Ionic Groups Research Articles

Germanium-doped hydroxyapatite: Synthesis and characterization of a new substituted apatite

Hydroxyapatite (HAp) is the major component of all boney tissues in mammals. Because of this omnipresence in the living world, HAp possesses an exceptional biocompatibility. The downside of this omnipresence, however, comes in the form of its mild to moderate biological activities. One means of augmenting these activities involves the doping of HAp with foreign ions. Here, the first synthesis and characterization of HAp doped with germanium ions is being reported. Germanium was deliberately integrated into the crystal lattice of HAp in the form of germanate anions. Approximately two thirds of the germanate ions introduced into the hydrothermal solution got incorporated into the HAp lattice, yielding the approximate stoichiometry of Ca10-x(PO4)5.62+y(GeO3)0.38(OH)2-z. Germanates replaced the phosphates of stoichiometric HAp and induced the expansion of the HAp lattice both along the screw axis of the calcium ion hexagons and in the direction parallel to the basal plane. Simultaneously, the larger size and the triple valency of the germanate ion as compared to the smaller and trivalent phosphates prompted the bond distortion and charge compensation through defect formation, which reduced the crystallinity and increased the microstrain of the HAp lattice. Vibrational spectroscopic analyses corroborated these crystallographic effects by demonstrating the enhanced heterogeneity of the environments surrounding the active modes after germanate ions were incorporated into HAp. Conforming to La Châtelier's principle, this reduction of the crystallographic order increased the capacity of the material for integration of adventitious carbonates. However, the inclusion of germanate ions induced a partial shift of these carbonates to the hydroxyl channel sites, thus decreasing the ratio of the B-type carbonation to the A-type carbonation. Introduced into HAp, germanium acted as a superb regulator of the particle size and morphology, enhancing their fineness and uniformity. Inclusion of germanate ions also increased the electrophoretic mobility and hydrodynamic surface charge density of the particles by reducing their size and by inducing a more stochastic distribution of terminal ionic groups due to the bending of the crystal facets. Overall, the doping of HAp with germanate ions facilitated the production of narrowly dispersed nanorods with a moderately enhanced structural disorder and with a pronounced potential for the biomedical niche.

Flexible Sustained Ionogels with Ionic Hyperbranched Polymers for Enhanced Ion-Conduction and Energy Storage.

Flexible and mechanically robust gel-like electrolytes offer enhanced energy storage capabilities, versatility, and safety in batteries and supercapacitors. However, the trade-off between ion conduction and mechanical robustness remains a challenge for these materials. Here, we suggest that the introduction of ionic hyperbranched polymers in structured sustained ionogels will lead to both enhanced ion conduction and mechanical performance because of the hyperbranched polymers' ionically conductive groups and the complementary interfacial interactions with ionic liquids. More specifically, we investigate the effect of hyperbranched polymers with carboxylate terminal groups and imidazolium counterions with various ionic group densities on the properties of ionogels composed of coassembled cellulose nanofibers (CNFs) and cellulose nanocrystals (CNCs) as sustainable open pore frame for ionic liquid immersion. The addition of hyperbranched polymers leads to the formation of highly interconnected openly porous, lightweight, and shape-persistent materials by harnessing hydrogen bonding between the polymers and the CNFs/CNCs "frame". Notably, these materials possess a 2-fold improvement in ionic conductivity combined with many-fold increase in Young's modulus, tensile strength, and toughness, making them comparable to common reinforced nanocomposite materials. Furthermore, the corresponding thin-film gel supercapacitors possess enhanced electrochemical cycling stability upon repeated bending with an 85% capacitance retention after 10 000 cycles, promising new insight in the development of simultaneously conductive and flexible gel electrolytes with sustained performance.

Spirobisindane-Containing Imidazolium Polyimide Ionene: Structural Design and Gas Separation Performance of “Ionic PIMs”

Polymers of intrinsic microporosity (PIMs) have been explored extensively for challenging membrane separation applications. Manipulating microporosity and functionalities of PIM structures has played a major role in the design of membrane materials that can lead to cost-effective CO2 separation processes. Here we have developed a new class of ionenes, in which imidazolium cations are attached (via imides) to spirobisindane groups commonly associated with PIMs yielding a novel ionic-mediated polymer of intrinsic microporosity or “PIM-polyimide ionene” for high-performance CO2 separations. The PIM-polyimide ionene was prepared via Menshutkin reactions between a newly designed spirobisindane-containing bisimidazole monomer and α,α′-dichloro-p-xylene. The resulting thermally and mechanically stable transparent membrane was further studied for its potential utility for CO2 separation. The newly developed PIM-polyimide ionene demonstrated excellent CO2 separation performance relative to other light gases including H2, N2, and CH4. For CO2/CH4 separation, the results surpass the 2008 Robeson upper bound with CO2 permeability of 356.2 barrer and permselectivity of 55. Most notably, the PIM-polyimide ionene membrane outperformed all our previously developed imidazolium ionenes due to the superior CO2 permeability imparted by spirobisindane groups while achieving a comparable performance within the general range of other functionalized PIMs reported in the literature. This unprecedented result of PIM-polyimide ionenes arises from the inclusion of both highly contorted “spiro” centers and the imidazolium cations which precisely alternate in the main chain polymer backbones, resulting in both high diffusivity selectivity and solubility selectivity. It is also noteworthy that PIM-polyimide ionenes exhibited high tolerance against physical aging, as all the gases exhibited very stable permeability and permselectivity values even after a period of 12 months. We hypothesize that the resistance to aging is due to the interactions between ionic groups stabilizing the structure of the polymer matrix, and as such, the ionene microstructure is already close to equilibrium when the membrane is formed. Overall, this is the first example for the integration of PIM structures within the ionene configuration, providing access to potentially numerous novel PIM-ionene materials that can be used in the development of CO2 selective membranes for applications in flue gas, natural gas, and syngas separations.

Structural and mechanistic insights into starch microgel/anthocyanin complex assembly and controlled release performance

We report a self-assembly method for the fabrication of multilayer-starch-based microgels used for anthocyanin encapsulation. Alcohol-heating treatment and ionization reactions were employed to reduce the crystallinity of starch and introduce ionic groups on the molecule to further cross-link it with sodium trimetaphosphate and produce a starch microgel. The molecular interactions between the starch and the anthocyanins facilitated the anthocyanin encapsulation and the starch-microgel/anthocyanin complexes with one, two, and three self-assembled layers were obtained. The Lay-1 microgel exhibited an encapsulation efficiency of 50.1% when the anthocyanin concentration, cross-linking starch concentration, contact time, and temperature were 0.25 mg/mL, 1.5 mg/mL, 3 h, and 40 °C, respectively. An increase in the number of layers resulted in a more compact microgel structure with the zeta potential presenting variations upon structural changes. Furthermore, the encapsulated anthocyanins presented a slow release from Lay-1, while the multilayered microgels (Lay-2 and Lay-3) displayed outstanding encapsulation stability. This study gives an insight on the encapsulation and release of anthocyanins by starch microgels, and provides a novel strategy for the design of starch-based encapsulation materials presenting great stability.

Swelling Behavior of Lipophilic Polyelectrolyte Gels in Organic Solvents−Water or Sea Water Binary Mixtures

AbstractThe recovery of crude oil and volatile organic compounds (VOCs) spilt in the environment is an intractable problem for environmental scientists. In this paper, a new lipophilic polyelectrolyte gel as an absorbent for various volatile chemical compounds is demonstrated. It is prepared by radical copolymerization of an acrylate monomer with an ionic group, tetraalkylammonium tetraarylborate, octadecyl acrylate, and a crosslinker, dipropylene glycol diacrylate, in the presence of a radial initiator. Investigation of the swelling behavior for the mixtures of water or aqueous salts reveals that the gel shows similar swelling behavior to those for pure organic solvents. On the other hand, the swelling degree in THF‐water mixture is lower than that of pure THF, because THF and water are miscible to each other, and the presence of a small amount of water in THF reduces the compatibility of the gel and THF. The salting‐out effect can separate the THF‐water mixture to form a biphasic system and recover the high swelling ability of the gel. The swelling behavior in the mixture of water‐organic solvents systems provides a new insight for designing VOC and oil absorbents in various environmental conditions, especially in hydrosphere such as seas and lakes.

Evidence for a high pK a of an aspartic acid residue in the active site of CALB by a fully atomistic multiscale approach

Candida antarctica Lipase B (CALB) is a paradigm for the family of lipases. At pH 7, the optimal pH for catalysis, the protonation state of an aspartic acid of the active site (Asp134) could not be conclusively assigned. In fact, the pK a estimate provided by a widely used computational tool, namely PropKa, that predicts pKa values of ionizable groups in proteins based on the crystallographic structure, is only slightly above 7 (pKa = 7.25). This, along with the lack of an experimental evaluation, makes the assignment of its protonation state at neutral pH challenging. Here, we calculate the pK a of Asp134 by means of a fully atomistic multiscale computational approach based on classical molecular dynamics (MD) simulation and the perturbed matrix method (PMM), namely the MD-PMM approach. MD-PMM is able to take into account the dynamics of the system and, at the same time, to treat the deprotonation step at the quantum level. The calculations provide a pK a value of 8.9 ± 1.1, hence suggesting that Asp134 in CALB should be protonated at neutral, and even at slightly basic, pH. Communicated by Ramaswamy H. Sarma

An imidazole modified lipid confers enhanced mRNA-LNP stability and strong immunization properties in mice and non-human primates

The mRNA vaccine technology has promising applications to fight infectious diseases as demonstrated by the licensing of two mRNA-based vaccines, Comirnaty® (Pfizer/BioNtech) and Spikevax® (Moderna), in the context of the Covid-19 crisis. Safe and effective delivery systems are essential to the performance of these vaccines and lipid nanoparticles (LNPs) able to entrap, protect and deliver the mRNA in vivo are considered by many as the current “best in class”. Nevertheless, current mRNA/LNP vaccine technology has still some limitations, one of them being thermostability, as evidenced by the ultracold distribution chain required for the licensed vaccines. We found that the thermostability of mRNA/LNP, could be improved by a novel imidazole modified lipid, DOG-IM4, in combination with standard helper lipids. DOG-IM4 comprises an ionizable head group consisting of imidazole, a dioleoyl lipid tail and a short flexible polyoxyethylene spacer between the head and tail. Here we describe the synthesis of DOG-IM4 and show that DOG-IM4 LNPs confer strong immunization properties to influenza HA mRNA in mice and macaques and a remarkable stability to the encapsulated mRNA when stored liquid in phosphate buffered saline at 4 °C. We speculate the increased stability to result from some specific attributes of the lipid's imidazole head group.

BIOREMEDIATION POTENTIALS OF EPS: A MINI REVIEW.

EPSs are complex biomolecules composed of proteins, polysaccharides, lipids, and their derivatives. Microorganisms continuously secrete EPS throughout their development and metabolism. The EPS derived from various microbial aggregates have been found to have diverse composition. They are important for microbial cell aggregation, biolm formation, immunomodulation, and are also commercially utilized as food industry gelling agents, heavy metal contaminant sequestration, and other processes (Chug et al., 2021). The ionizable functional groups of EPS, including carboxyl, amine, and hydroxyl, aid in the sequestration of metal ions. Previous research has found a link between microbes' ability to eliminate metals and their synthesis of EPS. EPSs produced by microbes are non-toxic, biocompatible, and biodegradable polymers with several uses in various sectors (Siddharth et al., 2021). Bioremediation by bacterial EPSs can be a cost-effective, sustainable, and simple alternative which is also ecologically viable.

Integrated Quantum Mechanical and Machine Learning Methods Enable Scalable and General pKa Prediction for Pharmacokinetic Modeling

We present the development of the BIOiSIM™ pKa model for predicting aqueous molecular ionization. Assessment and optimization of drug pKa occurs early in drug discovery; thus, models for high‐throughput pKa prediction must balance computational cost, scalability, accuracy, and applicability to diverse chemical structures. Key to our pKa prediction model is a set of low computational cost, quantum mechanical charge descriptors that incorporate not only ionizable group charges, but the additional atoms and bonds likely to modulate pKa. The finalized machine learning models produced good accuracy on the test holdout set (R2 = 0.9, mean absolute error = 0.6−0.7, root mean square error = 1.0) and show good generalizability predicting the most acidic and basic ionization centers of the SAMPL6 external benchmark validation set (mean absolute error = 0.8, root mean square error = 1.0). Performance of the model is comparable to commercial pKa predictors but is trained on less data and exhibits higher scalability needed for pharmacokinetic modeling.

Novel benzofurane carbonyl analogs of donepezil as acetylcholinesterase inhibitors

Donepezil is the most prescribed drug for mild to moderate Alzheimer's Disease. There is not any alternative drug with this potency yet. New scaffolds bearing benzofurans and amines are being tested for good potency on acetylcholinesterase enzyme to mimic donepezil. In this study, we synthesized 22 novel compounds (2a-b, 3a-t) namely benzofuroyl-phenylpiperazines with 3 step reaction having one microwave green synthesis step at first. Compounds were tested with a modified Ellmann method on cholinesterases. Molecular modeling studies were performed on human acetylcholinesterase X-ray crystal structure complexed with donepezil (4EY7) using Maestro Schrödinger. The most active compounds were subjected to a β-amyloid disaggregation assay. All tested compounds showed good activity (except 3n-p bearing Cl on benzofurane) on acetylcholinesterase (0.98–54 µM) and most of the compounds showed a one-digit IC50, where donepezil was 0.12 µM. The most active compounds according to IC50 values were 3t: 0.98 µM, 3s:1.07 µM, 2b:1.08 µM and 2a: 1.14 µM. Besides, compounds did not show significant activity on butyrylcholinesterase at 100 µM. Molecular modeling studies of compounds showed a good consistency (rmsd=0.45) with the binding mode and interactions of donepezil. 2b, 3 s and 3t exhibited good disaggregation potential on 1–40 β-amyloid. Compound 3t disaggregated more than standard drug rifampicin. Cytotoxicity test results on HEK293 (at 50 µM), showed lower cytotoxicity (except for 3j-k) compared to cisplatin (46% viability). Promisingly, the most active compounds on AChE, 2a-b and 3q-t, showed the lowest cytotoxicity (64–74% viability). Consequently, we have developed potent inhibitors of AChE with close activity to donepezil. For enzyme activity; the presence of methoxy on the aromatic site, ionizable nitrogen group and a carbonyl group on/nearly to main ring (benzofurane) asserted essentially to develop more potent compounds that are equivalent to donepezil.

The Ionic Composition and Chemistry of Nanopore-Confined Solutions.

There is increasing interest in understanding the properties of solutions confined within nanotubes and synthetic or biological nanopores. How the ionic content of a nanopore-confined solution differs from that of a contacting bulk salt solution is of particular importance, for example, to water desalinization, industrial electrolysis, and all living systems. This paper explores ionic content, ionic interactions, and ion-transport properties of solutions confined within the 10 nm diameter pores of a synthetic polymer membrane. The membrane has a fixed negative pore-wall and surface charge due to ionizable carbonate groups. As a result, under some conditions, the nanopore-confined solution contains only cations and no anions or salt present in a contacting solution, ideal cation permselectivity. This anion- and salt-rejecting ability varies greatly with the cation of the salt, a result that is in contradiction to the prevailing model for permselectivity in nanopores. The extant model fails because it does not account for specific chemical interactions between the cation and the carbonate groups. The nature of these ion-selective interactions is discussed here.

Direct Affinity Purification of Long-Acting PASylated Proteins with Therapeutic Potential Using L-Prolinamide for Mild Elution.

Both insufficient plasma half‐life (circulation for only few hours or less) and laborious downstream purification can be bottleneck for biological drug development. We report a novel strategy for the efficient and gentle affinity purification of pharmacologically relevant proteins modified by PASylation for prolonged action in vivo. We previously described antibodies specific for Pro/Ala‐rich sequences (PAS) covering a range of binding characteristics. Our present approach relies on a chromatography matrix functionalized with a low‐affinity PAS‐specific antibody Fab fragment for specific adsorption of the PASylated protein from a macromolecular mixture. With the complete absence of hydrophobic/aromatic or ionic groups in the PAS sequence epitope, binding is mediated by Van der Waals contacts and distinct hydrogen bonds only. Surprisingly, selective competitive elution is achieved by application of the highly soluble and biologically inactive imino acid derivative L‐prolinamide. Based on the specific but strongly dynamic biomolecular interaction, our procedure allows the direct one‐step purification of PASylated proteins from a cell extract or culture supernatant while avoiding harsh elution conditions as they are often needed for conventional affinity chromatography.

Direkte Affinitätsreinigung lang wirksamer PASylierter Proteine mit therapeutischem Anwendungspotential unter Nutzung von L‐Prolinamid zur milden Elution

AbstractSowohl unzureichende Plasma‐Halbwertszeit (Zirkulation für nur wenige Stunden oder kürzer) als auch ein aufwendiger Reinigungsprozeß können Flaschenhals sein für die biologische Wirkstoffentwicklung. Wir berichten über eine neuartige Strategie zur effizienten und schonenden Afinitätsreinigung pharmakologisch relevanter Proteine, die durch PASylierung hinsichtlich verlängerter Aktivität in vivo modifiziert wurden. Zuvor hatten wir Antikörper mit Spezifität für Pro/Ala‐reiche Sequenzen (PAS) beschrieben, die ein Spektrum an Bindungseigenschaften abdecken. Unser Ansatz hier beruht auf einer Chromatographiematrix, die mit einem niedrigaffinen PAS‐spezifischen Fab‐Fragment zum Zweck der spezifischen Adsorption des PASylierten Proteins aus einer makromolekularen Mischung funktionalisiert ist. Aufgrund vollständiger Abwesenheit hydrophober/aromatischer oder ionischer Gruppen in dem PAS‐Sequenzepitop wird die Bindung allein durch Van‐der‐Waals‐Kontakte und charakteristische Wasserstoffbrückenbindungen vermittelt. Überraschenderweise kann die selektive kompetitive Elution durch Anwendung des hochlöslichen und biologisch inaktiven Iminosäurederivats L‐Prolinamid erreicht werden. Basierend auf der spezifischen, aber hochdynamischen biomolekularen Wechselwirkung gestattet unser Verfahren die direkte Einschrittreinigung PASylierter Proteine aus einem Zellextrakt oder Kulturüberstand, wobei grobe Elutionsbedingungen, wie sie häufig für die konventionelle Affinitätschromatographie erforderlich sind, vermieden werden.

One-pot preparation of amphoteric cellulose polymers for simultaneous recovery of ammonium and dihydrogen phosphate from wastewater and reutilizing as slow-release fertilizer

In this paper, a simple approach was developed to prepare amphoteric cellulose adsorbent (EAC) through etherification of cellulose with glycidyl trimethyl ammonium chloride (ETA) and glycidylsulfonoic acid sodium salt (SEP) in a one-pot reaction system. The effect of the molar ratio of cellulose to ETA and SEP on the contents of sulfur and nitrogen elements in the EAC was evaluated with the aim of deriving the adsorbents with amounts of ionic functional groups. The EAC was examined for adsorption to NH4+ and H2PO4- ions. Meanwhile, the effect of adsorption parameters, including dosage of EAC, pH value of solution, contact time and ionic strength, on its adsorption capacity was also analyzed. The EAC displayed excellent affinity to the targeted ions, with an adsorption capacity of 40.38 mg/g for NH4+ and 30.42 mg/g for H2PO4-. The adsorption of EAC for NH4+ and H2PO4- reached equilibrium within 30 min and was fitted by second-order and Langmuir models well. More importantly, the EAC after adsorption could be recovered and recycled as a slow-release fertilizer, which could release approximately 95.5% of NH4+ and 92.5% of H2PO4− within 30 days. The results demonstrated that the EAC after adsorption would be reutilized as a slow-release fertilizer, which would give highlights on cost-effective and eco-friendly development in agriculture.

Effect of Ethanol and Urea as Solvent Additives on PSS-PDADMA Polyelectrolyte Complexation.

The effect of urea and ethanol additives on aqueous solutions of poly(styrenesulfonate) (PSS), poly(diallyldimethylammonium) (PDADMA), and their complexation interactions are examined here via molecular dynamics simulations, interconnected laser Doppler velocimetry, and quartz crystal microbalance with dissipation. It is found that urea and ethanol have significant, yet opposite influences on PSS and PDADMA solvation and interactions. Notably, ethanol is systematically depleted from solvating the charge groups but condenses at the hydrophobic backbone of PSS. As a consequence of the poorer solvation environment for the ionic groups, ethanol significantly increases the extent of counterion condensation. On the other hand, urea readily solvates both polyelectrolytes and replaces water in solvation. For PSS, urea causes disruption of the hydrogen bonding of the PSS headgroup with water. In PSS–PDADMA complexation, these differences influence changes in the binding configurations relative to the case of pure water. Specifically, added ethanol leads to loosening of the complex caused by the enhancement of counterion condensation; added urea pushes polyelectrolyte chains further apart because of the formation of a persistent solvation shell. In total, we find that the effects of urea and ethanol rise from changes in the microscopic-level solvation environment and conformation resulting from solvating water being replaced by the additive. The differences cannot be explained purely via considering relative permittivity and continuum level electrostatic screening. Taken together, the findings could bear significance in tuning polyelectrolyte materials’ mechanical and swelling characteristics via solution additives.

Impact of Charge Regulation on Self-Assembly of Zwitterionic Nanoparticles.

Zwitterionic modification of colloids with weak acids and bases represents a promising strategy in creating functional materials with tunable properties and modeling the self-organization of charged proteins. However, accurate incorporation of the dynamic dissociation or association of ionization groups known as charge regulation (CR) is often intractable in theoretical and computational investigations since charge redistribution and configuration need to be evolved self-consistently. Using hybrid MonteCarlo and molecular dynamics simulations, we demonstrate that a dilute suspension of overall charge-neutral zwitterionic Janus nanoparticles shows a conformational transition from an open assembly of string or bundle to compact cluster along with the variation in pH. The behavior under CR is qualitatively different from the commonly employed constant charge condition where the transition is absent. The CR-induced clustering is due to the inhomogeneous and fluctuating charges localized near the equatorial boundary of the Janus particle. These features are enhanced particularly at low salt concentration and high electrostatic coupling strength. Our results indicate the critical role of charge regulation in the spatial self-organization of zwitterionic nanoparticles.

A BODIPY-Based Probe Enables Fluorogenicity via Thiol-Dependent Modulation of Fluorophore Aggregation.

Given the popular usage of BODIPY fluorophores in biological research, their propensity to aggregate in aqueous solution and impact their spectroscopic properties arguably warrants more attention. The probe under study herein serves as a case in point. A para-maleimide-substituted meso-phenyl BODIPY (p-MB) had previously been characterized in organic media, where its inherently high fluorescence ruled out its fluorogenic potential. Here, we have found that in aqueous solution, p-MB behaves differently, exhibiting a much-reduced fluorescence as a result of aggregation-caused quenching (ACQ). Additionally, p-MB is capable of responding to complementarily reactive substrates, including thiols and TCEP, to generate a substantial turn-on signal. The fluorescence restoration is largest when it reacts with those containing adjacent ionizable groups. By being part of a polar conjugate, p-MB assumes a disaggregated form, circumventing ACQ and unleashing up to ~1000-fold fluorescence enhancement through apparent disaggregation-induced emission (DIE). While our results support DIE as the turn-on mechanism, we found that the reactivity of the probe is much lower when it is given time to form stable aggregates. Therefore, contrary to the conventional depiction that a DIE probe works by dispersing from preformed aggregates to react with the target, our results suggest that it functions via a target-mediated inhibition of probe aggregation. Altogether, our work highlights the aggregation issue often faced by BODIPY-based probes and demonstrates how that can be exploited for turn-on sensing application. Furthermore, it reconstructs a different pathway for the DIE mechanism.

Structure-Transport Properties Governing the Interplay in Humidity-Dependent Mixed Ionic and Electronic Conduction of Conjugated Polyelectrolytes.

Polymeric mixed ionic-electronic conductors (MIECs) are of broad interest in the field of energy storage and conversion, optoelectronics, and bioelectronics. A class of polymeric MIECs are conjugated polyelectrolytes (CPEs), which possess a π-conjugated backbone imparting electronic transport characteristics along with side chains composed of a pendant ionic group to allow for ionic transport. Here, our study focuses on the humidity-dependent structure-transport properties of poly[3-(potassium-n-alkanoate) thiophene-2,5-diyl] (P3KnT) CPEs with varied side-chain lengths of n = 4-7. UV-vis spectroscopy along with electronic paramagnetic resonance (EPR) spectroscopy reveals that the infiltration of water leads to a hydrated, self-doped state that allows for electronic transport. The resulting humidity-dependent ionic conductivity (σi) of the thin films shows a monotonic increase with relative humidity (RH) while electronic conductivity (σe) follows a non-monotonic profile. The values of σe continue to rise with increasing RH reaching a local maximum after which σe begins to decrease. P3KnTs with higher n values demonstrate greater resiliency to increasing RH before suffering a decrease in σe. This drop in σe is attributed to two factors. First, disruption of the locally ordered π-stacked domains observed through in situ humidity-dependent grazing incidence wide-angle X-ray scattering (GIWAXS) experiments can account for some of the decrease in σe. A second and more dominant factor is attributed to the swelling of the amorphous domains where electronic transport pathways connecting ordered domains are impeded. P3K7T is most resilient to swelling (based on ellipsometry and water uptake measurements) where sufficient hydration allows for high σi (1.0 × 10-1 S/cm at 95% RH) while not substantially disrupting σe (1.7 × 10-2 S/cm at 85% RH and 8.0 × 10-3 S/cm at 95% RH). Overall, our study highlights the complexity of balancing electronic and ionic transport in hydrated CPEs.

Comb-like polyelectrolytes – New surfactants with controlled solubilization capacity

Cationic surface-active monomers with 11-acryloyloxyundecyl tail in quaternary ammonium group and the corresponding comb-like polyelectrolytes are investigated. The sources of quaternary ammonium were aliphatic amines (trimethylamine and triethylamine) or aromatic and aliphatic cyclic amines (N-methylpiperidine, N-methylmorpholine, pyridine, quinoline). The monomer to polymer transformation increases the solubilization capacity of surfactant in one order of magnitude. The comb-like polyelectrolytes are capable to effective solubilization of hydrophobic probe over the wide concentration range including extremely low concentrations of the polymer. There aren’t any precipitations of comb-like polyelectrolytes with temperature decrease unlike of many ionic low-molecular weight surfactants. Solubilization capacity of the hydrophobic probe by comb-like polyelectrolyte is slightly influenced by the molecular weight of the polymer and is determined by the nature of the ionic group of comb-like polyelectrolyte and counterion.

Chemically Stable Guanidinium Covalent Organic Framework for the Efficient Capture of Low-Concentration Iodine at High Temperatures

The capture of radioactive I2 vapor from nuclear waste under industrial operating conditions remains a challenging task, as the practical industrial conditions of high temperature (≥150 °C) and low I2 concentration (∼150 ppmv) are unfavorable for I2 adsorption. We report a novel guanidinium-based covalent organic framework (COF), termed TGDM, which can efficiently capture I2 under industrial operating conditions. At 150 °C and 150 ppmv I2, TGDM exhibits an I2 uptake of ∼30 wt %, which is significantly higher than that of the industrial silver-based adsorbents such as Ag@MOR (17 wt %) currently used in the nuclear fuel reprocessing industry. Characterization and theoretical calculations indicate that among the multiple types of adsorption sites in TGDM, only ionic sites can bond to I2 through strong Coulomb interactions under harsh conditions. The abundant ionic groups of TGDM account for its superior I2 capture performance compared to various benchmark adsorbents. In addition, TGDM exhibits exceptionally high chemical and thermal stabilities that fully meet the requirements of practical radioactive I2 capture (high-temperature, humid, and acidic environment) and differentiate it from other ionic COFs. Furthermore, TGDM has excellent recyclability and low cost, which are unavailable for the current industrial silver-based adsorbents. These advantages make TGDM a promising candidate for capturing I2 vapor during nuclear fuel reprocessing. This strategy of incorporating chemically stable ionic guanidine moieties in COF would stimulate the development of new adsorbents for I2 capture and related applications.