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Patterning nanocrystals in polymer films is essential for the widespread use of nanocrystals in various fields from optics to electronics; therefore, the development of patterning methods for nanocrystals is an important task. Here, we report a unique approach for patterning silver nanowires (AgNWs) using a thermodynamic driving force induced by transient concentration gradients in reaction mixtures. The procedure starts with the preparation of a photocurable monomer solution containing homogeneously dispersed AgNWs. Ultraviolet illumination through a straight-line mask reduces the polymerization rate of monomers in the masked area, decreasing the polymer concentration in comparison with that in the unmasked area. Such transient polymer concentration gradients yield imbalances in the chemical potentials of AgNWs, inducing the migration of AgNWs to form a straight-line pattern of AgNWs. The pattern of AgNWs was visualized via photoluminescence imaging under a laser scanning confocal microscope and compared with the light patterns applied to the mixture. These observations revealed that the magnitude of the AgNW migration is enhanced as the transient concentration gradient increases by thickening the mask to decrease the intensity of light passing through the mask. The structural features of the AgNW pattern were reproduced using numerical simulations based on a set of reaction-diffusion equations, which suggested the key role of the polymerization kinetics characterized by the Trommsdorff-Norrish effect. Moreover, as the AgNW pattern becomes clearer, the electrical resistance along the patterns decreases and more complex patterns can be produced, indicating the potential of the method. Overall, the present patterning method constitutes a simple approach that only requires illumination through a mask to generate the AgNW pattern, which renders it a promising alternative for patterning nanocrystals in polymer films.

The development of methods to pattern nanocrystals with different sizes and shapes remains a challenge. In this study, we demonstrate a unique class of bottom-up approaches to assemble nanocrystals into patterns. Our approach for patterning nanocrystals focuses on the utilization and control of the chemical reaction of solvents surrounding nanocrystals. The photopolymerization of solvent molecules through a photomask creates time-dependent concentration gradients of the solvents. Dispersed nanocrystals such as silver nanowires (AgNWs) migrate and are gradually organized and integrated into the polymerizing films based on the concentration gradients. The AgNW-embedded film properties are determined by the organized AgNW structures and include light transmission and electrical conductivity. Overall, the demonstrated method is very simple, widely applicable to various nanocrystals and solvents, and can thus contribute to the development of a new class of nanocrystal patterning methods.

Carbon black (CB) suspension exhibits various structures depending on the properties of solvent and dispersant as well as the preparation process of suspension. In most cases, CB particles do not exist as independent nanoparticles but as aggregates or agglomerates. In order to evaluate the size distribution at different level of hierarchal structure, we carried out static/dynamic ultrasound scattering analysis for the CB suspensions in alcohol and/or water with or without Nafion, a perfluorinated polymer. The potential of the dynamic ultrasound scattering technique was demonstrated by discriminating diffusing nanoparticles and micron-sized aggregates/agglomerates without dilution of the sample. Particularly, suppression of large agglomerates by addition of Nafion was clearly observed. Phosphotungstic acid (PWA), a family of polyoxometalate, was also employed to obtain smaller unit structures of the CB particles without formation of aggregation after decomposition of CB. The possible structures of the CB/PWA suspensions with and without Nafion were also discussed.

Interpenetrating polymer networks (IPNs) with spatially graded co-continuous structures were constructed by photo-cross-linking a homogeneous mixture of photo-reactive polystyrene and methyl methacrylate monomer. For a given thickness, irradiation with weak ultraviolet (UV) light results in a co-continuous morphology uniform throughout the sample. However, as the irradiation intensity increases to some certain extent, spatially graded co-continuous morphology in the micrometre scales emerges due to the significant effect of the gradient of the light intensity along the irradiation direction. These 3-dimensional graded structures were observed by using laser scanning confocal microscopy (LSCM) and were analyzed by digital image analysis. The depth dependence of these graded structures can be well expressed by a power law with an exponent depending strongly on the irradiation intensity. The time-evolution of the graded morphology was monitored at different depths of the same irradiated sample. It was found that the phase separation does not follow conventional laws of kinetics, but instead exhibits the autocatalytic behavior, reflecting the effects of the heat produced by the photopolymerization of MMA monomer on the phase separation process. The experimental data obtained in this study suggest a method of producing polymeric materials with spatially graded structures in the micrometer scales by solely changing the irradiation intensity.

In this study, we demonstrate that vertically aligned gold nanowire array electrodes provide rapid ion and electron transport to the electrode-electrolyte interface. The charge-transport properties of the nanowire electrodes were investigated through cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy under a constant-volume device configuration. The total charge stored in the corresponding devices increases monotonically with the length of the nanowires owing to the concomitant increase in the electroactive real surface area of the electrode. A remarkable feature of the electrodes is that the internal resistance associated with charge transport decreases with increasing nanowire length. The electric double-layer capacitance per unit electroactive surface area remains constant up to high charge/discharge rates. Our results demonstrate that charge migration occurs rapidly on the surfaces of the nanowires regardless of their length and the charge/discharge rate used. Thus, vertically aligned nanowire array electrodes show promise as current collectors for next-generation electrochemical energy-storage devices.

The size distribution and the elasticity of thermo-responsive gel particles dispersed in water were examined in-situ by ultrasonic spectroscopy (US). Poly(N-isopropylacrylamide) (PNIPAM) gel particles, undergoing volume phase transition at 34°C were synthesized by redox polymerization in emulsion, and the temperature dependence of the acoustic properties was examined. The longitudinal velocity and the attenuation coefficient of particle exhibited a drastic change at the transition temperature, indicating the increase in the mechanical properties, such the longitudinal, bulk and shear moduli, due to the shrinkage of particles upon temperature stimulation. The shear modulus of monodisperse particles, and also the stiffness of the gel particles were evaluated.

Pickering emulsions comprising liquid droplets stabilized by solid microparticles have gained much attention in the field of cosmetics, inks, and drug delivery systems. To ensure that microparticles in Pickering emulsions are localized at the surface of liquid droplets, ultrasonic spectroscopy analysis combined with scattering function theory was conducted in this study. Two specific cases were investigated: (1) silica particles and liquid droplets independently dispersed in liquid and (2) silica particles effectively localized at the surface of the droplets. It was found that the core-shell model was effective for analyzing nanoparticles anchored at the surface of oil droplets. Conversely, it was found that an effective shell comprised of solid particles was no longer observed as the particle size or the distance between solid particles increased. When a large solid particle was applied, the ultrasonic spectra resembled those of conventional surfactant-stabilized emulsions without solid stabilizers.

The size distribution and mechanical properties of microparticle dispersed in liquid can be characterized by ultrasonic spectroscopy with the aid of acoustic scattering theories. In order to carry out the accurate analysis of the particles, the basic properties, such as the density, viscosity, longitudinal and shear velocities and intrinsic attenuation coefficient of the particle must be known prior to the analysis. Particularly, for soft elastomers or rubbers which exhibit complex mechanical properties with comparable real and imaginary parts, such fundamental information should be provided prior to the particle analysis to minimize the uncertainty of estimation associated with the number of adjustable parameters. In this study, we examined the acoustical properties of poly(methyl methacrylate)(PMMA) and cross-linked poly(dimethyl siloxane) sheets having different cross-linker concentrations by Multiple-Echo Reflection Ultrasonic Spectroscopy which simultaneously enabled us to acquire 4 fundamental properties, the ultrasound attenuation coefficient, phase velocity, density, and thickness (MERUS4 for solid plate). In addition, it was confirmed that the acoustic spectra of PMMA particles dispersed in water were reproduced well with the physical properties determined by MERUS4 using the PMMA plates.

Dynamic ultrasound scattering allows us to investigate the particle motion and its average size via the time-evolution analysis of the scattering amplitude in optically turbid media. Recently, we proposed a novel particle sizing method that simultaneously analyzes the depth dependences on the sedimentation velocity and the scattered intensity without prior knowledge about the shape of the size distribution (Ultrasonics, 65 (2016) 59–68). In this study, the applicability of the technique to Fluorinert/water dilute and concentrated emulsions (up to 40 vol%) was examined. For the bimodal distribution of the emulsion, the size distribution of the particles was successfully obtained by directly probing the particle motion with different sizes as a function of the sample depth. The validity of the analysis was also investigated by comparing with conventional ultrasonic spectroscopy.

Phase separation of polymer mixtures induced by photo-crosslinking and photopolymerization is summarized from the viewpoint of competing interactions in polymeric systems. First, the kinetics of photo-crosslinking and photopolymerization are reviewed with particular emphasis on the Trommsdorff − Norrish effect in polymerization, which leads to the formation of a bimodal distribution of molecular weight at long irradiation time. The emergence of a very large molecular weight and the characteristic time for this effect to set in are utilized as a tool to control the temporal development of the resulting morphology. The shrinkage associated with the reaction and particularly its effect on the phase separation and the morphology are discussed together with the influence of the Trommsdorff − Norrish effect. Experiments on polymerization-induced phase separation extended from binary to ternary mixtures are described where the interfacial interactions give rise to a wide variety of morphologies. Taking advantages of light, experiments using spatial and temporal modulation have been performed to control and manipulate the phase separation. These experimental results are summarized and briefly discussed in relation to the elastic deformation induced by polymerization. Finally, an overview of theoretical studies and numerical simulation of reaction-induced phase separation is given with some comments on the complexity of the phenomena. © 2016 Society of Chemical Industry

A novel ultrasound technique called Frequency-Domain Dynamic ultraSound Scattering (FD-DSS) was employed to determine sedimentation velocities and the diameters of microparticles in a highly turbid suspension. The paper describes the importance of the scattering vector q for dynamic scattering experiments using broadband ultrasound pulses because q (or frequency) corresponds to the spatial length scale whereas the pulses involve inevitable uncertainty in the time domain due to the frequency distribution of broadband pulse. The results obtained from Stokes velocity of monodispersed silica and polydivinylbenzene (PDVB) particles were compared to those obtained by a Field Emission Scanning Electron Microscope (FE-SEM). A novel method to extract the particle size distribution is also demonstrated based on an ultrasound scattering theory.

Poly(ethyl acrylate)/poly(methyl methacrylate) (PEA/PMMA) polymer networks (IPNs) with spatially graded bicontinuous morphology were designed and controlled by taking advantage of the spinodal decomposition process induced by photopolymerization of the MMA monomer. Spatial gradients of the quench depth, induced by the gradients of light intensity, were generated along the path of the excitation light travelling through the mixture. Bicontinuous structures with uniaxial gradient of characteristic length scales were obtained by two different methods: simply irradiating the mixture with strong light intensity along the Z-direction and using the so-called computer-assisted irradiation (CAI) method with moderate intensity to generate the light intensity gradient exclusively in the XY plane. These experimental results suggest that the combination of these two irradiation methods could provide polymer materials with biaxially co-continuous gradient morphology. An analysis method using the concept of spatial correlation function was developed to analyze the time-evolution of these graded structures. The experimental results obtained in this study suggest a promising method to design gradient polymers in the bulk state (3D) as well as on the surface (2D) by taking advantage of photopolymerization.

Motivated by many exclusive and useful features of cellulose nanocrystals (CNC) and the underutilized resource of waste newspaper, this study aimed to extract CNC from waste newspapers by means of alkali and bleaching treatments followed by acid hydrolysis. The morphological structure of the obtained CNC was analysed by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) methods. The remarkable removal of surface contamination and the reduction in fiber diameter during alkali and bleaching treatment were observed and the nano-dimension of the extracted CNC was revealed with the average diameter of 12.3 ± 2.8 nm. Characterization of the extracted CNC showed a high whiteness index of 80%, and high transparency of about 80% of the light at 600 nm calculated for a 0.02 mm thick nanocellulose film. Fourier transform infrared spectroscopy (FTIR) indicated that lignin, hemicellulose and other coloring agents were successfully removed. A comparably high crystallinity index of 80.15% was calculated from x-ray diffraction data. Thermogravimetric analysis showed that the product had a typical maximum thermal degradation at 300 °C. The analysis results indicated the successful extraction of good CNC from waste newspaper with the shortest processing time ever reported for acid hydrolysis with conventional alkali and bleaching pretreatment. The findings also strongly support for further research of nanocomposites reinforced by CNC produced from waste newspaper.

Ultrasound attenuation coefficient and phase velocity of moderately concentrated suspensions of charged silica particles were measured as a function of frequency. The attenuation coefficients were found to be significantly smaller than the theoretical prediction, and such a difference did not appear in the neutral particle suspensions under the corresponding concentrations. In this study, we have investigated the acoustic spectra of silica particles with different particle sizes, concentrations as well as salt concentrations. It was revealed that the noticeable deviation from the theoretical estimation only appeared in the case of large particle sizes close to the wavelength of ultrasound, and could be circumvented by addition of small amount of salt to suppress the electrostatic interactions of the charged silica particles.

Nanostructured electrodes are at the forefront of advanced materials research, and have been studied extensively in the context of their potential applications in energy storage and conversion. Here, we report on the properties of core–shell (gold-polypyrrole) hybrid nanowires and their suitability as electrodes in electrochemical capacitors and as electrocatalysts. In general, the specific capacitance of electrochemical capacitors can be increased by faradaic reactions, but their charge transfer resistance impedes charge transport, decreasing the capacitance with increasing charge/discharge rate. The specific capacitance of the hybrid electrodes is enhanced due to the pseudocapacitance of the polypyrrole shells; moreover, the electrodes operate as an ideal capacitive element and maintain their specific capacitance even at fast charge/discharge rates of 4690 mA/cm3 and 10 V/s. These rates far exceed those of other types of pseudocapacitors, and are even superior to electric double layer-based supercapacit...

Recovery-after-crosslink behavior observed for PEA-A/PEA blends. For PEA in the matrix with molecular weight smaller than the entanglement molecular weight Me, the recovery was observed, whereas the shrinkage continues upon irradiation for PEA with larger molecular weight.

Phase separation of a ternary mixture composed of poly(ethyl acrylate) and poly(ethyl methacrylate) derivatives dissolved in methyl methacrylate monomer was induced and driven by photopolymerization. Upon varying the initial composition of the mixture and the molecular weight of the resulting poly(methyl methacrylate) via changing the light intensity, a wide variety of morphologies ranging from separated double droplets, Janus-like droplets, core–shell, salami, bicontinuous to tricontinuous structures emerged due to the competition between phase separation and polymerization. Among the emerging morphologies, the tricontinuous structures were significant, and the details of the formation process were particularly investigated by using laser-scanning confocal microscopy (LSCM). Time-resolved experiments reveal that these tricontinuous structures were generated via two steps of the consecutive phase separation process. The formation of these tricontinuous structures is discussed with respect to the polymeriz...

Influence of the Trommsdorff–Norrish (T–N) effect on the phase separation of methyl methacrylate (MMA)/poly(ethyl acrylate) (PEA) mixtures undergoing photo-polymerization was examined by a combination of several experimental techniques. By FT-IR spectroscopy, it was found that the polymerization conversion explosively increases at the onset of this T–N effect. The characteristic irradiation time τ at which this effect occurs, strongly depends on the light intensity and gradually shifts to early time as the irradiation intensity increases. The shrinkage of the mixture observed in situ by laser-scanning confocal microscopy exhibits a transition at a particular irradiation time which is slightly longer than the characteristic time τ. By gel permeation chromatography (GPC), it was found that the molecular weight of the resulting PMMA was almost unchanged before τ and suddenly increases about an order of magnitude after the onset of the auto-acceleration effect. Finally, the characteristic length scales of the morphology also quickly increase with irradiation time and are eventually frozen by this T–N effect. These experimental results indicate that the Trommsdorff–Norrish effect plays an important role in the kinetic processes of polymerization-induced phase separation, suggesting an efficient tool to control the morphology of the polymerizing mixture.

Hierarchically structured materials have drawn great attention to the integration of functionalities into a same material. Here, we demonstrate a method in which hierarchical structures of a polymer mixture can be formed and controlled via multiple phase separation mediated by successive UV irradiation through a temporal cessation. The UV irradiation causes the polymerization and the cross-linking of methyl methacrylate and polystyrene, inducing phase separation of the mixture. When the irradiation is ceased upon phase separation and is subsequently repeated after certain duration in the dark, the secondary phase separation is induced within the same mixture. This intermittent irradiation results in polymer films with hierarchical structures, whose feature is controlled by the UV light intensity and can be transformed into multimodal porous membranes and gels.

Pseudocapacitors have been widely studied in the context of their potential applications in portable electronics and energy regeneration. However, the internal resistance within these devices hampers charge transport and limits their performance. As a result, maximum charge/discharge rates are typically limited to a few hundred mV s-1 for pseudocapacitors. Beyond this limit, capacitance rapidly decreases and devices become incapable of storing energy. Here, we design electrodes in which coaxial nanowires made of highly conductive metal cores and pseudocapacitive organic shells are fabricated into a seamless, monolithic, and vertically aligned structure. The design of this structure reduces its internal resistance, and devices fabricated using these electrodes exhibit excellent energy capacity even when charged/discharged at high rates of more than a few hundred mV s-1 . The energy density obtained in these devices corresponds to the maximum energy density predicted by the Trasatti method, and the coaxial-nanowire structure of the electrodes enhances the charge storage capacity and rate capability simultaneously.

Compared with a nano-sized particle, dynamics of a micron-sized particle in a liquid is often associated with sedimentation (or floating) due to its relatively large mass. The motion of more than two particles is dominated by the hydrodynamic interactions, which are known to persist over a fairly long range, e.g., several millimeters, in suspensions. The particle size may be obtained from the dynamic ultrasound scattering (DSS) technique by the analysis of velocity fluctuations, whose origin is believed to take root in the particle-number fluctuations among temporally formed domains involving collective motion of particles with a certain cut-off length. In this study, such collective particle motion in highly turbid solutions was visualized by means of the phase-mode DSS technique with a single element transducer. Quantitative agreement between the velocity fluctuations obtained by the phase- and conventional amplitude-mode analyses was confirmed, followed by examination of the concentration and the particle size dependences on the dynamic structures induced by the long-ranged interactions. It was found that the phase mode-DSS was a promising method to evaluate the time-dependent structures of the micro-particles in highly turbid suspensions.

Sol–gel derived organic–inorganic hybrids containing phosphotungstic acid (PWA) have been prepared previously to obtain proton conductive membranes. However, leaking of PWA was a serious problem to achieve the higher proton conductivity. In this study, polyelectrolyte membranes functionalized with sulfonic acid groups were fabricated by the sol–gel method. Proton conductivity measurements were performed on an impedance analyzer at 80°C/95% RH. The functionalized polyelectrolyte membranes exhibited the proton conductivity σ ∼ 0.9 (S/cm) which was much higher than the previously reported hybrids containing PWA. Although the hybrids exhibited fairly high proton conductivity irrespective to the catalysts used, that under the low relative humidity strongly depends on the catalysts. Among the hybrids prepared in this study, the membrane synthesized with HCl showed outstanding proton conductive properties even at the low humidity thanks to the proton transport channel formed by the swelling of ionic clusters. This fact was confirmed by measuring the ion exchange capacity, water uptake, swelling rate, Fourier transform infrared spectroscopy, atomic force microscopy, and thermogravimetric analysis. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Phase separation driven by photochemical reactions was examined for two types of polymer mixtures: one in the liquid and the other in the bulk state. In the former, monomer of the first polymer was photo-polymerized and simultaneously cross-linked in the presence of the second polymer in the liquid state, whereas in the second system, a polymer was photo-cross-linked in the presence of the second polymer in the bulk state. A combination of measurements techniques including FT-IR, UV–VIS spectrometry, confocal microscopy, light scattering and Mach–Zehnder interferometry was utilized in order to elucidate the stimulus–response behavior of these polymer networks. The shrinkage of the mixtures occurring during the photo-polymerization process was in situ observed under a laser-scanning confocal microscope (LSCM), whereas the deformation process during the cross-link process in the bulk state was in situ followed by using Mach–Zehnder interferometry (MZI). The correlation between the emergence of the hexagonal-phase morphology and the reaction-induced shrinkage in the polymerizing mixtures was discussed from the reaction kinetics and the LSCM data. For the mixture in the bulk state, MZI data provide a reasonable explanation for the mechanism of the anomalous light scattering from the reacting polymer blends. These experimental results are finally discussed in the context of systems with competing interactions.

The deformation associated with the photocuring reaction of an anthracene-labeled polystyrene (PSA) in a miscible blend with poly(vinyl methyl ether) (PVME) was in situ monitored at ambient temperature by using Mach–Zehnder interferometry (MZI).The curing kinetics of a PSA/PVME (30/70) blend was followed by observing the decrease in the absorption of the anthracene moieties upon irradiation using UV–visible spectroscopy. It was found that both the kinetics of the curing and deformation processes can be well described by the modified Kohlrausch–Williams–Watts (KWW) empirical function. The experimental results reveal a strong correlation between the photocuring and deformation processes of the blend. From the dynamic mechanical measurements performed for samples with different irradiation times, it was also found that the deformation process of the blend observed by MZI is controlled by the on-going cross-link-induced glassification process of the mixtures. These experimental results suggest that MZI is a useful technique to monitor in situ the local deformation and relaxation processes in photoreactive polymers.

The glassy dynamics have been investigated using electric capacitance measurements for thin films of poly(2-chlorostyrene). The observed relaxation behavior of the electric capacitance has been analyzed using a new smoothing procedure for the noisy curves and the eigen-coordinates method for the fitting trends obtained in the results of the smoothing procedure. Such analysis has given us a fascinating relaxation function related to the glassy dynamics. New aging curve will give us a chance to understand a proper physical mechanism (related to a possible formation of dynamical self-similar interacting clusters) that can describe this interesting phenomenon. Physical consequences for the recognized relaxation function are discussed.

Polymer mixtures composed of double networks of a polystyrene derivative (PSAF) and poly(methyl methacrylate) (PMMA) were alternatively synthesized by using ultraviolet (UV) and visible (Vis) light. The PSAF networks were generated by UV irradiation to photodimerize the anthracene (A) moieties labeled on the PSAF chains, whereas PMMA networks were produced by photopolymerization of methyl methacrylate (MMA) monomer and the cross-link reaction using ethylene glycol dimethacrylate (EGDMA) under Vis light irradiation. It was found that phase separation process of these networks can be independently induced and promptly controlled by using UV and Vis light. The characteristic length scale distribution of the resulting co-continuous morphology can be well regulated by the UV and Vis light intensity. In order to confirm and utilize the connectivity of the bicontinuous morphology observed by confocal microscopy, a very small amount, 0.1 wt%, of multi-walled carbon nanotubes (MWCNTs) was introduced into the mixture and the current–voltage (I–V) relationship was subsequently examined. Preliminary data show that MWCNTs are preferentially dispersed in the PSAF-rich continuous domains and the whole mixture became electrically conducting, confirming the connectivity of the observed bi-continuous morphology. The experimental data obtained in this study reveal a promising method to design various scaffolds for conducting soft matter taking advantages of photopolymerization-induced phase separation.

A method that combines UV irradiation and pausing was developed to manipulate the regularity and the length scales of the morphology generated by phase separation in full-interpenetrating polymer networks of polystyrene and poly(methyl methacrylate). Upon increasing the pause time of photopolymerization and photo-crosslink processes, the morphology gradually changes from hexagonal-like packing to random structures. The width of the loss tan δ obtained for these phase-separated materials changes with the morphological regularity, suggesting a potential technique for fabrication of mechanical bandgap materials.

The sedimentation velocity and its fluctuations were investigated for polystyrene microspheres with the diameter 3.6−32 μm by high-frequency dynamic ultrasound scattering. A longitudinal broadband transducer centered at the nominal frequency 20 MHz was employed to probe the particle dynamics along the directions parallel and perpendicular to the sedimentation direction in highly turbid solutions. For the former case, the average sedimentation velocity and its variance were obtained since the direction of the scattering vector coincides with that of the particle displacement. Subsequently, the velocities were calculated to estimate the particle diameters. On the other hand, the velocity fluctuations can be solely determined when the wave propagation direction is normal to the gravity because the average displacement is zero. The velocity fluctuations were evaluated as a function of the sample position, and it was found that the significant decrease in the velocity fluctuations near the two cell walls was o...

Deformation in the nanometer scales of photo-crosslinked poly(ethyl acrylate) (PEA) was in situ monitored by Mach-Zehnder interferometry (MZI). Upon irradiation with 365 nm, anthracene labeled on the PEA chains undergoes photodimerization, generating the PEA networks. The cross-link kinetics induced by different light intensities was monitored by using a UV-visible spectrometer. On the other hand, the deformation in the nanometer scales of the photocross-linked polymer was measured in situ by using a Mach-Zehnder interferometer (MZI) under the same experimental conditions. The aging data observed by ceasing irradiation at different stages of the photocuring process reveal a general relationship for the kinetics of aging under different cross-link densities.

Effects of solvent on the microscopic structure and proton conductivity of organic–inorganic hybrids containing heteropolyacid are reported. The organic–inorganic hybrids were prepared by sol–gel synthesis of 1,8-bis(triethoxysilyl)octane (TES-Oct) in the presence of phosphotungstic acid (PWA). The proton conductivity of the membranes prepared under different solvents exhibited greater values in the order methanol