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Gold nanoparticles smaller than 5 nm were encapsulated in the special space of the loop-cluster corona on a polymer vesicle. They exhibited high catalytic activity in the reduction of nitrophenols, but with remarkable oxygen-induced induction times.

Comb-like copolymers are usually structured by grafting polymeric side chains onto main polymer chain. There are few reports of comb-on-comb polymers in which dense secondary side chains are grafted onto primary side chain. In this work, we synthesized comb polymers with grafted-on-graft side chains (c-PEI-g-Acyl) via an effective acylation reaction of comb polymers possessing polyethyleneimine (PEI) side chain with long-alkyl acyl chlorides. For comparison, we also synthesized homopolymers l-PEI-g-Acyls via reaction of linear PEI with long-alkyl acyl chlorides. Then, we investigated their crystalline feature in the film formation by XRD, DSC and SEM, and found that the polymers tend to form hexagonal lamella structures with bilayer alkyl spacing. The comb polymers c-PEI-g-Acyls and linear polymers l-PEI-g-Acyls were used in preparation of honeycomb film by the "breath-figure" process by dropping chloroform solution of the polymers on substrate. Different to many honeycomb polymeric films which are supported by amorphous phase, interestingly, our polymers easily afford honeycomb films which are supported by crystalline lamellae frames under higher humidity condition. It was found that the comb polymers of c-PEI-g-Acyls with longer PEI primary side chain and long alkyl secondary side chain have advantages in producing honeycomb film than linear polymers of l-PEI-g-Acys.

In chirality research area, it is of interest to reveal the chiral feature of inorganic nanomaterials and their enantioselective interactions with biomolecules. Although common Raman spectroscopy is not regarded as a direct chirality analysis tool, it is in fact effective and sensitive to study the enantioselectivity phenomena, which is demonstrated by the enantio-discrimination of amino acid enantiomers using the polydopamine-modified intrinsically chiral SiO2 nanofibers in this work. The Raman scattering intensities of an enantiomer of cysteine are more than twice as high as those of the other enantiomer with opposite handedness. Similar results were also found in the cases of cystine, phenylalanine, and tryptophan enantiomers. In turn, these organic molecules could be used as chirality indicators for SiO2, which was clarified by the unique Raman spectra-derived mirror-image relationships. Thus, an indirect chirality detection method for inorganic nanomaterials was developed.

Two types of double-hydrophilic comb-coil block copolymers, (PVBC-g-PMOZ)-b-PNIPAM and (PVBC-g-PEI)-b-PNIPAM, possessing combs of poly(methyloxazoline) (PMOZ)/crystalline poly(ethyleneimine) (PEI) ...

It has been generally recognized that chiral inorganic materials can be efficiently fabricated via a templated-synthesis route in the presence of chiral organic components of molecules or aggregates. However, there are few examples regarding the reverse process, that is, chirality transfer from chiral inorganics to other organics. Herein, we developed an asymmetric synthesis of chiral phenolic resins (RF) by employing synthetic chiral silica bonded covalently with amine residues as an asymmetric medium to asymmetrically mediate the polymerization of resorcinol (R) with formaldehyde (F). The resultant composites, consisting of RF resins and SiO2, showed chiroptical signals with a mirror relationship that appeared remarkably in their circular dichroism (CD) spectra around the adsorption bands of the RF resins. Interestingly, the RF resins still retained CD activities even after the removal of the chiral silica using HF (aq.), suggesting efficient chirality transfer from the chiral silica to the phenolic resins. We proposed that the origin of the chirality in the RF resins is the appearance of axial asymmetry due to the formation of distorted calixarene-like cyclic structures, which is supported by the emergence of chirality from the reaction of C-tetramethylcalix[4]resorcinarene and formaldehyde catalyzed by chiral silica-bonded amine residues.

Shape-persistent macrocycles and 3D nanocages have been prepared in one-pot under MeCN-promoted dynamic covalent bond conditions starting from silane catecholates, whose structures were confirmed by X-ray crystallography. Cation-exchange reactions of macrocycles and nanocages were performed along with the encapsulation of ammonium ions within the cavity of an anionic macrocycle and a tetrahedral nanocage.

Acid–base complexes prepared from sub-5 μm polyethyleneimine (PEI) microballs and dicarboxylic acids such as adipic acid (AA), succinic acid (SA), meso-tartaric acid (m-TA) as well as mucic acid (MA) were used as catalytic templates in hydrolytic condensation of tetramethoxy silane (TMOS). By means of FT-IR, 13C NMR, 29Si NMR, XRD, SEM, TGA and nitrogen sorption isotherms, we thoroughly investigated the effects of the dicarboxylic acids complexed with PEI microballs on the resultant silica structures. We found that in this silica deposition process, the presence of the dicarboxylic acids of adipic acid (AA) and succinic acid (SA), which do not have alcoholic groups, could adapt to deposit high content of silica than the alcoholic acids of meso-tartaric acid (m-TA) and mucic acid (MA). More interestingly, the surface structures of the resultant silica microballs were different with different types of acids. The presence of m-TA and MA with meso-type alcoholic structures produced nanofibre or nanoplate-covered silica microballs, while the presence of AA and SA led to the formation of nanoparticles-covered silica microballs. Accompanying these structural features, the BET surface areas of the four types of acid-mediated silica microballs after calcination at 800 °C appeared remarkably different with the order of 615 > 430 > 133 > 96 m2 g−1, respectively, corresponding to the contribution of MA, m-TA, SA and AA. These results evidently indicate that the structures of the dicarboxylic acids associated with PEI microballs play a messenger-like role to tune the silica structures.

Polystyrenic microspheres in the sub 5 micrometer size range (micro-gel) with –CH2Cl active sites were synthesized via the dispersion polymerization of 4-chloromethylstyrene, divinyl benzene and methoxy polyethylene glycol acrylate. Then, theophylline residues were introduced onto the polystyrenic microspheres via the substitution of the chloride in the –CH2Cl group to prepare chelate type microspheres of μ-T2. It was found that the microspheres have co-continuous structures, monodispersed particle sizes, and excellent solvent and water wettability. Using the μ-T2 microspheres possessing theophylline residues, adsorption experiments involving the adsorption of palladium(II), copper(II) and platinum(IV) from acidic chloride media under both individual and mixed conditions were carried out and it was found that the μ-T2 microspheres exhibited excellent adsorption selectivity for palladium(II) over copper(II) and platinum(IV). It was also revealed that thiourea or ammonia solutions are the most effective in desorbing palladium ions from the microspheres. Despite being used in four adsorption–desorption cycles, the μ-T2 microspheres were still able to strongly adsorb palladium ions, with an adsorption of over 85%. In addition, the μ-T2 microspheres also showed palladium capturing ability even in very dilute palladium solutions (below 1.0 ppm). Interestingly, the μ-T2 microsphere-adsorbed palladium ions exhibited excellent catalytic activity in the Suzuki–Miyaura coupling reaction of bromobenzene and phenylboronic acid, yielding biphenyl in 100% under the conditions within 1 hour at 50 °C in water.

In this work, we synthesized free-standing disk-shaped gels (FGPEI) from the chemical cross-linking of linear polyethyleneimine (LPEI), and investigated their crystalline features in gel state and templating function in mineralizations of silica and titania. It was found that the FGPEIs with different cross-linkers and different cross-linking degrees showed remarkable crystalline properties in water containing state but became amorphous in the swollen state in methanol. This is reversible by alternating the medium of water and methanol. The crystalline domains in the FGPEI were estimated by XRD as in the ranges of 3.0~11 nm. Immersion of the disk-shaped FGPEIs in tetramethoxysilane (TMOS) solutions spontaneously resulted in the corresponding hybrids SiO2/FGPEIs keeping the same disk shape with silica content of 63%. Calcinating the hybrids could tune them into monolith silica with mesoporous structure consisting of nanoparticle (ca. 20 nm) agglomeration. On the other hand, immersion of the FGPEI in tetraisopropyloxy titanium solution offered hybrid of TiO2/FGPEI but only with ca. 14% content of TiO2. However, calcination of this hybrid at different temperatures could result in monolith titania possessing mesopore and/or macropore structures inside with agglomeration of anatase- and/or rutile-type nanoparticles.

Herein, sub-5 μm microballs, with unusual forest-like structures consisting of a polystyrene network and forest-like poly(2-methyl-2-oxazoline) (PMOZ) and/or linear polyethyleneimine (LPEI) side chains, were synthesized by combining two isolated processes. The first process is the dispersion radical polymerization of 4-chloromethylstyrene (CMS) and divinylbenzene (DVB) in the presence of a stabilizer, polyvinylpyrrolidone (PVP), using 2,2′-azobis(isobutyronitrile) (AIBN) as an initiator, which produces a poly(4-chloromethylstyrene) type microgel (μ-PStCl). The second process is the cationic ring-opening polymerization of 2-methyl-2-oxazoline (MOZ) using μ-PStCl as a solid initiator, which produces poly(2-methyl-2-oxazoline)-grafted microballs (μ-PSt-g-PMOZ). The latter, possessing PMOZ side chains, was transformed into poly(ethyleneimine)-grafted microballs (μ-PSt-g-PEI) via treatment with HCl (aq). Moreover, the three types of microballs μ-PStCl, μ-PSt-g-PMOZ, and μ-PSt-g-PEI of 1–3 micrometer in diameter were characterized by FT-IR, 13C CP/MAS NMR, elemental analysis, XRD, and SEM. Both the microballs μ-PSt-g-PMOZ and μ-PSt-g-PEI, which resembled the assemblies of hydrophilic comb polymers in their chemical structure, exhibited good wettability in an aqueous phase. In particular, the μ-PSt-g-PEI microballs, which have forest-like basic polyamine chains throughout the microballs, act as catalytic templates in the hydrolytic polycondensation of tetramethoxysilane (TMOS) at room temperature to produce polymer/silica hybrid microballs of μ-PSt-g-PEI@SiO2 with 2.5–3.5 μm diameter and 35–70 wt% silica content depending upon the mediation conditions. Calcination of the μ-PSt-g-PEI@SiO2 hybrid microballs at 700, 800, and 900 °C resulted in silica microballs possessing 2–4 nm mesopores with reduced diameter from 3.5 to 1.2 μm and reduced BET surface area from 582 to 189 m2 g−1. It was confirmed that the sub-5 μm microballs of μ-PSt-g-PEI were very effective catalytic templates for the construction of silica microballs of different sizes (1–4 μm), different surface areas, and different (large hollow or co-continuous) internal structures.

Biomimetic synthesis of shaped functional inorganic materials is still a hot issue. In this work, we investigated the influence of crystallization conditions on formation of crystalline aggregates from comb-like polyethyleneimine (cPEI). A range of well-controlled polymeric aggregates rich in basic amine groups were prepared through a crystallization-driven self-assembly of cPEI under varied conditions such as different crystallization media (including solvent type and composition) and temperature, as well as the presence of metal cations of different valence. Meanwhile, these crystalline aggregates were applied as catalytic templates to replicate silica with corresponding structures and shapes. The cPEI templates and the templated silica products were mainly subjected to scanning electron microscope (SEM) observation, Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) measurements. The results indicated that cPEI was a very effective template component for the construction of specially structured silica materials being due to the special crystallites growing behavior of cPEI.

Amphiphilic block copolymers have attracted a considerable amount of attention in the past two decades because of their ability to self-organize into various complex nanostructures. Most of these studies concentrated on linear amphiphilic block copolymers. In this work, we focused our attention on two type unique comb-like copolymers which grafting amphiphilic diblocked side chains onto main chain of polystyrenic backbone. One is Type-I in which a block of hydrophilic polymers is located inside near to the backbone while other block of hydrophobic poly (phenyl-2-oxazoline) [PPOZ] is in outside far away the backbone. The other one is Type-O in which the hydrophobic block of PPOZ is grafted (inside) onto the main chain backbone then the hydrophilic block is joined (outside) on the PPOZ. A series of five kinds of Type-I and five kinds of Type-O comb-like block copolymers with different components of the amphiphiles were prepared. We performed self-assembly of them in a DMF/water or methanol/water (v/v, 1/9) media. All of Type-O comb-like block copolymers formed micelle. In contrast, in the case of Type-I, interestingly, the comb-like block copolymers possessing hydrophilic blocks with crystalline feature formed loop-cluster covered vesicles, while the others having non-crystalline hydrophilic blocks formed flower-like micelle. We proposed the self-organizing mechanism of these two types comb-like block copolymers and provides new molecular design strategy for the site-selective fabrication of vesicle/micelle possessing special surface structures.

In this paper, we firstly synthesized comb polymers with crystallizable poly(ethyleneimine) (PEI) side chains via a combination of reversible addition–fragmentation chain-transfer (RAFT) polymerization, cationic ring-opening polymerization (CROP), and further hydrolysis. At first, poly(4-chloromethylstyrene) (PCMS) and poly(4-chloromethylstyrene)-block-polystyrene (PCMS-b-PSt) as macroinitiators were synthesized by employing cumyl dithiobenzoate-mediated RAFT polymerization. Then, comb polymers with poly(2-methyloxyzoline) (PMOZ) side chains were prepared using PCMS and PCMS-b-PSt as macroinitiators in the presence of an excess of potassium iodide in benzonitrile, and the PMOZ side chains on the comb polymers were subsequently hydrolyzed into PEI. Furthermore, we demonstrated that the crystalline aggregates of these PEI-bearing comb polymers (i.e., comb-like PEI and comb-like PEI block with a PSt block) formed via crystallization-driven self-assembly in different aqueous media such as water, water/methanol, water/acetone and water/DMF could act as catalytic templates in silicification to give silica with well-controlled morphologies.

A general approach to fabricate a series of silica nanoobjects with sheet-like, tubular and hollow spherical shapes was reported. These silica nanoobjects were prepared by using water-dispersed diblock copolymer nanoobjects with glassy polystyrene cores and densely grafted poly(2-(dimethylamino)ethylmethacrylate) (PDMAEMA) shells as templates as well as catalysts. A sol–gel reaction of tetramethoxysilane (TMOS) was subsequently induced by PDMAEMA shells of shaped nanoobjects in water dispersions at near-neutral pH and under ambient conditions, and thus the shaped polymer@silica hybrids with a high silica content (around 70 wt% silica in hybrids) were obtained. Then silica nanoobjects of three different dimensions were further prepared by calcination at 650 °C to remove the organic components. The spherical and cylindrical silicas have a hollow structure. Formation of diblock copolymers, polymer nanoobjects, polymer@silica hybrids, and silica nanoobjects was characterized by 1H NMR spectroscopy, size exclusion chromatography (SEC), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), solid state 29Si CPMAS NMR analysis, N2 adsorption–desorption measurements, and Fourier-transform infrared spectroscopy (FT-IR). This methodology could be a general approach to fabricate various inorganic nanoparticles with different geometric shapes.

Organic molecules with accompanying self-organization have been a great subject in chemistry, material science and nanotechnology in the past two decades. One of the most important roles of organized organic molecules is the capability of templating complexly structured inorganic materials. The focus of this Minireview is on nanostructured silica with divergent morphologies and/or integrated chirality directed by organic templates of self-assembled polyamine/polypeptides/block copolymers, chiral organogels, self-organized chiral amphiphiles and chiral crystalline complexes, etc., by biomimetic silicification and conventional sol-gel reaction. Among them, biosilica (diatoms and sponges)-inspired biomimetic silicifications are particularly highlighted.

Environmentally friendly iron(II) catalysts for atom-transfer radical polymerization (ATRP) were synthesized by careful selection of the nitrogen substituents of N,N,N-trialkylated-1,4,9-triazacyclononane (R3 TACN) ligands. Two types of structures were confirmed by crystallography: "[(R3 TACN)FeX2 ]" complexes with relatively small R groups have ionic and dinuclear structures including a [(R3 TACN)Fe(μ-X)3 Fe(R3 TACN)](+) moiety, whereas those with more bulky R groups are neutral and mononuclear. The twelve [(R3 TACN)FeX2 ]n complexes that were synthesized were subjected to bulk ATRP of styrene, methyl methacrylate (MMA), and butyl acrylate (BA). Among the iron complexes examined, [{(cyclopentyl)3 TACN}FeBr2 ] (4 b) was the best catalyst for the well-controlled ATRP of all three monomers. This species allowed easy catalyst separation and recycling, a lowering of the catalyst concentration needed for the reaction, and the absence of additional reducing reagents. The lowest catalyst loading was accomplished in the ATRP of MMA with 4 b (59 ppm of Fe based on the charged monomer). Catalyst recycling in ATRP with low catalyst loadings was also successful. The ATRP of styrene with 4 b (117 ppm Fe atom) was followed by precipitation from methanol to give polystyrene that contained residual iron below the calculated detection limit (0.28 ppm). Mechanisms that involve equilibria between the multinuclear and mononuclear species were also examined.

Nanostructured silicon (Si) is a promising candidate for use in lithium ion batteries. In this work, one-dimensional SiO2 was obtained using linear polyethyleneimine (LPEI) as a biomimetic template/scaffold/catalyst, which was subsequently employed to fabricate nanostructured Si with a size of less than 10 nm in a SiO2 matrix using a solid–solid magnesiothermic reaction at a relatively low temperature of 500 °C. This procedure proved to be cost-effective and high-yielding and generated a product that could withstand a significant Si volume change during lithium insertion/extraction by combining the advantages of Si nanostructures with the buffer effect of the SiO2 matrix. In this manner, excellent cycling stability and a discharge capacity of more than 900 mAh/g were observed after 50 cycles. This work expands the structure-derived applications of bioinspired/biomimetic silica.

Poly(N-cyanoethylethyleneimine) (PCEI) obtained by Michael addition of linear poly(ethyleneimine) (LPEI) with acrylonitrile provided novel nanocrystalline entities which could serve as catalytic templates affording nanosheet-based structured silica under mild conditions.

Crystalline linear polyethyleneimine (LPEI) is a fascinating polymer that can be used as a catalyst, template and scaffold in order to direct the formation of silica with controllable compositions and spatial structures under mild conditions. Considering the crystallization and assembly of LPEI is temperature-dependent, we adopted different accelerated cooling processes of a hot aqueous solution of LPEI in order to modulate the LPEI crystalline aggregates. We then used them in the hydrolytic condensation of alkoxysilane. A series of silica with nanofibrils, nanotubes and nanowire-based structures were achieved simply by the LPEI aggregates which were pre-formed in defined cooling processes. These specific one-dimensional nanoscale structures assembled into microscale fibers-, sheet- and platelet-like coalescences. Furthermore, the deposition kinetics was also researched by the combination of other characterizations (e.g., pH measurement, 29Si MAS NMR). As a preliminary application, the hybrids of LPEI@SiO2 were used not only as an agent for reducing PtCl42− into Pt but also as host for loading Pt nanoparticles. The Pt-loaded silica showed good catalytic properties in the reduction of Rhodamine B by dimethylaminoborane (DMAB).

Constructing ceramic thin film on solid surfaces through biomimetic processing was demonstrated early in last decade by aqueous-phase precipitation of ceramics to a functionalized surface via crystal nucleation and growth, and finally forming a ceramic thin-film pathway. This technique was widely utilized in the surface modification and pattern formation of inorganic components on polymeric substrates because the straightforward process of functionalizing the surface by physical and chemical etching routes can yield a modified surface of intimation environment of inorganic deposition. However, this approach is often limited to crystallizable inorganic materials, and is not in favor of controlling the hierarchical structures of the inorganic thin film via programmable routes. It should be say that much can be learned from biosilica for the construction of biomimetic ceramic thin film. Diatoms and sponges have extremely exquisite structures that consist of silica and a small quantity of organic matrix. Research into diatoms and marine sponges has shed light into silica formation by biomimetic pathways. For example, the organic matrix isolated from different species of biosilica revealed that the biosilica formation is controlled by species-specific gene products, such as long-chain polyamines, polypeptides, and proteins. Although the detailed role of the organic matrix and the mechanism of formation of biosilica are unclear, the derivatives from poly(propyleneimine) (PPI, [NHCH2CH2CH2]) presented in the differently shaped biosilica patterns may potentially play key roles in constructing specific silica structures. Similar to the derivatives of PPI in nature, synthetic linear poly(ethyleneimine) (LPEI), possessing only secondary amine units (NHCH2CH2) in its backbone, is a candidate for silica-deposition matrix. Usually, LPEI forms different crystalline structures when associated with water in certain molar ratios (NHCH2CH2)/nH2O (n1⁄4 0.5, 1.0, 1.5, 2.0). We have found that when the crystalline aggregate self-organized from cooling a hot aqueous solution of LPEI is used as a matrix for inducing silica formation, it simultaneously plays three key roles: as a scaffold in directing silica deposition, as a template in controlling silica morphology, and as a catalyst in inducing the reaction in aqueous media. Complex-structured microsized silica composed of nanoelementary units has been developed by designing the primary structure of LPEI by association with organic acids, by complexation with metal cations, and so on. Recent progress of biosilica-inspired control for nanostructured silica (SiO2) and titania (TiO2) materials, which are mediated by polyamines, polypeptides, and natural proteins, showed promising prospect in directing the desired ceramic structures, and afforded great achievements in designing hierarchically structured silica powders. However, only a few reports have been published on the construction of silica or titania-based nanostructured surfaces on substrates via the biosilica-inspired route. To the best of our knowledge, there is no report describing the formation of highly refined nanotextured silica/titania films on arbitrary substrates with arbitrary shapes via a simple but highly efficient process. A LPEI-mediated silica-deposition pathway, which seems logically programmable, is capable of expanding towards the silica/titania film architecture on any solids surface. In this report, we present our two-step strategy (Fig. 1) for constructing silica/titania thin films on arbitrarily shaped substrates covered by a layer of LPEI. Unlike previous approaches, which rely on functionalized surfaces and aqueousmedia-reaction deposition, we start with first preparing the LPEI-covered layer on arbitrarily shaped substrates (such as flat, curved, tubular glass, plastic, metal, etc.) via wetting the substrates with a hot aqueous solution of LPEI. Following, a silica or titania film is formed by placing the LPEI-covered material into the inorganic-source solutions (for details, see Supporting Information). This pathway produces refined nanotextured SiO2 and TiO2 films with complex morphologies on the substrates. First, via a two-step strategy, we fabricated silica films on the inner wall of soda-lime glass tubes (6 O 100mm) using LP505 [(NHCH2CH2)505] and silica sources such as tetramethoxysilane (TMOS), MS51 (5-mer of tetramethoxysilane), and water glass (sodium silicate). Experimental details are described in the Supporting Information. As shown in Figure 2a, the glass tubes with thin silica films on their inner walls became opaque. When small glass pieces collected from breaking the tubes were subjected to scanning electron microscopy (SEM) examination, we noticed that, surprisingly, the inner surface is covered by vertically arranged silica nanoblades forming grass-like structures (nanograss, see Figs. 2b–f and S1, Supporting Information). This nanograss structure is obtained from all the silica sources

Silica deposition by mediation of aggregated linear poly(ethyleneimine) (LPEI) from a basic aqueous solution of sodium silicate can produce ordered silica with fibrous bundle structure hybridized with LPEIvia zero-emission of organic by-products. By changing the polymer concentration and pH value of the aqueous solution of sodium silicate, we were able to control the architecture of the resulting silica. This process is environmentally benign and inexpensive and thus would be feasible for industrial scale-up for the fabrication of silica nanomaterials. In addition, a typical fibrous silica bundle was characterized by fluorescence X-ray analysis, solid state 29Si (CP/MAS) NMR, TG/DTA, thermo-calcination, N2/He adsorption–desorption experiments, and high resolution TEM. Interestingly, the fibrous silica bundle, which contains about 25% LPEI, served as an effective nanoreactor to reduce metal ions into nearly cluster-size metallic nanoparticles inside the silica.

A unique hierarchically structured silica directed by simple hydrolytic condensation of tetramethoxysilane (TMOS) on aggregates of linear poly(ethylenemine) (LPEI) incorporated with acidic and basic additives was described. Interestingly, the shapes of the resulting silicas showed nanofiber-based plate, bundle, sphere, flower and stick upon the additives, such as HCl, ammonia, Tetra(4-sulfophenyl)porphyrin (TSPP), bifunctional organic acids. All the additives are relations in the proton transfer with LPEI in aqueous media thus induce the corresponding aggregates of the LPEI. Silicification just occurs on the aggregates to give the structured silica.

Fabrication of monodisperse silica spheres with bright emission features is still valuable in challenging since the spheres are widely applicable in the fields of catalysis, imaging material, bio-encapsulation, drug delivery, coatings, cosmetic, energy storage, and so on. In this paper, we demonstrated a new one-pot approach to uniformed silica spheres via mediation of linear poly(ethyleneimine)s (PEIs) and acidic dyes. PEIs with different architectures possessing only secondary amine in backbone were used as mediators for silica deposition from hydrolytic condensation of tetramethoxysilane (TMOS). Under the optimized medium composition of methanol/water with 70/30 in volume, the PEIs facilely promoted the hydrolytic condensation of TMOS to give rapidly and exclusively uniformed silica spheres. In this process, acidic dyes such as tetrakis(4-sulfonylphenyl)porphyrin (TSPP), tetrakis(4-carboxylphenyl)porphyrin (TCPP) can be incorporated with basic PEIs and play important role to produce relatively larger uniformed silica spheres entrapping the dyes inside. The diameters of the uniformed silica spheres ranged from 50 to 700 nm depending upon polymer architectures. From time-course investigation, it is confirmed that the formation of the silica spheres has three stages: 1) early formation of widely distributed smaller spheres; 2) growth to uniformed intermediate silica spheres and 3) further growth into larger spheres with narrow distribution.

In this paper, we describe the multiple morphogenesis of poly(ethyleneimine) (PEI)-directed silicas through the facile tuning of the media in which the PEIs pre-organize. The silica shapes and structures ranged from nanofiber-based asters, fans, particles, plates, and/or curved films to large aggregates composed of unit nanoribbon structures and networks that contained nanospheres or particles, depending on the media compositions or media modulations coupled with the polymer concentrations and chain architectures. We found that the media modulations not only controlled the formation of the silica unit structures but also manipulated the hierarchical structures based on the unit silicas. Furthermore, methanol modulation successfully allows us to elucidate the dependence of silica deposition ability on the polymer chain architectures that cause subtle differences in their aggregates. The approach of methanol modulation to obtain shaped silicas, which involves both PEI aggregation and silica deposition at room temperature, is of particular interest to applications for the immobilization of bioactive components.

Polymeric vesicular aggregates with spherical and tubular shapes were formed from the self-assembly of a porphyrin-centered amphiphilic star poly(oxazoline) [poly(phenyloxazoline)-block-poly(methyloxazoline)] in an DMF/water mixture containing excess DMF. The aggregates were evaluted by means of UV-Vis, fluorescent, 1 H NMR spectroscopies, and optical microscopy. The driving force to induce the vesicular aggregates is the interactions between poly(phenyloxazoline) segments wich were insoluble in DMF rich aqueous medium.

Recently, circularly polarized luminescence (CPL)-active systems have become a very hot and interesting subject in chirality- and optics-related areas. The CPL-active systems are usually available by two approaches: covalently combining a luminescent centre to chiral motif or associating the guest of luminescent probe to a chiral host. However, all the chiral components in CPL materials were organic, although the luminescent components were alternatively organics or inorganics. Herein, the first totally inorganic CPL-active system by "luminescent guest-chiral host" strategy is proposed. Luminescent sub-10 nm lanthanide oxides (Eu2 O3 or Tb2 O3 ) nanoparticles (guests) were encapsulated into chiral non-helical SiO2 nanofibres (host) through calcination of chiral SiO2 hybrid nanofibres, trapping Eu3+ (or Tb3+ ). These lanthanide oxides display circular dichroism (CD) optical activity in the ultraviolet wavelength and CPL signals around at 615 nm for Eu3+ and 545 nm for Tb3+ . This work has implications for inorganic-based CPL-active systems by incorporation of various luminescent guests within chiral inorganic hosts.

We report our new achievement on the direct generation of linear polyethylenimine@silica hybrid and silica thin films on various substrates, which is composed of 10 nm nanowire silica structure with tunable micro/nano hierarchical surface morphology. We found that a process for the rapid and controlled self-assembly of crystalline template layer of linear polyethylenimine on substrate surface is critical for the formation of ultrathin silica nanowire structure and micro/nano hierarchical morphology, since the template linear polyethylenimine layer directly promotes the hydrolytic condensation of alkoxysilanes. Templated silica mineralization on the self-assembled linear polyethylenimine layer was confirmed by the studies of X-ray photoelectron spectroscopy (XPS) and thin film X-ray diffraction (XRD). The surface of silica nanostructure and hierarchy could be well controlled by simply adjusting the conditions for LPEI assembly, such as the polymer concentrations and substrate surface property. After a simple fluorocarbon modification, the hierarchical silica nanowire thin film demonstrated robust and reliable super-repelling property toward a series of aqueous liquids (such as commercial inkjet (IJ) ink, soy source, milk). Comparative studies clearly confirmed the critical importance of surface hierarchy for enhancing super-repelling property. Moreover, we found that the forcibly formed dirty sports (both wet and dry) from the complexly composed liquids on the super-antiwetting surface could be easily and completely cleaned by simple water drop flow. We expect these tailored nanosurfaces would have the potentials for practical technological applications, such as liquid transferring, self-cleaning, microfluid, and biomedical-related devices.

The formation of silica films on the glass plate whose surface was precoated by crystalline linear poly(ethylenimine) (LPEI) in advance was systematically investigated via controlling the surface-specific crystallization of the LPEI on the glass plate. Immersing glass substrates into a hot aqueous solution of LPEI containing additives such as transition metal ions and acidic compounds and retaining them on 30 °C for desired periods resulted in the formation of crystalline LPEI layers on the substrates. Subsequently dipping this LPEI-coated glass into silica source solutions afforded successfully hierarchically structured silica film which coated continuously the surface of the substrates. In this two-step process, we found that the formation of hierarchically structured silica films strongly depended on the LPEI layer formed from the LPEI aqueous solutions containing different additives. The LPEI layer formed by changing the kinds of additives and their concentrations provides the differently structured silica films composed of turbine-like structures flatly lying-on and/or vertically standing-on as well as ribbon network structures on the surface of the substrates. Moreover, we functionalized these silica films by the introduction of hydrophobic alkyl chains or emissive Eu(III) complexes and investigated their wettability and emission properties.

porphyrin moieties located in the micellar core and/or in the micellar corona could not stack with each other. This is important in constructing porphyrin-isolated functional polymeric micelles. In order to find out more unique properties of polymeric micelles, we turned our attention to ionic star-shaped block copolymers possessing a porphyrin core. Compared to many micelles made from nonionic block copolymers, micelles formed from ionic block copolymers may have more interesting properties [3] because the ionic (cationic or anionic) segments are able not only to form corona in water but also to form a core in organic solvents. [4] Thus the corona acts as a polyelectrolyte and the core acts as an ionomer. Herein, I report the synthesis and micellar behavior of a novel porphyrin-centered cationic star block copolymer composed of cationic poly(ethyleneimine) (PEI) and hydrophobic poly(phenyloxazoline).

This is a report on the controlled generation of a polyamine@silica hybrid nanograss surface on arbitrary substrates. A very simple biomimetic silica mineralization reaction (i.e., ambient temperature and neutral aqueous medium conditioned hydrolytic polycondensation of alkoxy silane) performed on a self-assembled, nanostructured linear polyethyleneimine (LPEI) matrix allowed the production of nanostructured silica films with specific surface morphologies. It was found that the well-defined and densely arrayed nanograss surface of hybrid LPEI@silica could be achieved by adjusting the crystallization time of LPEI on the substrates, silica deposition time and LPEI concentrations. Comparative studies indicated that the LPEI with a linear backbone is important for nanograss formation due to its specific crystalline nature. By using a polystyrene substrate with tunable surface chemistry, we have confirmed that an efficient molecular-level interaction of LPEI with substrates is important for creation of a high-quality and continuous silica nanograss film. The combined studies from XRD, XPS and ζ potential supported that the crystalline, self-assembled and nanostructured LPEI layer on the substrate serves as catalyst-active and biomimetic template for site-selective silica mineralization to give the polyamine@silica nanograss. Moreover, by modifying the nanograss surface with a fluorocarbon compound, we are able to create a super-liquid-repellent surface, which shows the contact angle of >179°, 149.6° and 147.3° for water, 1 : 1 water–ethanol in volume (γ = 24.7 mN M−1) and inkjet ink (γ = 24.0 mN M−1), respectively. Our nanograss surface has potential applications for liquid transferring, self-cleaning, microfluid devices, sensing and cell engineering.

We report that a simple fabrication of a superhydrophobic nanosurface consisted of a grass-like silica thin film on the inner wall of a glass tube and its feature in water motion and water movement. The glass tube with a superhydrophobic inner wall can make the water flow with friction-drag reduction and completely preventing water sticking. Transferring water by this tube did not cause weight loss at all. Therefore, aqueous solutions containing high content metal ions were cross-moved without washing the tube used and no cross-contamination occurred after cross-movement. Furthermore, in an inside diameter of 6.0 mm glass tube where the half-length of the inner surface is covered by superhydrophobic nanograss and the other half is an unmodified hydrophilic surface, the water droplets flowing down from the hydrophilic side can be stopped spontaneously at the hydrophilic-superhydrophobic boundary as if there is an invisible flow-stopping fence built inside the glass tube.

The formation of hierarchical aggregates from linear polyethyleneimine (LPEI) was performed in aqueous media containing a series of divalent metal ions (MnII, FeII, CoII, NiII, CuII, ZnII) and their organization processes are investigated by transcribing the structure into hard silica frames which can be appropriately characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) measurements. Coexisting metal salts interact with LPEIvia coordination bonds between metal ions and amine groups in ethyleneimine (EI) units to form water-soluble complexes. Without suitable complexation, LPEI crystallizes without restriction and forms non-well controlled hierarchical microstructures even in the presence of metal ions. The molar ratios of EI units and metal ions strongly affect the morphologies of crystalline precipitates. Low values of the ratios lead to intricate flower-like structures composed of leaf-like fibers assembled in a random fashion. On the other hand, an increase of the ratios makes the structures well-shaped and flattened for constructing 2-D turbine-like morphology. These structures consist of numerous sheet structures grown in a radial fashion. XRD and XRF measurements reveal that these resulting solids are mainly composed of hydrated LPEI and imply that coordinating metal ions are located in the peripherals of LPEI microstructures. Finally, temporal morphological evolution experiments indicate that a metal ion which can coordinate with EI units serves as a regulator in the crystallization of LPEI and abundant crystal growth can proceed.