microbeads by the modified suspension polymerization using a magnetic impeller

Molecularly imprinted polymeric microbeads (MIPMs) were prepared by using a magnetic impeller by the modified suspension polymerization method with D-phenylalanine (Phe) as the water-soluble template without derivatization, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, toluene as the porogen, polyvinyl alcohol as the stabilizer, and sodium dodecyl sulfate as the surfactant. The mean diameter of MIPMs decreased from 12.45 μm to 8.86 μm by using a simple magnetic impeller instead of a conventional simple straight-blade turbine impeller during suspension polymerization. The adsorption selectivity of MIPMs prepared with a magnetic impeller was much improved as compared to the adsorption selectivity of MIPMs prepared with a conventional simple straight-blade turbine impeller. The adsorption selectivity of MIPMs changed from reversed adsorption (less than 1) to positive (higher than 1) as the washing time increased after suspension polymerization.

Separation of phenylalanine racemates using d-phenylalanine imprinted microbeads as HPLC stationary phase

A successful enantioseparation of d, l-phenylalanine (Phe) was achieved for the first time by using d-Phe imprinted P(MAA-co-EGDMA) microbeads as HPLC stationary phase. The d-Phe imprinted microbeads were prepared by a novel modified suspension polymerization method without derivatization of the water-soluble template molecule. This preparation method was employed in order to capture template molecules in organic phase droplets during polymerization. The prepared d-Phe imprinted P(MAA-co-EGDMA) microbeads were packed into an empty stainless steel column, which was used for the separation of the Phe enantiomers. The selection of a suitable mobile phase, mobile phase composition, pH and flow rate were investigated for determining the best resolution of the Phe enantiomers. Baseline separation was achieved using an organic–aqueous buffer (EtOH–acetate buffer) solution as a mobile phase. Separation factors of more than 2.56, with a resolution of 1.38, were obtained with a mobile phase containing 9–18% (v/v) EtOH in a 0.030 M acetate buffer solution. d-Phe imprinted microbeads were superior to the majority of the reported molecularly imprinted polymers with respect to chiral separation abilities. The column backpressure was less than 300 psi.

Reverse-Phase LbLEncapsulation of Highly Water Soluble Materials by Layer-by-Layer Polyelectrolyte Self-Assembly

We report on a novel method for the encapsulation of highly water soluble materials by using layer-by-layer (LbL) polyelectrolyte self-assembly. State of the art polyelectrolyte self-assembly LbL coating and encapsulation methods are only applicable to insoluble or poorly water soluble template materials, because the process is performed in water causing dissolution of the solid template. Our method extends the material spectrum to highly water soluble template materials by using non-ionized polyelectrolytes in an organic phase (reverse-phase) instead of polyelectrolyte salts in an aqueous environment. By using the reverse-phase layer-by-layer (RP-LbL) technique, we have demonstrated the direct encapsulation of proteins, glucose, vitamin C, and inorganic salts in the solid state. Multilayer deposition was proven, layer thickness was determined by AFM, and the advantage of the method to prepare powders of encapsulated materials was demonstrated. The method is simple, robust, and applicable to a broad range of substances with potential applications in several industries.

Planarizing Surface Topography by Polymer Adhesion to Water-Soluble Templates with Replicated Null Pattern

Water-soluble polymer templates are replicated from flat master surface patterns by spin-casting a poly(vinyl alcohol) film-forming solution that solidifies at standard ambient conditions in less than 1 min. The fabricated water-soluble templates are coupled to substrates with surface topography by polymer adhesion with an intervening reactive or photocurable liquid layer. After curing, the resulting two-layer solid structure is subjected to water thereby dissolving the soluble template to expose the underlying polymer adhesive layer with flat surface topography. The results demonstrate a reduction of surface topography from several micrometers to less than 100 nm. The chemical interactions involved in bonding the soluble template to the polymer adhesive and then dissolving are measured by Raman spectroscopy to demonstrate that the constituents comprising the water-soluble template are absent from the surface of the planarization material.

Molecular transfer lithography for pseudomaskless, high-throughput, aligned nanolithography

A class of high-resolution printing methods, collectively called molecular transfer lithography (MxL), involves the replication of surface patterns as water-soluble templates. The templates are manufactured by spin-casting a polyvinyl alcohol (PVA) film-forming solution on a master pattern. The resultant water-soluble templates are then bonded to the substrate using an intervening adhesive layer that solidifies through photocuring, thermal, or two-part reactive schemes. The templates are chemically removed by dissolution with water yielding a formed pattern in the adhesion layer. Other variations of MxL include the transfer of materials to the substrate such as metals deposited on the template surface. For higher quality prints and overlay, contact alignment tools for MxL are needed. This article describes the implementation of MxL transfer schemes by adaptation of standard contact aligners normally used for photolithography. The primary modification required for integration is the replacement of the quartz photomask with the conformable water-soluble template. Results are presented to demonstrate the replication capability of MxL to sub-100 nm and the use of contact aligners to achieve deep submicron feature sizes and to enable three-dimensional printing while providing an intermediate level of overlay accuracy.