PEO Chains Research Articles

Synthesis of superhydrophilic Gradient-Like Copolymers: Kinetics of the RAFT copolymerization of methacryloyloxyethyl phosphorylcholine with PEO methacrylate

Brush copolymers containing PEO side chains and zwitterionic units of 2-methacryloyloxyethyl phosphorylcholine (MPC) were synthesized by RAFT copolymerization with an especial attention to compositional microstructure of the copolymers. Two complementary methods – size exclusion chromatography (SEC) and 1H NMR spectroscopy – were used to study the kinetics of the RAFT copolymerization of MPC (M1) and the macromonomer poly(ethylene oxide) methyl ether methacrylate with medium-length PEO chain (PEOMEMA, M2) in methanol–water mixed solutions. Analysis of the reaction mixtures by the two methods allowed concluding that in mixed solutions of methanol and water, every molecule of MPC carries about 15 molecules of water as an integral part of the monomer. Monomer reactivity ratios calculated by the method of Meyer and Lowry were r1 = 2.48 and r2 = 0.40. The dependences of the copolymer composition on monomer conversion determined experimentally and calculated by the terminal model of free-radical copolymerization differed significantly, demonstrating the specific impact of the mechanism of RAFT on the distribution of copolymer compositions. The copolymers p(MPC-co-PEOMEMA) possessed strongly expressed gradient microstructure, and were characterized by moderately low dispersity (Ð < 1.3). The copolymers showed evident superhydrophilicity with a water contact angle of about 7° and, like pMPC, exhibited cononsolvency in water–ethanol mixed solutions.

Structure and Transport Properties of Poly(ethylene oxide)-Based Cross-Linked Polymer Electrolytes─A Molecular Dynamics Simulations Study

We present an extensive molecular dynamics (MD) simulation study of poly(ethylene oxide) (PEO) based densely cross-linked polymers, focussing on structural properties as well as the systems dynamics in the presence of lithium salt. Motivated by experimental findings for networks with short PEO strands we employ a combination of LiTFSI (Lithium bis(trifluoromethanesulfonyl)imide) and LiDFOB (Lithium difluoro(oxalato)borate). Recently, it has been shown that such multi-salt systems outperform classical single salt systems (Shaji et al., Energy Storage Materials, 2022, 44, 263). To analyse the microscopic scenario we employ an analytical model, originally developed for non-cross-linked polymer electrolytes or blends (Maitra et al., Phys. Rev. Lett., 2007, 98, 227802 and Diddens et al., J. Electrochem. Soc., 2017, 164, E3225-E3231). Excluding very short PEO strands, the local dynamics is only slightly restricted compared to linear PEO and is not significantly dependent on the network structure. The transfer of lithium ions between PEO chains and the motion along the polymer backbone may be controlled through the employed salt.

Adsorption of Peptides onto Carbon Nanotubes Grafted with Poly(ethylene Oxide) Chains: A Molecular Dynamics Simulation Study.

Carbon nanotubes (CNTs) display exceptional properties that predispose them to wide use in technological or biomedical applications. To remove the toxicity of CNTs and to protect them against undesired protein adsorption, coverage of the CNT sidewall with poly(ethylene oxide) (PEO) is often considered. However, controversial results on the antifouling effectiveness of PEO layers have been reported so far. In this work, the interactions of pristine CNT and CNT covered with the PEO chains at different grafting densities with polyglycine, polyserine, and polyvaline are studied using molecular dynamics simulations in vacuum, water, and saline environments. The peptides are adsorbed on CNT in all investigated systems; however, the adsorption strength is reduced in aqueous environments. Save for one case, addition of NaCl at a physiological concentration to water does not appreciably influence the adsorption and structure of the peptides or the grafted PEO layer. It turns out that the flexibility of the peptide backbone allows the peptide to adopt more asymmetric conformations which may be inserted deeper into the grafted PEO layer. Water molecules disrupt the internal hydrogen bonds in the peptides, as well as the hydrogen bonds formed between the peptides and the PEO chains.

Anisotropic ionic transport properties in solid PEO based electrolytes

Solid polymer electrolytes (SPE) based on dry poly(ethylene oxide) (PEO) are interesting candidates to develop solid-state lithium (Li) batteries thanks to their stability toward Li metal anode, mechanical properties and flexibility, as well as ionic conductivity high enough for a battery application at temperatures higher than the PEO melting temperatures. To optimize the ionic conductivity, one strategy is to favor in-plane conductivity thanks to its typical higher value in PEO homopolymer electrolyte compared to the through-plane one. Thus, there is the need to understand the in-plane ionic transport properties (ionic conductivity, transference number, and diffusion coefficient) of SPEs depending on their nature and architecture. Indeed, ionic transport in PEO based SPE is due to a complex interplay between different local mechanisms involving the interaction between the PEO chain segments and both cations and anions. The separation of the cationic and anionic mechanisms is thus necessary to distinguish their contributions on the ionic transport anisotropies. Here, we report on the determination by electrochemical methodologies of the cationic and anionic in-plane ionic conductivities, transference numbers and restricted diffusion coefficients for a series of SPEs made of PEO homopolymers (linear), composite (PEO with the addition of nanocellulose), binary (PS-PEO-PS) and single-ion (PSTFSI-PEO-PSTFSI) conducting triblock copolymer electrolytes. The methodology to get each parameter is presented and discussed while COMSOL simulations permit to take into account the geometries of the in-plane cell (positions of the electrodes and SPE dimension). In addition, an analytical model is presented to fit the experimental data of the in-plane cell relaxation (diffusion regime) with a simple equation to determine the in-plane ambipolar diffusion coefficient. We observed that the in-plane anionic transport in SPEs is strongly hindered by the presence of structural blocks leading to an overall in-plane conductivity lower than the through-plane one.

Dynamics of Polymer Chains in Poly(ethylene oxide)/Silica Nanocomposites via a Combined Computational and Experimental Approach.

The dynamics of polymer chains in poly(ethylene oxide)/silica (PEO/SiO2) nanoparticle nanohybrids have been investigated via a combined computational and experimental approach involving atomistic molecular dynamics simulations and dielectric relaxation spectroscopy (DRS) measurements. The complementarity of the approaches allows us to study systems with different polymer molecular weights, nanoparticle radii, and compositions across a broad range of temperatures. We study the effects of spatial confinement, which is induced by the nanoparticles, and chain adsorption on the polymer's structure and dynamics. The investigation of the static properties of the nanocomposites via detailed atomistic simulations revealed a heterogeneous polymer density layer at the vicinity of the PEO/SiO2 interface that exhibited an intense maximum close to the inorganic surface, whereas the bulk density was reached for distances ∼1-1.2 nm away from the nanoparticle. For small volume fractions of nanoparticles, the polymer dynamics, probed by the atomistic simulations of low-molecular-weight chains at high temperatures, are consistent with the presence of a thin adsorbed layer that exhibits slow dynamics, with the dynamics far away from the nanoparticle being similar to those in the bulk. However, for high volume fractions of nanoparticles (strong confinement), the dynamics of all polymer chains were predicted slower than that in the bulk. On the other hand, similar dynamics were found experimentally for both the local β-process and the segmental dynamics for high-molecular-weight systems measured at temperatures below the melting temperature of the polymer, which were probed by DRS. These differences can be attributed to various parameters, including systems of different molecular weights and nanoparticle states of dispersion, the different temperature range studied by the different methods, the potential presence of a reduced-mobility PEO/SiO2 interfacial layer that does not contribute to the dielectric spectrum, and the presence of amorphous-crystalline interfaces in the experimental samples that may lead to a different dynamical behaviors of the PEO chains.

In-situ construction of high-temperature-resistant 3D composite polymer electrolyte membranes towards high-performance all-solid-state lithium metal batteries

Enabling solid polymer electrolytes (SPEs) with enhanced electrochemical properties and high-temperature-resistance is highly desirable for developing high-performance lithium metal batteries (LMBs) with high-safety. In this contribution, single-ion conducting polymers and SiO2 particles, as advanced fillers, are in-situ cross-linked in poly(ethylene oxide) (PEO) based SPEs to form three-dimensional (3D) cross-linking inorganic/organic composite SPEs. Benefiting from the hydrogen bond interaction between the additives and PEO chains, the crystallinity of PEO polymers in the resultant SPEs is greatly decreased, giving rise to high conductivity (3.3 × 10−4 S cm−1) and lithium ion transference number (0.60) at 60 °C. The Li/Li symmetrical cells with the composite SPEs can be run stably more than 400 h at 60 °C and 550 h at 120 °C under 0.1 mA cm−2, respectively. Remarkably, the favorable thermal stability of composite SPEs leads to safer solid-state LMBs operating at the high temperature up to 120 °C, where it reaches an outstanding rate performance up to 4C and displays impressive cycling performances with 89.9% retention over 110 cycles at 1C. This work offers tremendous potential in the practical application of dendrite-free and high-performance LMBs.

Cost-efficient polyurea carrier for precise control of an anti-inflammatory drug loading and release

In this paper, we present a cost-efficient and reliable route to produce polyurea xerogel (PolyU) as a versatile carrier that provides a high drug loading and offers a tuning over diclofenac (DCF) release profile. A simple one-pot reaction of an amino-terminated-polyether-PEO and a crosslinker, hexamethylene diisocyanate trimer-HDI, allow us to obtain the polymeric networks. The gelation time during the sol-gel reactions (hydrolysis and condensation) can be modulated from minutes to hours by using acetone as solvent to achieve a decrease of reactivity between amine groups from PEO with isocyanate from HDI crosslinker. The interactions of PolyU networks and DCF drug was in depth evaluated by Fourier Transform Infrared Spectroscopy (FTIR), small angle X-ray scattering (SAXS) and computational studies. Analysis performed by differential scanning calorimetry (DSC) have confirmed the inhibition of crystalline moities of PEO by drug interactions with the PEO chains. PolyU was investigated in cell toxicity studies, showing no significant cytotoxicity against the CHO–K1 cell line. Considering the abundance of raw materials and cost-efficient for polyurea preparation, this work clearly opens up high prospects and provides a solution for scaling up the fabrication of new functional devices (contact lenses, patches, thin films, etc) with broad applications in the medical/health fields.

Impact of zinc salt counterion on poly(ethylene oxide) solution viscosity, conductivity, and ability to generate electrospun MOF/nanofiber composites

The effect of seeding poly(ethylene oxide), PEO, aqueous solutions with zinc acetate (ZA) and zinc chloride (ZC) on solution properties (e.g., viscosity and electrical conductivity) and the ability to electrospin nanofibers was investigated. The impacts of the type of Zn counterion and overall salt concentration on solution viscosity and electrical conductivity were correlated to the ability to electrospin nanofibers, as well as the resulting fiber morphology. In dilute PEO solutions, Zn salt addition reduced the PEO hydrodynamic radius ( R h ) and viscosity likely as a result of PEO chain envelopment of Zn cations, while in semi-dilute entangled regimes, Zn salt addition increased R h and viscosity likely due to interactions a single Zn cation with multiple polymer chains. The addition of Zn salts had limited effects on the overlap concentration ( c* ), but increased the entanglement concentration ( c e ), and the presence of either ZA or ZC enabled electrospinning of bead-free fibers at lower PEO concentrations (than without salt) because of the increased electrical conductivity of the solution. However, increasing the ZA concentration in solution had limited effect on fiber diameter and morphology, while raising the ZC concentration in solution resulted in the fusion of fibers into webs and films likely due to charge carryover. The resulting salt-doped PEO nanofibers were used as a template to synthesize a zeolitic imidazolate framework, ZIF-8, through a vapor-deposition approach exploiting the embedded Zn as nucleation sites for heterogeneous growth in a ‘Fiber-first’ strategy. • Aqueous poly(ethylene oxide) solutions were seeded with zinc salts. • Zinc salts, notably Zn acetate, reduced polymer concentration required to spin bead-free fibers. • Zinc chloride, especially at higher loadings, led to electrospun fused webs instead of fibers. • Zinc counterion type impacted solution conductivity and affected bead-free fiber development. • Zinc salt seeding enabled the vapor-phase growth of the zeolitic imidazolate framework ZIF-8.

Dual control of external surface and internal pore structure of small ordered mesoporous silica particles directed by mixed polyion complex micelles

A versatile approach has been developed to prepare small mesoporous silica particles with simultaneous control of the internal ordered pore structure and the external particle surface. Mixed polyion complex (PIC) micelles are used as silica structure-directing agents: they result from the complexation of a polybase with two polyacid double-hydrophilic block copolymers (DHBC) having either a poly(ethylene oxide) (PEO) based-block or a polyacrylamide (PAM) block. The ionizable block in both DHBC is poly(acrylic acid), which complexes oligochitosan to form the core of the electrostatic complex. By varying the architecture of the PEO-based block (linear or comb-shaped) and the synthesis parameters, it is possible to modulate the pore structure from 3D cage-like to 2D-hexagonal and lamellar mesostructures. Replacing a fraction of the PEO-based polymers with DHBC having a polyacrylamide block that has no affinity for silica is shown to affect silica-micelle interactions and material growth. While the PEO chains interact with silica to form the hybrid interface, the PAM chains act as capping agents and control the external surface of the particles. Increasing the relative amount of PAM-based DHBC leads to the formation of small discrete mesoporous silica particles that are reduced in size to 200 nm. The particle size reduction and particle surface stabilization by PAM chains can be explained by considering not only the existence of a mixed corona of PAM and PEO in PIC micelles but also the differentiated solubility of these two neutral blocks induced by silica condensation. Thus, the present strategy allows independent decrease of the particle size and tuning of its pore structure.

Preparation of spiro-shaped multicyclic polymer by combination of ATRP, CuAAC and photo-induced coupling

This paper elaborated the preparation of spiro-shaped multicyclic polymer with repeating heterocyclics. Block copolymer PEO-PS-Br was prepared by atom transfer radical polymerization (ATRP) of styrene (St) with a poly(ethylene oxide) telechelic macroinitiator PEO-Cou-Br, in which both ends of PEO chain were capped by coumarin groups in advance. After azidation of terminal bromine, bimolecular cyclization was conducted with a diyne as difunctional linker to provide heterocyclic polymer with coumarin groups at the boundaries between PEO and PS blocks. The heterocyclic polymer was exposed to UV irradiation at 365 nm to afford spiro-shaped multicyclic polymer via dimerization of coumarin. GPC, 1H NMR and FT-IR were used to characterize obtained products. Photocleavage of multicyclic polymer under irradiation of 254 nm was also investigated, and GPC trace suggests the successful cleavage from spiro-shaped structure to monocycles.

Foldable nano-Li2MnO3 integrated composite polymer solid electrolyte for all-solid-state Li metal batteries with stable interface

All-solid-state lithium-ion batteries (ASSLBs) are considered as the most promising next-generation energy storage devices. In this work, a low-cost foldable nano-Li2MnO3 integrated Poly (ethylene oxide) (PEO) based composite polymer solid electrolyte (CPSE) is prepared by simply solid-phase method. Density functional theory calculations indicate that the LMO could provide faster ion transfer channels for the migration of lithium ions between PEO chains and segments. As such, the CPSE obtained has a high ionic conductivity of 5.1 × 10−4 S cm−1 at 60 °C with a high lithium ions transference number of 0.5. The CPSE remains stable even at high temperature with no heat escaping. This could improve the safety performance of the batteries. As a result, the lithium metal battery assembled with CPSE works stably after over 200 cycles at a high rate of 0.5C, and its specific capacity is as high as 125 mAh g−1. Also, it is confirmed that this CPSE adapts to three cathode materials. The Li metal pouch battery assembled with the CPSE is foldable and has excellent mechanical properties. All these results indicate that the CPSE obtained has excellent electrochemical and outstanding safety performances, which can make it have broad commercial applications in ASSLBs.

A Cross-Linked Poly(Ethylene Oxide)-Based Electrolyte for All-Solid-State Lithium Metal Batteries With Long Cycling Stability

A cross-linked poly(ethylene oxide) (PEO)-based electrolyte with polyaryl polymethylene isocyanate (PAPI) as the cross-linking agent is synthesized by a facile one-pot reaction. The PEO chains are cross-linked by PAPI through the reaction between hydroxyl groups (−OH) and isocyanate groups (−N=C=O). The effects of PAPI on the electrochemical performance of the PEO-based electrolyte and the stability of the electrolyte/electrode interface are investigated. The PEO–PAPI electrolyte has an ionic conductivity of 9.3 × 10–5−1.3 × 10–4 S cm−1 at 60°C. The cross-linked PEO–PAPI electrolyte exhibits enhanced mechanical properties compared to pristine PEO and shows good compatibility with a lithium (Li) metal anode. An all-solid-state Li metal battery (ASSLMB) with the optimized PEO–PAPI electrolyte and a LiFePO4 cathode (1.62 mg cm−2 in mass loading) shows a discharge capacity of 112.8 mAh g−1 after 700 cycles with a current density of 88 μA cm−2 at 60°C. Even with a high mass loading of 8.4 mg cm−2, the ASSLMB with the cross-linked PEO-based electrolyte shows a good cycle performance. The experimental data show that the cross-linked PEO–PAPI electrolyte is a promising candidate for solid electrolytes used in ASSLMBs.

Poly(ethylene oxide) Is Positively Charged in Aqueous Solutions.

There have been controversies about the binding of cations to poly(ethylene oxide) (PEO) chains in aqueous solutions. In the current study, single molecular evidence of charging PEO chains by cation binding in aqueous solutions is provided. From the adoption of the photon-counting histogram method, it is discovered that the local pH value at the vicinity of the PEO chain is higher than the bulk solution, showing that the PEO chain is positively charged. Such a situation exists with and without the presence of salt (NaCl) in the solution, presumably due to the binding of cations, such as hydronium and sodium ions. Single molecular electrophoresis experiments using fluorescence correlation spectroscopy demonstrate that the PEO chains are weakly charged with a charging extent of ~5%. In comparison to the salt-free condition, the addition of external salt (NaCl) at moderate concentrations further charges the chain. The charging causes the PEO chains to expand and a further increase in the salt concentration causes the chain to shrink, exhibiting a polyelectrolyte-like behavior, demonstrated by the hydrodynamic radii of a single PEO chain. The effect of ion identity is discovered with alkali cations, with the order of the charging capacity of Li+ < Na+ < Cs+ < K+.

Build up ‘highway’ in membrane via solvothermal annealing for high-efficient CO2 capture

Poly (ethylene oxide) (PEO) membranes are attractive for CO2 capture due to the particular dipolar–quadrupolar interaction between EO units and CO2 molecules, which offer high CO2/N2 selectivity. However, the low CO2 permeability of PEO membranes hampers their practical applications. Herein, a simple solvothermal annealing approach was proposed to enhance the flexibility of PEO chains via ‘activating’ the disengagement and rearrangement of side chains, which is essential for boosting the gas permeability. The effects of solvothermal annealing temperature, time, and solvent on the CO2/N2 separation performance were comprehensively investigated. The mechanism for the performance enhancement was proposed: a “highway” for gas transportation was built up by the released flexible side chains, which were confirmed by the mechanical and Li ion conductivity characterizations. The optimized PEO membrane offers a superior CO2 permeability of 1294 Barrer, a high CO2/N2 selectivity of 50, and 110-h long-term running stability, being beyond the 2008 Robeson’s upper bound line and promoting the practical application of PEO membranes in CO2 capture by reducing the cost.

Molecular dynamics study on lithium‐ion transport in PEO branched nanopores with PYR14TFSI ionic liquid

AbstractLithium ion transport in a poly‐(ethylene oxide) (PEO) branched nanopore filled with a solution of [lithium][bis(trifluoromethanesulfonyl)imide]/[1‐butyl‐1‐methylpyrrolidinium][bis(trifluoromethanesulfonyl)imide] (LiTFSI/PYR14TFSI) was investigated by molecular dynamics using many‐body polarizable force field. The structural and dynamic properties of lithium ions in the nanopores with different sizes and ratios of ions to PEO chains were examined. The first coordination shell of the lithium ions had a lower intensity in the longitudinal direction than in the radial direction. Cluster analysis of [Lix(TFSI)n]−(n−x)showed the absence of large lithium clusters (x ≥ 2) as a result of the enhanced suppression of monodentate structures compared with binary electrolytes (i.e., LiTFSI/PYR14TFSI without PEO chains). The emergence of [Li(TFSI)2]−and its relatively small hydrodynamic radius facilitated rapid dynamics compared with binary electrolytes. The diffusion coefficients and ionic conductivities of the lithium ions in the longitudinal direction increased with an increase in the ratio of the ions to PEO chains and a decrease in the pore size. It was noted that the lithium‐ion transport was mainly governed by structural diffusion based on a shorter residual time for anions compared with binary electrolytes. In addition, single ion trajectory analysis was performed and more frequent anion exchanges were observed when PEO chains were introduced.

Bifunctional LiI additive for poly(ethylene oxide) electrolyte with high ionic conductivity and stable interfacial chemistry

The development of polymer-based solid-state batteries is severely limited by the low ionic conductivity of solid polymer electrolyte and the instable interface between polymer electrolyte and Li-metal anode. In this work, lithium iodide (LiI) as a bifunctional additive was introduced into the poly(ethylene oxide) (PEO)-based electrolyte to improve the ionic conductivity and to construct a stable interphase at the Li/PEO interface. I− anions offer a strong electrostatic interaction with hydrogen atoms on PEO chains (HPEO) and forming massive I–H bonds that cross-link PEO chains, decrease crystallinity of PEO, and thus improve Li+ interchain transport. In addition, LiI participates in the formation of an inorganic-rich interphase layer, which decreases the energy barrier of Li+ transport across the interface and thus inhibits the growth of lithium dendrites. As a result, the composite PEO electrolyte with 2 wt% LiI (PEO-2LiI) presents a very high ionic conductivity of 2.1 × 10−4 S cm−1 and a critical current density of 2.0 mA cm−2 at 45 °C. Li symmetric cell with this PEO-2LiI electrolyte exhibits a long-term cyclability over 600 h at 0.2 mA cm−2. Furthermore, solid-state LiFePO4 and LiNi0.8Mn0.1Co0.1O2 batteries with the PEO-2LiI electrolyte show an impressive electrochemical performance with outstanding cycling stability and rate capability at 45 °C.

Polymeric Surfactant P84/Polyoxometalate α-PW12O403−—A Model System to Investigate the Interplay between Chaotropic and Hydrophobic Effects

Low charge density nanometric ions were recently shown to bind strongly to neutral hydrated matter in aqueous solution. This phenomenon, called the (super-)chaotropic effect, arises from the partial dehydration of both the nano-ion and the solute, leading to a significant gain in enthalpy. Here, we investigate the chaotropic effect of the polyoxometalate α-PW12O403− on the triblock copolymer P84: (EO)19(PO)43(EO)19 with (EO)19 the polyethoxylated and (PO)43 the polypropoxylated chains. The combination of phase diagrams, spectroscopic (nuclear magnetic resonance) and scattering (small angle neutron/X-ray scattering) techniques revealed that: (i) below the micellization temperature of P84, PW12O403− exclusively binds to the propylene oxide moiety of P84 unimers; and (ii) above the micellization temperature, PW12O403− mostly adsorbs on the ethylene oxide micellar corona. The preferential binding of the PW12O403− to the PPO chain over the PEO chains suggests that the binding is driven by the chaotropic effect and is reinforced by the hydrophobic effect. At higher temperatures, copolymer micellization leads to the displacement of PW12O403− from the PPO chain to the PEO chains. This study deepens our understanding of the subtle interplay between the chaotropic and hydrophobic effects in complex salt-organic matter solutions.

PREPARATION AND CHARACTERIZATION OF NON-WOVEN NANOFIBROUS MEMBRANES OF CHITOSAN AND POLY(ETHYLENE OXIDE) IN A HIGH ETHANOL CONCENTRATION

The potential use of non-woven fibrous membranes of chitosan (CS) and poly(ethylene oxide) (PEO) in the filtering system application has appealed to the worldwide research concern. However, CS and PEO solution blends and the CS nanoparticles (CSNPs)-PEO suspensions using a high concentration of ethanol as the PEO solvent with a low CS/PEO ratio have not been studied. CS in 2% acetic acid solution and PEO in 96% ethanol blends were electrospun to form fibrous membranes. The CS concentration in acetic acid varied by 0, 0.5, 1.0, and 1.5 wt.%, and a CS/PEO ratio was 10/90. The addition of 0.5 and 1.0 wt.% CSNPs to PEO solution was used for comparison. The current research aims to explore the impact of CS concentration on the physical and mechanical properties of the CS/PEO non-woven fibrous membranes. CS solution's effect on the fiber morphology and mechanical property is compared to that of CSNPs. Visual observation demonstrated a wrinkle pattern formed on almost all the nanofibrous membranes due to a high evaporation rate of the used PEO solvent. However, the fiber morphology of the membranes was not significantly affected. Differential scanning calorimetric (DSC) analysis indicates that the degree of crystallinity increases with CS concentration. It corresponds to the improvement of the tensile strength of the CS/PEO membranes, especially by adding 1.5% CS concentration. Nonetheless, CSNPs loading improves tensile strength of CSNPs/PEO higher than that of CS/PEO at the same CS concentration. Introducing CSNPs to the PEO crystal structure can improve the crystallinity higher than by inducing intermolecular hydrogen bonding of CS and PEO chains.

3D reactive printing of polyaniline hybrid hydrogel microlattices with large stretchability and high fatigue resistance for wearable pressure sensors

Conducting polymer hydrogels face difficulties in the combination of high elasticity, large sensitivity and wide response range for flexible pressure sensing. Herein, an intrinsically stretchable polyaniline hybrid hydrogel (PHH) is prepared through a reactive shaping method including two steps. First, a high-viscosity precursor solution containing poly(acrylic acid) (PAA), poly(ethylene oxide) (PEO) and aniline monomers is submerged into an acid solution containing initiators for the polymerization of aniline, and gelation is quickly formed due to the formation of dense hydrogen bonds between the PAA and PEO chains. Second, the initiators in the acid solution facilitate subsequent in-situ polymerization of aniline confined in the PAA/PEO framework into a 3D polyaniline (PANI) network. Benefiting from the formation of reversible hydrogen bonds and electrostatic interactions between the PAA/PEO and PANI networks, the resultant PHH exhibits large stretchability and high fatigue resistance. The reactive shaping method facilitates a 3D reactive printing of PHH into pre-designed microlattice structures with high elasticity and electron/ion dual-conducting pathways, which is promising as a stretchable conductor for capacitive pressure sensors. The sensors therefore display high sensitivity (7.10 kPa−1) in a wide detecting range and are capable of detecting complex human motions for wearable sensing applications.

Lithium ion transport in solid polymer electrolyte filled with alumina nanoparticles

The addition of Al2O3 enhances Li+ transport along the PEO chains and provides an additional Li+ transport path, thereby significantly improving the conductivity.