Twin Polymerization--a New Principle for Hybrid Material Synthesis

Space-confined twin-polymerization enabling homogeneous integration of ultrafine TiO2 nanoparticles into a sulfur-doped carbon matrix for boosting lithium storage

Homogeneous integration of ultrafine TiO2 nanoparticles into a conductive sulfur-doped carbon skeleton was readily crafted by unusual space-confined twin-polymerization of a titanium-containing single-source coupled monomer and subsequent carbonization, producing a robust hetero-architecture for boosting lithium storage with large reversible capacity, high rate capability, and long-term cycling stability.

Porous carbon-carbon composite electrodes for vanadium redox flow batteries synthesized by twin polymerization

Highly porous carbon–carbon composite electrodes have been synthesized by surface twin polymerization on a macroporous polyacrylonitrile (PAN)-based substrate. For this purpose the compound 2,2′-spirobi[benzo-4H-1,3,2-dioxasiline] (Spiro), being a molecular precursor for phenolic resin and silica, was polymerized onto PAN-based felts with subsequent thermal transformation of the hybrid material-coated felt into silica-containing carbon. The following etching step led to high surface carbon–carbon composite materials, where each carbon component served a different function in the battery electrode: the carbon fiber substrate possesses a high electron conductivity, while the amorphous carbon coating provides the catalytic function. For characterization of the composite materials with respect to structure, porosity and pore size distribution scanning electron microscopy (SEM) as well as nitrogen sorption measurements (BET) were performed. The electrochemical performance of the carbon felts (CF) for application in all-vanadium redox flow batteries was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared to the pristine PAN-based felt the composite electrodes show significantly enhanced surface areas (up to 35 times higher), which increases the amount of vanadium ions that could be adsorbed onto the surface and thus contributes to an increased performance.

Synthesis, characterization and electrochemical evaluation of composite electrodes – synthesized via twin polymerization – for utilization in vanadium redox flow batteries.

Morphology on Reaction Mechanism Dependency for Twin Polymerization

An in-depth knowledge of the structure formation process and the resulting dependency of the morphology on the reaction mechanism is a key requirement in order to design application-oriented materials. For twin polymerization, the basic idea of the reaction process is established, and important structural properties of the final nanoporous hybrid materials are known. However, the effects of changing the reaction mechanism parameters on the final morphology is still an open issue. In this work, the dependence of the morphology on the reaction mechanism is investigated based on a previously introduced lattice-based Monte Carlo method, the reactive bond fluctuation model. We analyze the effects of the model parameters, such as movability, attraction, or reaction probabilities on structural properties, like the specific surface area, the radial distribution function, the local porosity distribution, or the total fraction of percolating elements. From these examinations, we can identify key factors to adapt structural properties to fulfill desired requirements for possible applications. Hereby, we point out which implications theses parameter changes have on the underlying chemical structure.

Spirocyclic tin salicyl alcoholates - a combined experimental and theoretical study on their structures, 119Sn NMR chemical shifts and reactivity in thermally induced twin polymerization

The spirocyclic tin salicyl alcoholate, 4H,4'H-2,2'-spirobi[benzo[d][1,3,2]dioxastannine] (1), and its 6,6'-dimethoxy (2) and 8,8'-di-tert-butyl-6,6'-dimethyl derivative (3) were synthesized and thermally induced twin polymerization of precursor 2 was performed to give a SnO2-containing hybrid material. Studies on the molecular structures of 1-3 were carried out using 119Sn{1H} CP MAS NMR spectroscopy and DFT calculations. Crystallization of compound 3 from dimethyl sulfoxide solution provided the Lewis acid-base adduct 3(dmso)2 exhibiting a hexacoordinated tin atom in the solid state, in agreement with the results of the spectroscopic and DFT calculation data. 119Sn NMR spectroscopy of the compounds 1-3 and 3(dmso)2 revealed equilibria among the diverse oligomers in solution phase pointing at hexacoordinated tin atoms.

Chiral molecular fluoridosilicates and their twin polymerization for the preparation of fluorine-doped mesoporous silica and microporous carbon

The synthesis of organic–inorganic hybrid materials, microporous carbon and fluorine-doped mesoporous silica by the twin polymerization of pentacoordinated fluoridosilicates is reported.

Design of nanostructured hybrid materials: twin polymerization of urethane-based twin prepolymers

Organic–inorganic hybrid materials with urethane functionalities were obtained by simultaneous twin polymerization of twin prepolymers in combination with the ideal twin monomer 2,2′-spirobi[4H-1,3,2-benzodioxasiline]. The twin prepolymers consist of a urethane-based prepolymer with reactive terminal groups which can react during the twin polymerization process. Nanostructured hybrid materials with integrated dialkylsiloxane crosslinked urethane structures, phenolic resin and SiO₂ are obtained in a one pot process. The effects of the polymerization temperature as well as those of various catalysts and reagent ratios on the polymerization behavior were investigated. The molecular structures of the obtained materials were determined by ¹³C- and ²⁹Si-{¹H}-CP-MAS NMR spectroscopies. HAADF-STEM-measurements were performed to prove the distribution of silicon in the hybrid material.

Organic–inorganic hybrid materials with urethane functionalities were obtained by simultaneous twin polymerization of twin prepolymers in combination with the twin monomer 2,2′-spirobi[4H-1,3,2-benzodioxasiline].

Hierarchically structured carbon and silica by chemical foaming

Foamed organic/silica hybrid materials are synthesized via cationic polymerization of organic carbonates with twin monomers. They are converted into hierarchically structured carbon and silica.

Electronic Structure Calculations and Experimental Studies on the Thermal Initiation of the Twin Polymerization Process

Presented here is a combined computational and experimental study on the thermal initiation process of the twin polymerization. Although thermally initiated twin polymerization offers a versatile scheme for obtaining hybrid organic/inorganic nanocomposite materials, the mechanism for its initiation is very different from the proton-initiated twin polymerization. In this study, the basic mechanism of the early steps of the polymerization process of 4 H,4 H'-2,2'-spirobi[benzo[d][1,3,2]dioxasiline] was investigated by using electronic structure calculations in conjunction with experimental differential scanning calorimetry studies. This way, the influences on the thermally initiated twin polymerization process could be analyzed in detail. The previous mechanistic hypotheses are systematically assessed herein to show that, based on the results, a new hypothesis for an initiation mechanism can be formulated that is in agreement with all experimental observations. These results suggest that, before the formation of the polymer networks, the thermal initiation starts with the formation of low-molecular-weight fragments that react to yield acidic groups. If a sufficient amount of these form, the reaction is ultimately funneled into a mechanism similar to that of proton-initiated twin polymerization.

Resin and carbon foam production by cationic step-growth polymerization of organic carbonates

Acid induced step-growth polymerizations of bis(p-methoxybenzyl) carbonate (pMBC), bis(m-methoxybenzyl) carbonate (mMBC) and difurfuryl carbonate (DFC) have been performed to produce resin-foams, because controlled release of carbon dioxide takes place during polymerization of those organic carbonates.

From molecular germanates to microporous Ge@C via twin polymerization

Four molecular germanates based on salicyl alcoholates, bis(dimethylammonium) tris[2-(oxidomethyl)phenolate(2-)]germanate (1), bis(dimethylammonium) tris[4-methyl-2-(oxidomethyl)phenolate(2-)]germanate (2), bis(dimethylammonium) tris[4-bromo-2-(oxidomethyl)phenolate(2-)]germanate (3) and dimethylammonium bis[2-tert-butyl-4-methyl-6-(oxidomethyl)phenolate(2-)][2-tert-butyl-4-methyl-6-(hydroxymethyl)phenolate(1-)]germanate (4), were synthesized and characterized including single crystal X-ray diffraction analysis. In the solid state, compounds 1 and 2 exhibit one-dimensional hydrogen bonded networks, whereas compound 4 forms separate ion pairs, which are connected by hydrogen bonds between the dimethylammonium and the germanate moieties. The potential of these compounds for thermally induced twin polymerization (TP) was studied. Germanate 1 was converted by TP to give a hybrid material (HM-1) composed of phenolic resin and germanium dioxide. Subsequent reduction with hydrogen provided a microporous composite containing crystalline germanium and carbon (Ge@C -C-1, germanium content ∼20%). Studies on C-1 as an anode material for Li-ion batteries revealed reversible capacities of ∼370 mA h gGe@C(-1) at a current density up to 1384 mA g(-1) without apparent fading for 500 cycles.

Ternary organic–inorganic nanostructured hybrid materials by simultaneous twin polymerization

The acid and base catalyzed simultaneous twin polymerization to produce ternary organic–inorganic nanostructured hybrid materials consisting of a cross-linked phenolic resin, silica and a disubstituted polysiloxane.

Multiple polymerization – formation of hybrid materials consisting of two or more polymers from one monomer

The synthesis of hybrid materials consisting of three different components from only one monomer is reported for the first time.

Nanocomposites by the use of simultaneous twin polymerization: tin alloys in a carbon/silica matrix

Twin polymerization is used as a novel nonaqueous route to synthesize composites composed of nanoparticular tin alloys in a porous carbon/silica matrix.

Polyamide 6/silica hybrid materials by a coupled polymerization reaction

Polyamide 6/SiO₂hybrid materials with an adjustable SiO₂amount were produced by the coupled polymerisation of three monomeric components namely 1,1′,1′′,1′′′-silanetetrayltetrakis-(azepan-2-one), 6-aminocaproic acid and ε-caprolactam within one process.