Difunctional Methacrylate Monomers Research Articles

Si/SiOC/Carbon Lithium‐Ion Battery Negative Electrode with Multiple Buffer Media Derived from Cross‐Linked Dimethacrylate and Poly (dimethyl siloxane)

AbstractSilicon holds a great promise for next generation lithium‐ion battery negative electrode. However, drastic volume expansion and huge mechanical stress lead to poor cyclic stability, which has been one of the major drawbacks to prevent its practical applications. In this work, difunctional methacrylate monomers and vinyl terminated poly (dimethyl siloxane) have been cross‐linked via a facile scalable thermal polymerization process, where SiOC (silicon oxycarbide) and carbon network are formed upon calcination. With the multiple buffer media of SiOC and carbon, the electrochemical properties of the Si/SiOC/C (silicon/silicon oxycarbide/carbon) nanohybrid have been effectively improved in terms of both cyclic and rate performance. After one hundred cycles the discharge capacities of Si/SiOC/C composite is also 443 mAhg−1 while the capacity retention is 83.4 %. Through charge and discharge in higher current density, the capacities can also recover to the similar level.

Corrigendum: Role of Nickel Nanoparticles in High-Performance TiO2 /Ni/Carbon Nanohybrid Lithium/Sodium-Ion Battery Anodes.

Super-small sized TiO2 nanoparticles are in situ co-composited with carbon and nickel nanoparticles in a facile scalable way, using difunctional methacrylate monomers as solvent and carbon source. Good control over crystallinity, morphology, and dispersion of the nanohybrid is achieved because of the thermosetting nature of the resin polymer. The effects of the nickel nanoparticle on the composition, crystallographic phase, structure, morphology, tap density, specific surface area, and electrochemical performance as both lithium-ion and sodium-ion battery anodes are systematically investigated. It is found that the incorporation of the in situ formed nickel nanoparticles with certain content effectively enhances the electrochemical performance including reversible capacities, cyclic stability and rate performance as both lithium-ion and sodium-ion battery anodes. The experimental I-V profiles at different temperatures and theoretical calculations reveal that the charge carriers are accumulated in the amorphous carbon regions, which act as scattering centers to the carriers and lower the carrier mobility for the composite. With increasing nickel content, the mobility of the charge carriers is significantly increased, while the number of the charge carriers maintains almost constant. The nickel nanoparticles provide extra pathways for the accumulated charge, leading to reduced scatterings among the charge carriers and enhanced charge-carrier transportation.

MnO/Metal/Carbon Nanohybrid Lithium‐Ion Battery Anode With Enhanced Electrochemical Performance: Universal Facile Scalable Synthesis and Fundamental Understanding

AbstractMnO holds a great promise as an alternative lithium‐ion battery anode. It is crucial to improve the cyclic stability and rate capability of MnO‐based anodes. A facile scalable strategy to incorporate metal nanoparticles into the MnO/carbon anodes is developed as demonstrated by the MnO/Ag/C and MnO/Ni/C nanohybrids. Difunctional methacrylate monomers are used as solvent and carbon source, where the precursors of MnO and metal are homogeneously mixed at the molecular level and converted into a thermosetting polymer. MnO and metal nanoparticles are in situ formed and homogeneously embedded in the in situ formed carbon matrix after the carbonization process. The influence of the metal nanoparticles on the structure and properties of the MnO‐based anodes is systematically investigated. The mass composition of the MnO phase within the nanohybrid is controlled to be at a relatively low level, which is helpful for maintaining a good cyclic stability at the expense of the reversible capacities. However, the reversible capacities are increased by the incorporation of the metal nanoparticles due to enhanced electrochemical kinetics, where both excellent cyclic stability and rate performance are exhibited simultaneously. The mechanism responsible for the performance improvement is explored by electrochemical impedance spectroscopy, cyclic voltammetry, and temperature‐dependent resistivity measurements.

Synergistic effects from super-small sized TiO2 and SiOx nanoparticles within TiO2/SiOx/carbon nanohybrid lithium-ion battery anode

Abstract TiO2/SiOx/carbon nanohybrid consisting of super-small sized TiO2 and SiOx nanoparticles is in situ formed within the in situ formed carbon matrix using difunctional methacrylate monomers as solvent and carbon source. The relative composition of TiO2 and SiOx is systematically tuned by varying the feeding mass ratio of the precursors (TEOS/TTIP) and HF etching treatment after the carbonization process. The super-small sized TiO2 and SiOx nanoparticles are well intermixed with each other and homogeneously dispersed throughout the carbon matrix, where a good control over crystallinity, morphology, and microstructure of the nanohybrids is achieved. Synergistic effects are demonstrated from both TiO2 and SiOx regarding the increased reversible capacity from the SiOx phase and maintenance of good cyclic stability by the TiO2 component when being used in lithium-ion batteries. A good balance is achieved in terms of reversible capacity, capacity retention, and rate performance in the TiO2/SiO2/C nanohybrid prepared with the TEOS/TTIP mass ratio of 1.0. The reversible capacities are improved by around two times compared to the SiOx free sample with a good capacity retention of 78 %, which exhibits good rate capability at the current densities up to 3350 mA g−1 as well.

Role of Nickel Nanoparticles in High-Performance TiO2 /Ni/Carbon Nanohybrid Lithium/Sodium-Ion Battery Anodes.

Super-small sized TiO2 nanoparticles are in situ co-composited with carbon and nickel nanoparticles in a facile scalable way, using difunctional methacrylate monomers as solvent and carbon source. Good control over crystallinity, morphology, and dispersion of the nanohybrid is achieved because of the thermosetting nature of the resin polymer. The effects of the nickel nanoparticle on the composition, crystallographic phase, structure, morphology, tap density, specific surface area, and electrochemical performance as both lithium-ion and sodium-ion battery anodes are systematically investigated. It is found that the incorporation of the in situ formed nickel nanoparticles with certain content effectively enhances the electrochemical performance including reversible capacities, cyclic stability and rate performance as both lithium-ion and sodium-ion battery anodes. The experimental I-V profiles at different temperatures and theoretical calculations reveal that the charge carriers are accumulated in the amorphous carbon regions, which act as scattering centers to the carriers and lower the carrier mobility for the composite. With increasing nickel content, the mobility of the charge carriers is significantly increased, while the number of the charge carriers maintains almost constant. The nickel nanoparticles provide extra pathways for the accumulated charge, leading to reduced scatterings among the charge carriers and enhanced charge-carrier transportation.

Silicon/carbon lithium-ion battery anode with 3D hierarchical macro-/mesoporous silicon network: Self-templating synthesis via magnesiothermic reduction of silica/carbon composite

Silicon (Si) is regarded as one of the most promising lithium-ion battery anodes to replace commercial graphite due to its exceptional theoretical capacity, appropriate voltage profile, environmental friendliness and natural abundance. It is crucial to develop effective strategies to improve the cyclic performance of the Si anodes. A new concept to synthesize Si/carbon composite with three dimensional (3D) hierarchical macro-/mesoporous structure is reported. Stöber silica (SiO2) particles are used as templating agent and precursor for Si simultaneously. Unlike conventional work reported previously, here the silica particles are composited with carbon matrix before magnesiothermic reduction. Difunctional methacrylate monomers are used as solvent and carbon source coupled with a fast, environmental friendly and energy saving photo polymerization to prepare the SiO2/C composite. Based on a self-templating mechanism during the magnesiothermic reduction process, 3D hierarchical macro-/mesoporous Si is formed in situ within the carbon matrix. Compared to the Si/carbon composite composed of micro-sized Si and bare macro-/mesoporous Si, the cyclic performance is significantly improved with a reasonable mass loading density. Good rate performance is exhibited comparable to the bare porous Si. The hierarchical macro-/mesoporous structure within the carbon matrix helps to retain the porous Si structure, which effectively improves the electrochemical performance.

Scalable Synthesis of Hierarchical Antimony/Carbon Micro-/Nanohybrid Lithium/Sodium-Ion Battery Anodes Based on Dimethacrylate Monomer

A facile scalable synthesis of hierarchical Sb/C micro-/nanohybrid has been addressed in this work, which possesses the advantages of both micrometer and nanometer scale structures as lithium-ion battery anode. Difunctional methacrylate monomers are used as solvent and carbon source as well. Liquid precursor of antimony(III) n-butoxide is dissolved in the resin monomer solution, and further incorporated into the cross-linking polymer network via photo polymerization. Through calcination in argon/hydrogen atmosphere, antimony nanoparticles are in situ formed by carbothermal reduction, and homogeneously embedded in the in situ formed micrometer sized carbon matrix. The morphology, structure, crystallinity, spatial dispersion, composition, and electrochemical performance of the Sb/C micro-/nanohybrid are systematically investigated. The cyclic and rate performance of the Sb/C micro-/nanohybrid anode have been effectively improved compared to the pure carbon anode. A reversible capacity of 362 mAh g−1 is achieved with a reasonable mass loading density after 300 cycles at 66 mA g−1, corresponding to capacity retention of 79%. With reducing mass loading density, the reversible capacity reaches 793 mAh g−1 after 100 cycles. Moreover, the electrochemical performance of Sb/C micro-/nanohybrid as sodium-ion battery anode is also investigated in this study. Sb/C hierarchical micro-/nanohybrid lithium-ion battery anode with good cyclic stability is synthesized in a scalable way using difunctional methacrylate monomers as solvent and carbon source, where a reversible capacity of 362 mAh g−1 is achieved after 300 cycles with a reasonable mass loading density, corresponding to capacity retention of 79%

Scalable in Situ Synthesis of Li4Ti5O12/Carbon Nanohybrid with Supersmall Li4Ti5O12 Nanoparticles Homogeneously Embedded in Carbon Matrix.

Li4Ti5O12 (LTO) is regarded as a promising lithium-ion battery anode due to its stable cyclic performance and reliable operation safety. The moderate rate performance originated from the poor intrinsic electron and lithium-ion conductivities of the LTO has significantly limited its wide applications. A facile scalable synthesis of hierarchical Li4Ti5O12/C nanohybrids with supersmall LTO nanoparticles (ca. 17 nm in diameter) homogeneously embedded in the continuous submicrometer-sized carbon matrix is developed. Difunctional methacrylate monomers are used as solvent and carbon source to generate TiO2/C nanohybrid, which is in situ converted to LTO/C via a solid-state reaction procedure. The structure, morphology, crystallinity, composition, tap density, and electrochemical performance of the LTO/C nanohybrid are systematically investigated. Comparing to the control sample of the commercial LTO composited with carbon, the reversible specific capacity after 1000 cycles at 175 mA g-1 and rate performance at high current densities (875, 1750, and 3500 mA g-1) of the Li4Ti5O12/C nanohybrid have been significantly improved. The enhanced electrochemical performance is due to the unique structure feature, where the supersmall LTO nanoparticles are homogeneously embedded in the continuous carbon matrix. Good tap density is also achieved with the LTO/C nanohybrid due to its hierarchical micro-/nanohybrid structure, which is even higher than that of the commercial LTO powder.

A UV curable resin with reworkable properties: application to imprint lithography

Difunctional methacrylate monomers having a hemiacetal ester moiety in the molecule were used to prepare a plastic replica of an original mold for imprint lithography. UV curing of the monomers was performed with 365 nm light and photo-induced degradation of the cured resins was performed using 254 nm light.

Fluorescence monitoring of photoinitiated polymerization reactions: Synthesis, photochemical study and behaviour as fluorescent probes of new derivatives of 4′-dimethylaminostyryldiazines

The fluorescence emission of three new fluorescent probes has been studied in environments of different polarity and viscosity. The diazine moieties behave as electron acceptor and a good correlation has been found between their reduction potentials and the dipole moments in the excited state (estimated from solvatochromic plots using Lippert equations). The probes have shown to be sensitive to changes in both microviscosity and micropolarity of the surroundings. They have been used as fluorescent sensors to monitor the photopolymerization reactions of some mono- and difunctional methacrylate monomers in bulk. The fluorescence emission band of the probes showed an increase in intensity, as well as an hypsochromic shift, as the degree of conversion increases, throughout the entire polymerization range in the different systems checked.

Photoinitiated Polymerization of Di- and Tetrafunctional Methacrylic Monomers in a SBS Matrix. Kinetic, Mechanistic, and Structural Aspects

The kinetics and mechanism of the photoinitiated polymerization of tetrafunctional and difunctional methacrylate monomers (di-, hexa-, and decamethylene dimethacrylates; and ethylhexyl and dodecyl methacrylates) in a styrene−butadiene−styrene (SBS) block copolymer matrix have been studied. Reaction diffusion was found to be the only termination mechanism for tetrafunctional monomers when the monomer concentration in the matrix is below 30−40%; for higher monomer concentrations, reaction diffusion controls the termination process only after approximately 10% conversion was reached. The values of both the propagation kinetic constant and the overall double bond conversion for the three tetrafunctional monomers studied showed the following order: deca- > hexa- > dimethylene dimethacrylate. The termination process in the photoinitiated polymerization of difunctional methacrylate monomers is clearly controlled by reaction diffusion right from the beginning of the polymerization reaction only at a very low mon...

Facile Synthesis and Polymerization of Ether Substituted Methacrylates

New difunctional methacrylate monomers containing β heteroatoms have been synthesized from α-hydroxymethylacrylate esters or α-chloromethylacryloyl chloride. These monomers are more reactive than their alkane counterparts (e.g., ethacrylates), giving polymers with molecular weights comparable to poly(itaconate)s. The simple synthetic approach described allows a wide range of difunctionalized acrylate monomers to be produced. Variations in both ester and ether substituents were explored for ease of synthesis and polymerization.

Low-temperature, free-radical post-polymerization of difunctional methacrylate monomers

The low-temperature post-polymerization of the difunctional monomers allyl methacrylate and diethylene glycol dimethacrylate, on heating up in the glassy state after γ-irradiation at —196°C, has been investigated. The electron paramagnetic resonance, low-temperature calorimetry and nuclear magnetic resonance methods were used. In polymerization of allyl methacrylate without additives, poly(ally methacrylate) in which all the allyl double bonds are preserved, was obtained up to a conversion of 20%. It was found that in low-temperature post-polymerization of allyl methacrylate, allyl methacrylate with ZnCl 2, and diethylene glycol dimethacrylate with butyl methacrylate, gelation begins at higher conversions than in polymerization of such systems under ordinary conditions.