Uniform Lithium Deposition Induced by Polyacrylonitrile Submicron Fiber Array for Stable Lithium Metal Anode

The lithium dendrite growth and low Coulombic efficiency (CE) during lithium plating/striping cycles are the main obstacles for practical applications of lithium metal anode. Herein, we demonstrate that polyacrylonitrile (PAN) submicron fiber array could guide the lithium ions to uniformly disperse and deposit onto current collector. The PAN submicron fiber array nearly does not increase the volume of electrode with ultralow mass. By this simple design, we achieved stable cycling of lithium metal anode with an average CE of ∼97.4% for 250 cycles at a current density of 1 mA cm^-2 with total Li capacity of 1 mAh cm^-2.

Dynamic Self-Stiffening and Structural Evolutions of Polyacrylonitrile/Carbon Nanotube Nanocomposites

The self-stiffening under external dynamic strain has been observed for some artificial materials, especially for nanocomposites. However, few systematic studies have been carried out on their structural evolutions, and the effect of the types of nanofillers was unclear. In this study, we used a semicrystalline polymer, polyacrylonitrile (PAN), and various types of carbon nanomaterials including C₆₀, carbon nanotube (CNT), and graphene oxide (GO). An external uniaxial dynamic strain at small amplitude of 0.2% was applied on the prepared nanocomposite films. It was observed that PAN/CNT exhibited significant self-stiffening behavior, whereas PAN/GO showed no response. Systematic characterizations were performed to determine the structural evolutions of PAN/CNT film during dynamic strain testing, and it was found that the external dynamic strain not only induced the crystallization of PAN chains but also aligned CNT along the strain direction.

Electrospun Nanofibers Made of Silver Nanoparticles, Cellulose Nanocrystals, and Polyacrylonitrile as Substrates for Surface-Enhanced Raman Scattering

Nanofibers with excellent activities in surface-enhanced Raman scattering (SERS) were developed through electrospinning precursor suspensions consisting of polyacrylonitrile (PAN), silver nanoparticles (AgNPs), silicon nanoparticles (SiNPs), and cellulose nanocrystals (CNCs). Rheology of the precursor suspensions, and morphology, thermal properties, chemical structures, and SERS sensitivity of the nanofibers were investigated. The electrospun nanofibers showed uniform diameters with a smooth surface. Hydrofluoric (HF) acid treatment of the PAN/CNC/Ag composite nanofibers (defined as p-PAN/CNC/Ag) led to rougher fiber surfaces with certain pores and increased mean fiber diameters. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed the existence of AgNPs that were formed during heat and HF acid treatment processes. In addition, thermal stability of the electrospun nanofibers increased due to the incorporation of CNCs and AgNPs. The p-PAN/CNC/Ag nanofibers were used as a SERS substrate to detect p-aminothiophenol (p-ATP) probe molecule. The results show that this substrate exhibited high sensitivity for the p-ATP probe detection.

Dye-Affinity Nanofibrous Membrane for Adsorption of Lysozyme: Preparation and Performance Evaluation

Polyacrylonitrile (PAN) nanofibrous membrane was prepared by an electrospinning technique. After heat treatment and alkaline hydrolysis, the weak ion exchange membrane was grafted with chitosan molecule and then covalently immobilized with a Cibacron Blue F3GA (CB). Fibre diameter, porosity and pore size of the membrane and immobilized dye density were characterized. Furthermore, the membrane was applied to evaluate the binding performance of lysozyme under various operating parameters (pH, chitosan mass per volume ratio, dye concentration, ionic strength and temperature) in batch mode. The experimental results were directly applied to purify lysozyme from chicken egg white by membrane chromatography. The results showed that the capture efficiency, recovery yield and purification factor were 90 and 87%, and 47-fold, respectively, in a single step. The binding capacity remained consistent after five repeated cycles of adsorption-desorption operations. This work demonstrates that the dye-affinity nanofibrous membrane holds great potential for purification of lysozyme from real feedstock.

Carbonization with Misfusion: Fundamental Limits of Carbon-Fiber Strength Revisited

D-loops, a new type of structural defect in carbon fibers, are presented, which have highly detrimental effect on their mechanical properties and can define a new fundamental upper limit to their strength. These defects form exclusively during polyacrylonitrile carbonization, act as stress concentrators in the graphitic basal plane, and cannot be removed by local annealing.

Clustering-Triggered Emission of Nonconjugated Polyacrylonitrile

Intrinsic emission from nonconjugated polymers has attracted considerable attention owing to its fundamental importance and intensive applications in diverse fields. The emission mechanism, however, is still in debate. Herein, nonconjugated polyacrylonitrile (PAN) molecules are found to be virtually nonluminescent in dilute solutions, while being highly emissive when concentrated or aggregated as nanosuspensions, solid powders, and films, exhibiting distinct aggregation-induced emission (AIE) characteristics. Moreover, triplet emissions of delayed fluorescence and room temperature phosphorescence are detected from the solid powders. Such unique emission of nonconjugated PAN is ascribed to the formation of cyano clusters, which act as the exact chromophores. In these clusters, through space electronic interactions, namely overlap of π and lone pair (n) electrons among cyano groups extend the conjugation and meanwhile rigidify the molecular conformations, thus offering remarkable emission upon irradiation. The AIE phenomenon can also be well rationalized by the formation of cyano clusters together with conformation rigidification. And the triplet emissions shall be originated from the n-π* transition owing to the presence of lone pairs. It is believed that such clustering-triggered emission mechanism is instructive for further development of unorthodox luminogens.

Laser Carbonization of PAN-Nanofiber Mats with Enhanced Surface Area and Porosity

Here we present a novel laser process to generate carbon nanofiber nonwovens from polyacrylonitrile. We produce carbon nanofabrics via electrospinning followed by infrared laser-induced carbonization, facilitating high surface area and well-controlled hierarchical porosity. The process allows precise control of the carbonization conditions and provides high nanoscale porosity. In comparison with classical thermal carbonization, the laser process produces much higher surface areas and smaller pores. Furthermore, we investigate the carbonization performance and the morphology of polyacrylonitrile nanofibers compounded with graphene nanoplatelet fillers.

Tailoring Water-Resistant and Breathable Performance of Polyacrylonitrile Nanofibrous Membranes Modified by Polydimethylsiloxane

The demand of water-resistant and breathable materials applied to a separation medium and protective garments is steadily increasing. Typical approaches to obtain these functional materials are based on hydrophobic agents and porous substrates with small fiber diameter, tiny pore, and high porosity. However, a fluorinated hydrophobic finishing agent usually employed in providing effective waterproofness is limited with respect to their environmental persistence and toxic potential. Herein, with the aim to keep a balance between the water-resistance and breathability as well as mechanical properties, we fabricate a novel fluoride-free functional membrane by electrospun polyacrylonitrile (PAN) nanofibers modified with polydimethylsiloxane (PDMS). As determined by morphological, DSC, and FT-IR analyses, the curing reaction of PDMS macromolecules formed an abundance of hydrophobic adhesive structures, which improved the waterproof performance dramatically and imparted relative good breathability at the same time. By systematically tuning the curing temperature as well as the concentration of PDMS, the modified PAN membranes with 4 wt % PDMS possessed good water-resistance (80.9 kPa), modest vapor permeability (12.5 kg m^-2 d^-1), and air permeability (9.9 mm s^-1). Compared with pristine PAN membranes, the modified membranes were endowed with enhanced tensile stress of 15.7 MPa. The good comprehensive performance of the as-prepared membranes suggested their potential applications in protective clothing, membrane distillation, self-cleaning materials, and other medical products. Furthermore, the proposed relationship between porous structure and waterproof/breathable property as one considerable principle is applicable to designing functional membranes with different levels of protective and comfortable performance.

Manufacturing and investigation of physical properties of polyacrylonitrile nanofibre composites with SiO2, TiO2 and Bi2O3 nanoparticles

The aim of this study was to produce nanocomposite polymer fibres, consisting of a matrix of polyacrylonitrile (PAN) and a reinforcing phase in the form of SiO2/TiO2/Bi2O3 nanoparticles, by electrospinning the solution. The effect of the nanoparticles and the electrospinning process parameters on the morphology and physical properties of the obtained composite nanofibres was then examined. The morphology of the fibres and the dispersion of nanoparticles in their volume were examined using scanning electron microscopy (SEM). All of the physical properties, which included the band gap width, dielectric constant and refractive index, were tested and plotted against the concentration by weight of the used reinforcing phase, which was as follows: 0%, 4%, 8% and 12% for each type of nanoparticles. The width of the band gap was determined on the basis of the absorption spectra of radiation (UV-vis) and ellipsometry methods. Spectroscopic ellipsometry has been used in order to determine the dielectric constant, refractive index and the thickness of the obtained fibrous mats.

Photosensitizer-Embedded Polyacrylonitrile Nanofibers as Antimicrobial Non-Woven Textile

Toward the objective of developing platform technologies for anti-infective materials based upon photodynamic inactivation, we employed electrospinning to prepare a non-woven textile comprised of polyacrylonitrile nanofibers embedded with a porphyrin-based cationic photosensitizer; termed PAN-Por(+). Photosensitizer loading was determined to be 34.8 nmol/mg material; with thermostability to 300 °C. Antibacterial efficacy was evaluated against four bacteria belonging to the ESKAPE family of pathogens (Staphylococcus aureus; vancomycin-resistant Enterococcus faecium; Acinetobacter baumannii; and Klebsiella pneumonia), as well as Escherichia coli. Our results demonstrated broad photodynamic inactivation of all bacterial strains studied upon illumination (30 min; 65 ± 5 mW/cm²; 400-700 nm) by a minimum of 99.9996+% (5.8 log units) regardless of taxonomic classification. PAN-Por(+) also inactivated human adenovirus-5 (~99.8% reduction in PFU/mL) and vesicular stomatitis virus (>7 log units reduction in PFU/mL). When compared to cellulose-based materials employing this same photosensitizer; the higher levels of photodynamic inactivation achieved here with PAN-Por(+) are likely due to the combined effects of higher photosensitizer loading and a greater surface area imparted by the use of nanofibers. These results demonstrate the potential of photosensitizer-embedded polyacrylonitrile nanofibers to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.

Electrospun Polyacrylonitrile-Ionic Liquid Nanofibers for Superior PM2.5 Capture Capacity

Ambient fine particulate matter (PM) affects both human health and climate. To reduce the PM2.5 (mass of particles below 2.5 μm in diameter) concentration of an individual's living environment, ionic liquid-modified polyacrylonitrile (PAN) nanofibers with superior PM2.5 capture capacity were prepared by electrospinning. Ionic liquid diethylammonium dihydrogen phosphate (DEAP) with high viscosity and hydrophilicity was involved during the electrospinning process. Observations by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and water contact angle measurement suggested that the modification of DEAP on PAN effectively altered the morphology (roughness) and surface properties (hydrophilicity) of the PAN nanofibers. The PM2.5 capture measurement was performed in a closed and static system, which mimicked the static hazy weather without wind flow. As a result, DEAP-modified PAN nanofibers exhibited significantly enhanced PM2.5 capture capacity compared to that of the bare PAN nanofibers. This can be attributed to the improved surface roughness (i.e., improved adsorption sites), hydrophilicity, and dipole moment of PAN upon DEAP modification.

Comprehensive Understanding of High Polar Polyacrylonitrile as an Effective Binder for Li-Ion Battery Nano-Si Anodes

Well-defined polyacrylonitriles (PANs) with different molecular weights were synthesized through an activator regenerated by electron-transfer atom-transfer radical polymerization method and employed as binders in silicon negative electrode for lithium-ion batteries. Compared with poly(vinylidene fluoride) and carboxyl methyl cellulose as binders, the electrode performance of PANs is well-improved. Specifically, at 100 mA g(-1) from 0.01 to 1.5 V, the initial discharge capacity of PAN100-based electrode is 4147.8 mA h g(-1) and still remains about 1639.6 mA h g(-1) over 50 cycles. A comprehensive understanding on the improvement mechanism is preliminarily discussed. The results indicate that the superior performance largely depends on the higher lithium ion diffusion efficiency in PAN which results from the weak interaction between lithium ions and PAN polymer chain, and the hydrogen bonds among the nitrile group (C≡N) of PAN, Si nanoparticles, and the current collector, which will lead to an efficient coating of PAN with the Si particles and well-improved adhesion strength, synergistically depressing the structural deterioration of silicon electrodes.

Optimized Silicon Electrode Architecture, Interface, and Microgeometry for Next-Generation Lithium-Ion Batteries

Optimized performance of silicon-ionic- liquid lithium-ion batteries through the implementation of a new electrode-microgeometry. The incorporation of 1D silicon nanowires into the cyclized-polyacrylonitrile-based electrode-architecture allows for greatly improved active material utilization, higher rate capabilities, and reduced interfacial reactions.

Efficient PEDOT:PSS-Free Polymer Solar Cells with an Easily Accessible Polyacrylonitrile Polymer Material as a Novel Solution-Processable Anode Interfacial Layer

We demonstrate that an easily accessible polyacrylonitrile (PAN) polymer can efficiently function as a novel solution-processable anode interfacial layer (AIL) to boost the device performances of polymer:fullerene-based solar cells (PSCs). The PAN thin film was simply prepared with spin-coating of a cost-efficient PAN solution dissolved in dimethylformamide on indium tin oxide (ITO), and the thin polymeric interlayer on PSC parameters and stability were systemically investigated. As a result, the cell efficiency of the PSC with PAN was remarkably enhanced compared to the device using bare ITO. Furthermore, with PAN, we finally achieved an excellent power conversion efficiency (PCE) of 6.7% and a very high PSC stability in PTB7:PC71BM systems, which constitute a highly comparable PCE and superior device lifetime relative to those of conventional PSCs with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (

PEDOT

PSS). These results demonstrate that the inexpensive solution-processed PAN polymer can be an attractive

PEDOT

PSS alternative and is more powerful for achieving better cell performances and lower cost PSC production.

Porous Carbon Nanofibers from Electrospun Biomass Tar/Polyacrylonitrile/Silver Hybrids as Antimicrobial Materials

A novel route to fabricate low-cost porous carbon nanofibers (CNFs) using biomass tar, polyacrylonitrile (PAN), and silver nanoparticles has been demonstrated through electrospinning and subsequent stabilization and carbonization processes. The continuous electrospun nanofibers had average diameters ranging from 392 to 903 nm. The addition of biomass tar resulted in increased fiber diameters, reduced thermal stabilities, and slowed cyclization reactions of PAN in the as-spun nanofibers. After stabilization and carbonization, the resultant CNFs showed more uniformly sized and reduced average diameters (226-507 nm) compared to as-spun nanofibers. The CNFs exhibited high specific surface area (>400 m(2)/g) and microporosity, attributed to the combined effects of phase separations of the tar and PAN and thermal decompositions of tar components. These pore characteristics increased the exposures and contacts of silver nanoparticles to the bacteria including Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, leading to excellent antimicrobial performances of as-spun nanofibers and CNFs. A new strategy is thus provided for utilizing biomass tar as a low-cost precursor to prepare functional CNFs and reduce environmental pollutions associated with direct disposal of tar as an industrial waste.

Gel Spinning of Polyacrylonitrile/Cellulose Nanocrystal Composite Fibers

Polyacrylonitrile (PAN)/cellulose nanocrytal (CNC) fibers containing 0, 1, 5, and 10 wt % CNCs have been successfully produced by gel spinning. The rheological properties of solutions were investigated and the results showed that the complex viscosity and storage modulus of solutions were significantly affected by the presence of CNCs in the solution. Structure, morphology, mechanical properties and dynamic mechanical properties of these fibers have been investigated. Tensile modulus and strength increased from 14.5 to 19.6 GPa and from 624 to 709 MPa, respectively, as CNC loading increased from 0 to 10 wt %. Wide-angle X-ray diffraction results showed better PAN chain alignment and higher PAN crystallinity with the incorporation of CNCs.

Microscale Sensing of Oxygen via Encapsulated Porphyrin Nanofibers: Effect of Indicator and Polymer "Core" Permeability

Biomimetic polymer nanofibers integrate sensing capabilities creating utility across many biological and biomedical applications. We created fibers consisting of either a poly(ether sulfone) (PES) or a polysulfone (PSU) core coated by a biocompatible polycaprolactone (PCL) shell to facilitate cell attachment. Oxygen sensitive luminescent probes Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP) or Pd(II) meso-tetra(pentafluorophenyl)porphine (PdTFPP), were incorporated in the core via single-step coaxial electrospinning providing superior sensitivity, high brightness, linear response, and excellent stability. Both PES-PCL and PSU-PCL fibers provide more uniform probe distribution than polydimethylsiloxane (PDMS). PSU-based sensing fibers possessed optimum sensitivity due to their relatively higher oxygen permeability. During exposure to 100% nitrogen and 100% oxygen, PES-PCL fiber displayed an I0/I100 value of 6.7; PSU-PCL exhibited a value of 8.9 with PtTFPP as the indicator. In contrast, PdTFPP-containing fibers possess higher sensitivity due to the long porphyrin lifetime. The corresponding I0/I100 values were 80.6 and 106.7 for the PES-PCL and PSU-PCL matrices, respectively. The response and recovery times were 0.24/0.39 s for PES-PCL and 0.38/0.83 s for PSU-PCL which are 0.12 and 0.11 s faster, respectively, than the Pt-based porphyrin in the same matrices. Paradoxically, lower oxygen permeabilities make these polymers better suited to measuring higher (i. e., ∼20%) oxygen contents than PDMS. Individual fiber sensing was studied by fluorescence spectrometry and at a sub-micrometer scale by total internal reflection fluorescence (TIRF). Specific polymer blends relate polymer composition to the resulting sensor properties. All compositions displayed linear Stern-Volmer plots; sensitivity could be tailored by matrix or the sensing probe selection.

Ionic conductivity enhancement of polymer electrolytes with ceramic nanowire fillers

Solid-state electrolytes provide substantial improvements to safety and electrochemical stability in lithium-ion batteries when compared with conventional liquid electrolytes, which makes them a promising alternative technology for next-generation high-energy batteries. Currently, the low mobility of lithium ions in solid electrolytes limits their practical application. The ongoing research over the past few decades on dispersing of ceramic nanoparticles into polymer matrix has been proved effective to enhance ionic conductivity although it is challenging to form the efficiency networks of ionic conduction with nanoparticles. In this work, we first report that ceramic nanowire fillers can facilitate formation of such ionic conduction networks in polymer-based solid electrolyte to enhance its ionic conductivity by three orders of magnitude. Polyacrylonitrile-LiClO4 incorporated with 15 wt % Li0.33La0.557TiO3 nanowire composite electrolyte exhibits an unprecedented ionic conductivity of 2.4 × 10(-4) S cm(-1) at room temperature, which is attributed to the fast ion transport on the surfaces of ceramic nanowires acting as conductive network in the polymer matrix. In addition, the ceramic-nanowire filled composite polymer electrolyte shows an enlarged electrochemical stability window in comparison to the one without fillers. The discovery in the present work paves the way for the design of solid ion electrolytes with superior performance.

Polyacrylonitrile fibers containing graphene oxide nanoribbons

Graphene oxide nanoribbon (GONR) made by the oxidative unzipping of multiwalled carbon nanotube was dispersed in dimethylformamide and mixed with polyacrylonitrile (PAN) to fabricate continuous PAN/GONR composite fibers by gel spinning. Subsequently, PAN/GONR composite fibers were stabilized and carbonized in a batch process to fabricate composite carbon fibers. Structure, processing, and properties of the composite precursor and carbon fibers have been studied. This study shows that GONR can be used to make porous precursor and carbon fibers. In addition, GONR also shows the potential to make higher mechanical property carbon fibers than that achieved from PAN precursor only.

Properties investigation of sulfonated poly(ether ether ketone)/polyacrylonitrile acid-base blend membrane for vanadium redox flow battery application

Acid-base blend membrane prepared from sulfonated poly(ether ether ketone) (SPEEK) and polyacrylonitrile (PAN) was detailedly evaluated for vanadium redox flow battery (VRFB) application. SPEEK/PAN blend membrane exhibited dense and homogeneous cross-section morphology as scanning electron microscopy and energy-dispersive X-ray spectroscopy images show. The acid-base interaction of ionic cross-linking and hydrogen bonding between SPEEK and PAN could effectively reduce water uptake, swelling ratio, and vanadium ion permeability, and improve the performance and stability of blend membrane. Because of the good balance of proton conductivity and vanadium ion permeability, blend membrane with 20 wt % PAN (S/PAN-20%) showed higher Coulombic efficiency (96.2% vs 91.1%) and energy efficiency (83.5% vs 78.4%) than Nafion 117 membrane at current density of 80 mA cm(-2) when they were used in VRFB single cell. Besides, S/PAN-20% membrane kept a stable performance during 150 cycles at current density of 80 mA cm(-2) in the cycle life test. Hence the SPEEK/PAN acid-base blend membrane could be used as promising candidate for VRFB application.

Preparation and Characterization of Homopolymer Polyacrylonitrile-Based Fibrous Sorbents for Arsenic Removal

This research investigated the modification of homopolymer polyacrylonitrile (PAN) fibers for use as an adsorbent for removing arsenic from drinking water. Fibers were chemically modified and cross-linked using combinations of hydrazine hydrate and sodium hydroxide (NaOH) before being loaded with ferric hydroxide using two different iron loading procedures. Effects of reagent concentrations and reaction times on degree of chemical modification and fiber properties were investigated using Fourier transform infrared spectroscopy and ion-exchange measurements. Arsenate adsorption was a function of both the iron loading and the properties of the underlying fiber. For fibers treated with only a single reagent, both Fe³⁺ and arsenate adsorption could be understood in terms of ion-exchange properties of the fiber surfaces. However, for fibers treated with both hydrazine and NaOH, the ion-exchange properties of the surface could not explain the Fe³⁺ and arsenate adsorption behavior. The best arsenate removal performance was obtained using the simplest pretreatment procedure of soaking in 10% NaOH at 95°C for 90 min, followed by precipitation coating of ferric hydroxide. This simple preparation procedure involves only two commonly available and inexpensive reagents and can be carried out without any specialized equipment. This suggests that adsorbents based on inexpensive homopolymer PAN fabric may be produced in developing areas of the world where commercial products may not be available.

Molecular level computational studies of polyethylene and polyacrylonitrile composites containing single walled carbon nanotubes: effect of carboxylic acid functionalization on nanotube-polymer interfacial properties

Molecular dynamics (MD) and molecular mechanics (MM) methods have been used to investigate additive-polymer interfacial properties in single walled carbon nanotube (SWNT)—polyethylene and SWNT—polyacrylonitrile composites. Properties such as the interfacial shear stress and bonding energy are similar for the two composites. In contrast, functionalizing the SWNT with carboxylic acid groups leads to an increase in these properties, with a larger increase for the polar polyacrylonitrile composite. Increasing the percentage of carbon atoms that were functionalized from 1 to 5% also leads to an increase in the interfacial properties. In addition, the interfacial properties depend on the location of the functional groups on the SWNT wall.

Synthesis and Thermal Properties of Acrylonitrile/Butyl Acrylate/Fumaronitrile and Acrylonitrile/Ethyl Hexyl Acrylate/Fumaronitrile Terpolymers as a Potential Precursor for Carbon Fiber

A synthesis of acrylonitrile (AN)/butyl acrylate (BA)/fumaronitrile (FN) and AN/EHA (ethyl hexyl acrylate)/FN terpolymers was carried out by redox polymerization using sodium bisulfite (SBS) and potassium persulphate (KPS) as initiator at 40 °C. The effect of comonomers, BA and EHA and termonomer, FN on the glass transition temperature (T_g) and stabilization temperature was studied using Differential Scanning Calorimetry (DSC). The degradation behavior and char yield were obtained by Thermogravimetric Analysis. The conversions of AN, comonomers (BA and EHA) and FN were 55%-71%, 85%-91% and 76%-79%, respectively. It was found that with the same comonomer feed (10%), the T_g of AN/EHA copolymer was lower at 63 °C compared to AN/BA copolymer (70 °C). AN/EHA/FN terpolymer also exhibited a lower T_g at 63 °C when compared to that of the AN/BA/FN terpolymer (67 °C). By incorporating BA and EHA into a PAN system, the char yield was reduced to ~38.0% compared to that of AN (~47.7%). It was found that FN reduced the initial cyclization temperature of AN/BA/FN and AN/EHA/FN terpolymers to 228 and 221 °C, respectively, in comparison to that of AN/BA and AN/EHA copolymers (~260 °C). In addition, FN reduced the heat liberation per unit time during the stabilization process that consequently reduced the emission of volatile group during this process. As a result, the char yields of AN/BA/FN and AN/EHA/FN terpolymers are higher at ~45.1% and ~43.9%, respectively, as compared to those of AN/BA copolymer (37.1%) and AN/EHA copolymer (38.0%).

TiO2@C core-shell nanoparticles formed by polymeric nano-encapsulation

TiO2 semiconducting nanoparticles are known to be photocatalysts of moderate activity due to their high band-gap and high rate of electron-hole recombination. The formation of a shell of carbon around the core of TiO2, i.e., the formation of TiO2@C nanoparticles, is believed to partly alleviate these problems. It is usually achieved by a hydrothermal treatment in a presence of a sugar derivative. We present here a novel method for the formation of highly uniform C shell around TiO2 nanoparticles. For this purpose, TiO2 nanoparticles were dispersed in water using an oligomeric dispersant prepared by Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization. Then the nanoparticles were engaged into an emulsion polymerization of acrylonitrile, resulting in the formation of a shell of polyacrylonitrile (PAN) around each TiO2 nanoparticles. Upon pyrolysis, the PAN was transformed into carbon, resulting in the formation of TiO2@C nanoparticles. The structure of the resulting particles was elucidated by X-Ray diffraction, FTIR, UV-VIS and Raman spectroscopy as well as TEM microscopy. Preliminary results about the use of the TiO2@C particles as photocatalysts for the splitting of water are presented. They indicate that the presence of the C shell is responsible for a significant enhancement of the photocurrent.

Hierarchical porous framework of Si-based electrodes for minimal volumetric expansion

A tunable hierarchical porous framework is fabricated to house the volumetric changes outputted by Si. The nSi@cPAN/cPAN electrodes only expand by 14.3% at full initial lithiation and remain within 23% expansion from its uncycled state after 20 cycles with remarkable cycling stability and high coulombic efficiencies in excess of 99.5%.