Alkyl Spacer Length Research Articles

Synthesis and evaluation of novel urethane macromonomers for the formulation of fracture tough 3D printable dental materials

3D printing of materials which combine fracture toughness, high modulus and high strength is quite challenging. Most commercially available 3D printing resins contain a mixture of multifunctional (meth)acrylates. The resulting 3D printed materials are therefore brittle and not adapted for the preparation of denture bases. For this reason, this article focuses on toughening by incorporation of triblock copolymers in methacrylate-based materials. In a first step, three urethane dimethacrylates with various alkyl spacer length were synthesized in a one-pot two-step synthesis. Each monomer was combined with 2-phenoxyethyl methacrylate as a monofunctional monomer and a polycaprolactone-polydimethylsiloxane-polycaprolactone triblock copolymer was added as toughener. The formation of nanostructures via self-assembly was proven by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The addition of the triblock copolymer resulted in a strong increase in fracture toughness for all mixtures. The nature of the urethane dimethacrylate had a significant impact on fracture toughness and flexural strength and modulus of the cured materials. Most promising systems were also investigated via dynamic fatigue propagation da/dN measurements, confirming that the toughening also works under dynamic load. By carefully selecting the length of the urethane dimethacrylate spacer and the amount of block copolymer, materials with the desired physical properties could be efficiently formulated. Especially the formulation containing the medium alkyl spacer length (DMA2/PEMA) and 5 wt% BCP1 (block copolymer), exhibits excellent mechanical properties and high fracture toughness.

Antiswelling and robust supramolecular polyurea hydrogels induced by the synergy of hydrogen bond and hydrophobic interaction for constructing durable underwater anti‐oil‐fouling coatings

AbstractHydrogels are attractive materials for constructing underwater antifouling coatings on solid substrates. However, the application of hydrogel coatings usually faces the obstacles of complex preparation process and poor durability. Herein, we present a facile method to prepare durable hydrogel coatings on metal foils based on rationally designed supramolecular polyurea (PU) hydrogels. PU hydrogels are designed to be cross‐linked with hydrogen bonds (H‐bonds) and hydrophobic interactions in the hard segment domains by using dihydrazides with different alkyl spacer lengths ((CH2)m) as chain extender. The synergy of H‐bond and hydrophobic interaction can stabilize H‐bonds in water, as confirmed by Raman spectroscopy. As a result, PU hydrogels exhibit antiswelling capacity and robustness in both deionized water and seawater. Subsequently, PU hydrogel coatings on Cu/Al foils are prepared by convenient brush coating and subsequent swelling. The resulting hydrogel coatings exhibit excellent underwater anti‐oil‐adhesion and self‐cleaning property, and are durable enough to withstand various static and dynamic damaging tests. The good durability of PU hydrogel coatings should be ascribed to the robust adhesion interface and excellent antiswelling capacity of PU hydrogels. The combination of facile preparation and good durability makes PU hydrogel coatings promising candidates for reliable underwater antifouling.

Carboxyl-Alkyl Functionalized Conjugated Polyelectrolytes for High Performance Organic Electrochemical Transistors.

Contemporary design principles for organic mixed ionic electronic conductors (OMIECs) are mostly based on the ethylene glycol moiety, which may not be representative of the OMIEC class as a whole. Furthermore, glycolated polymers can be difficult to synthesize and process effectively. As an emerging alternative, we present a series of polythiophenes functionalized with a hybrid carboxyl-alkyl side chain. By variation of the alkyl spacer length, a comprehensive evaluation of both the impact of carboxylic acid functionalization and alkyl spacer length was conducted. COOH-functionalization endows the polymer with preferential intrinsic low-swelling behavior and water processability to yield solvent-resistant conjugated polyelectrolytes while retaining substantial electroactivity in aqueous environments. Advanced in situ techniques, including time-resolved spectroelectrochemistry and Raman spectroscopy, are used to interrogate the materials' microstructure, ionic-electronic coupling, and operational stability in devices. To compare these materials' performance to state-of-the-art technology for the design of OMIECs, we benchmarked the materials and demonstrated significant application potential in both planar and interdigitated organic electrochemical transistors (OECTs). The polythiophene bearing carboxyl-butyl side chains exhibits greater electrochemical performance and faster doping kinetics within the polymer series, with a record-high OECT performance among conjugated polyelectrolytes ([μC*]pOECT = 107 ± 4 F cm-1 V-1 s-1). The results provide an enhanced understanding of structure-property relationships for conjugated polyelectrolytes operating in aqueous media and expand the materials options for future OMIEC development. Further, this work demonstrates the potential for conjugated polymers bearing alkyl-COOH side chains as a path toward robust OMIEC designs that may facilitate further facile (bio)chemical functionalization for a range of (bio)sensing applications.

Molecular Tailoring to Achieve Long‐Term Plasticity in Organic Synaptic Transistors for Neuromorphic Computing

Organic synaptic transistors (OSTs) using intrinsic polymer semiconductors are demonstrated to be suitable for neuromorphic bioelectronics. However, diketopyrrolopyrrole (DPP)‐based copolymers are not applicable to neuromorphic computing systems because the DPP polymer film has demonstrated only short‐term plasticity with short retention (<50 ms) in synaptic devices because of their intrinsic difficulty of electrochemical doping. To expand their applications toward neuromorphic computing that requires long‐term plasticity, artificial synapses with extended retention time should be developed. Herein, molecular tailoring approach to extend the retention time in the ion‐gel‐gated OSTs that use DPP is suggested. The molecular structure is controlled by changing alkyl spacer lengths of side chains. As a result, the doping process is more favorable in DPP with long alkyl spacer, which is confirmed by high doping concentration and slow dedoping rate. Therefore, dedoping of ions is more suppressed in DPP with long alkyl side chain that exhibits extended retention time (≈800 s) of the OSTs. These optimized DPP‐based OSTs obtain high pattern recognition accuracy of ≈96.0% in simulations of an artificial neural network. Molecular tailoring strategies provide a guideline to overcome the intrinsic problem of short synaptic retention time of the OSTs for use in neuromorphic computing.

Organic nanoparticles with tunable AIE derived from amino acids appended naphthalenediimide based amphiphiles

Fluorescent organic nanoparticles (FONPs) are unique cooperative manifestations of supramolecular self-aggregates and luminescent nanoparticles. In this work, we developed naphthalenediimide (NDI) based amphiphiles (NDI-1-9) having amino acids substitution from L-alanine to L-phenyl alanine to 3-(2-naphthyl)-L-alanine in absence and presence of alkyl spacer (C-6, C-11). Formation of self-aggregated spherical organic nanoparticles of ∼50 nm took place at and above 50 vol% water or methyl cyclohexane (MCH) in different binary solvent systems (DMSO/DMF-water, CHCl3-MCH) via J-aggregation. In case of NDI-1-3 (amino acids are directly connected to the NDI) self-assembled FONPs (MCH in CHCl3) exhibited aggregation-induced emission (AIE) through excimer formation. Red shift in the emission maxima were observed from 484 nm to 495 nm, and 590 nm, respectively with increasing π electron cloud at substituted donor from NDI-1 to NDI-3. Alongside, in case of aromatic amino acids substitution, FONPs of 6-amino caproic acid spacer containing NDI derivatives (NDI-5 and NDI-6) showed AIE at 505 nm and 545 nm (water in DMF/DMSO). Corresponding 11-amino undecanoic acid containing analogues (NDI-8 and NDI-9) showed AIE at 480 nm and 585 nm in CHCl3-MCH and DMF/DMSO-water. The multi colour emission from blue-green to yellow-orange with enrichment of π-electron cloud density in the side chain substitution of NDI was observed possibly due to the facilitated electron transfer at a lesser energy to the electron deficient NDI core that resulted in red shifted emission maxima. This was further clarified by regulating the availability of π-electrons of phenyl ring of NDI-2 by including electron withdrawing –NO2 and donating -OMe groups at the molecular backbone (NDI-2a and NDI-2b) that showed blue shifted (475 nm) and red shifted (570 nm) emission maxima with respect to NDI-2 (495 nm). However, increase in alkyl spacer length between side chain substitution and NDI core yielded relatively lower quantum yield presumably due to the impeded electron transfer.

Design, synthesis and performance control of dendritic fluorescent liquid crystal polymers with aggregation-induced emission properties

A series of dendritic fluorescent liquid crystal polymers, in which the tetraphenylethylene was linked to the styrene main-chain via flexible spacer with different lengths: poly{3,4,5-tri{[2-(4-oxytetraphenylethylene)-alkoxy]styrene} (denoted as 3P-n, n stands for the length of alkyl spacer and n = 2, 4, 6, 8, 10) were rationally designed and synthesized. The self-assembly behaviors and photophysical properties of 3P-n were investigated in detail by a combination of techniques including differential scanning calorimetry (DSC), polarizing optical microscopy (POM), small-angle X-ray scattering (SAXS), UV–vis absorption spectra (UV–vis spectra) and photoluminescence spectra (PL spectra). Because of the “space volume effect” of side groups and the aggregation-induced emission characteristics of tetraphenylethylene molecule, all of 3P-n are liquid crystal materials with excellent solid-state fluorescence emission performance. Moreover, the self-assembly behaviors and solid-state fluorescence emission efficiency of 3P-n could be effectively regulated by adjusting the flexible spacer length. On one hand, 3P-n could self-assemble into stable columnar nematic phase before decomposition when the flexible spacer was shorter (n = 2, 4, 6, 8). And when the flexible spacer increased to 10, 3P-10 was isotropic at low temperature and formed hexagonal columnar phase at high temperatures, showing typical phase reentrant properties. And the other, the flexible spacer length also made a significant influence on the solid-state fluorescence emission capacity of 3P-n. The solid fluorescence quantum yield of 3P-n first increased with the growth of flexible spacer length (n < 6), and then the solid fluorescence quantum yield of 3P-n would remain unchanged when the flexible spacer increased to a certain length (n≥6).

Asymmetric non-fullerene acceptors enable high photovoltaic performanceviathe synergistic effect of carbazole-terminated alkyl spacer and halogen substitution

A novel design approach of asymmetric NFAviasynergetic alkyl spacer length and halogen substitution enables high photovoltaic performance.

Towards high alkaline stability and fuel cell performance in anion exchange membranes via backbone−cation alkylene spacer tuning for quaternized poly(biphenylene alkylene)s

A major challenge in anion exchange membrane (AEM) fuel cells is the development of high-performed AEMs that can simultaneously meet the criteria of alkaline stable, swelling resistant, and ion conductive. Pentyltrimethylammonium-tethered poly(arylene alkylene)s are emerging as one of the most promising candidates in AEM community, however, they also suffer from conductivity−water uptake trade-offs and improvement-needed alkaline stability. Herein, a series of poly(biphenylene alkylene)-based membranes, PBPA-n-QAs (n = 4, 5, 6), with different alkylene spacer length are synthesized by hydroxyalkylation polymerization and the subsequent amination. The membranes are found to have an improved phase separation as the number of carbon atoms of the alkylene spacers increased from 4 to 6. The ordered morphology and continuous hydrophilic channels make the PBPA-6-QA membrane with outstanding properties including suppressed water uptake, high ion conductivity, and improved alkaline stability. Specifically, the PBPA-6-QA membrane yields the highest hydroxide conductivity (180 mS cm−1 at 80 °C), which is considerably higher than that of PBPA-5-QA and PBPA-4-QA. Furthermore, a single cell using PBPA-6-QA shows a peak power density of 0.97 W cm−2 and can operates stably at a constant current density of 0.2 A cm−2 for 90 h without membrane degradation.

Effect of Molecular Structure of Photoswitchable Surfactant on Light-Responsive Shape Transition of Block Copolymer Particles

Photoactive shape-changing particles offer a promising platform for smart materials with tunable properties at high spatiotemporal resolutions. Herein, a series of spiropyran-based surfactants with different alkyl spacer lengths are developed to achieve photoactive, shape-changing particles through confined self-assembly of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) within an evaporative emulsion. The length of the alkyl chain spacer between the spiropyran headgroup and ionic chain-end is modulated from hexyl to ethyl decanoate to provide surfactants with tunable amphiphilicity. Under UV light, the hydrophilic ring-opened merocyanine surfactants produce onion-like microspheres with a P4VP surface. Conversely, by exposure to visible light, the ring-closure reaction of the spiropyran moieties shifts their hydrophobicity and yields striped ellipsoids with axially stacked PS and P4VP blocks. This sphere-to-ellipsoid transition is observed only for surfactants that contain spacers longer than or equal to octyl. The effects of photoswitchable surfactants on their interfacial properties and corresponding morphological evolution of the particles are investigated to elucidate the mechanism of the shape transition of the photoactive particles.

Crystal Structures of Lignocellulosic Furfuryl Biobased Polydiacetylenes with Hydrogen-Bond Networks: Influencing the Direction of Solid-State Polymerization through Modification of the Spacer Length.

We present the topochemical polymerization of two lignocellulosic biobased diacetylenes (DAs) that only differ by an alkyl spacer length of 1 methylene (n = 1) or 3 methylene units (n = 3) between the diyne and carbamate functionalities. Their crystalline molecular organizations have the distinctive feature of being suitable for polymerization in two potential directions, either parallel or skewed to the hydrogen-bonded (HB) network. However, single-crystal structures of the final polydiacetylenes (PDAs) demonstrate that the resulting orientation of the conjugated backbones is different for these two derivatives, which lead to HB supramolecular polymer networks (2D nanosheets) for n = 1 and to independent linear PDA chains with intramolecular HBs for n = 3. Thus, spacer length modification can be considered a new strategy to influence the molecular orientation of conjugated polymer chains, which is crucial for developing the next generation of materials with optimal mechanical and optoelectronic properties. Calculations were performed on model oligodiacetylenes to evaluate the cooperativity effect of HBs in the different crystalline supramolecular packing motifs and the energy profile related to the torsion of the conjugated backbone of a PDA chain (i.e., its ability to adopt planar or helical conformations).

Synthesis of Heterocyclic Pyridine-Based Chalcones with Dimeric Structure

Three new heterocyclic chalcones containing pyridine moiety were synthesized and their chemical structures were determined via IR, 1H NMR and 13C NMR spectroscopy. General name of these compounds are α,ω-bis{3-(pyridin-3-yl)-1-(phenyl-4-oxy)prop-2-en-1-one}alkanes. The chalcones are dimers having a symmetrical structure and they can be differed by the alkyl spacer length (CnH2n, where n = 8, 10 or 12). Differential scanning calorimetry (DSC) technique was employed to study their phase transition behaviors. DSC thermograms displayed direct isotropization and recrystallization during heating and cooling processes, respectively. The crystal phase turned into isotropic phase without exhibiting any mesophase. Influence of structure-liquid crystalline property relationships of the symmetrical dimers was examined in order to explain the reasons for the non-liquid crystalline properties in the current chalcones.

Structural analysis of bis(pyridyl)diimines: Factors affecting the molecular geometry and supramolecular packing

Systematic analysis of structural features of a series of bis(pyridyl)diimines is done to have an understanding on the effect of different types of interactions in modulating the molecular geometry and final packing of the molecules in the solid state. Supramolecular synthons that may result from weak interactions such as CH···N and aromatic interactions are difficult to predict and hence analyzing homologous series of compounds, which can organize only by weak interactions will lead to generating data sets on various possibilities of synthons. In the series of bis(pyridyl)diimines, small variation in the molecular features such as position of nitrogen on pyridyl ring, presence of hydrogen or methyl group on imine carbon and changing the alkyl spacer length is being related to the observed changes in the occurrence of non-covalent interactions and finally in the crystal packing in the solid state. Cooperative effect of intermolecular interactions and steric factors decide the final structural arrangement, which is being inferred by observing the solid state arrangement of the compounds. Crystallization induced emission of the bis(pyridyl)diimines is also studied and correlated with their structural features and the overall supramolecular architecture.

Effects of the Polarity and Bulkiness of End-Functionalized Side Chains on the Charge Transport of Dicyanovinyl-End-Capped Diketopyrrolopyrrole-Based n-Type Small Molecules.

When designing organic semiconductors, side-chain engineering is as important as modifying the conjugated backbone, which has a significant impact on molecular ordering, morphology, and thus electronic device performance. We have developed three dicyanovinyl-end-capped donor-acceptor diketopyrrolopyrrole-based n-type small molecules (C2C9CN, SiC4CN, and EH4PCN) bearing an identical length of alkyl spacer yet different end-functionalized side chains (i.e., alkyl-, siloxane-, and phosphonate-end pendants). The effects of the end-functionalized side chains on the intrinsic molecular properties, microstructure, and charge transport of the small-molecule series were investigated. In comparison with the alkyl-end side chains, incorporating siloxane-end side chains into the backbone facilitates 2D edge-on oriented high intergrain connectivity/crystallinity and compatibility with the substrate surface, whereas the phosphonate-end analogues have an adverse effect on the film-forming quality due to high polarity. Thereby, an organic field-effect transistor fabricated by SiC4CN shows the best electron mobility up to 1.59 × 10-1 cm2 V-1 s-1 along with a high current on/off ratio >105. This study contributes to our understanding of the role of the end-functionalized side chains (e.g., the effects of polarity and bulkiness of the end groups) for the development of high-performance semiconductors.

Fullerene-Based Triads with Controlled Alkyl Spacer Length as Photoactive Materials for Single-Component Organic Solar Cells.

Two kinds of dumbbell-shaped acceptor-donor-acceptor (A-D-A)-type triad single-component (SC) photovoltaic molecules based on a benzodithiophene-rhodanine (BDTRh) core and [6,6]-phenyl-C61 butyric acid (PC61BA) termini, BDTRh-C2-PC61BA and BDTRh-C10-PC61BA, were synthesized by modulating the alkyl (C2 and C10) spacer lengths. Both SC photovoltaic structures had similar UV-vis spectra in solution, but BDTRh-C10-PC61BA showed a significantly higher absorption coefficient as a thin film. In films, a more facile intermolecular photo-induced charge transfer was observed for BDTRh-C10-PC61BA in the broad-band transient absorption measurements. BDTRh-C10-PC61BA also exhibited a higher hole mobility (by 25 times) and less bimolecular recombination than BDTRh-C2-PC61BA. By plotting the normalized external quantum efficiency data, a higher charge-transfer state was measured for BDTRh-C10-PC61BA, reducing its voltage loss. A higher power conversion efficiency of ∼2% was obtained for BDTRh-C10-PC61BA, showing higher open-circuit voltage, short-circuit current density, and fill factor than those of BDTRh-C2-PC61BA devices. The different carrier dynamics, voltage loss, and optical and photoelectrical characteristics depending on the spacer length were interpreted in terms of the film morphology. The longer decyl spacer in BDTRh-C10-PC61BA afforded a significantly enhanced intermolecular ordering of the p-type core compared to BDTRh-C2-PC61BA, suggesting that the alkyl spacer length plays a critical role in controlling the intermolecular packing interaction.

Series-Connected Tetracation Partially Cross-Linked Anion Exchange Membranes: Insight towards Consequences of Alkyl Spacer Length

Series-Connected Tetracation Partially Cross-Linked Anion Exchange Membranes: Insight towards Consequences of Alkyl Spacer Length

Weakly acidic carboxy group-grafted β-cyclodextrin-threaded acid-degradable polyrotaxanes for modulating protein interaction and cellular internalization

ABSTRACT To improve the therapeutic potential of β-cyclodextrin (β-CD)-threaded acid-degradable polyrotaxanes (β-CD PRXs) in cholesterol-related metabolic disorders, we investigated the effect of carboxylation of β-CD PRXs on intracellular uptake. In this study, we established a synthetic method for the modification of carboxylalkyl carbamates on β-CD PRXs without degradation and synthesized three series of carboxyalkyl carbamate group-modified β-CD PRXs with different alkyl spacer lengths. The modification of carboxymethyl carbamate (CMC), carboxyethyl carbamate (CEC), and carboxypropyl carbamate (CPC) on the β-CD PRXs slightly reduced the interaction of the PRXs with the lipid layer model compared with the modification of 2-(2-hydroxyethoxy)ethyl carbamate (HEE-PRX), which was used in our previous studies. However, all the carboxylated β-CD PRXs showed a significantly stronger interaction with a protein model compared with HEE-PRX. The carboxylated β-CD PRXs showed significantly high intracellular uptake, through macrophage scavenger receptor A (MSR-A)-mediated endocytosis, in MSR-A-positive RAW 264.7 cells compared with HEE-PRX. Interestingly, the carboxylated β-CD PRXs also showed significantly higher intracellular uptake even in MSR-A-negative cells compared with HEE-PRX. Carboxylated β-CD PRXs are considered to strongly interact with other membrane proteins, resulting in high intracellular uptake. The length of the alkyl spacer affected the intracellular uptake levels of carboxylated PRXs, however, this relationship was varied for different cell types. Furthermore, none of the carboxylated β-CD PRXs exhibited cytotoxicity in the RAW 264.7 and NIH/3T3 cells. Altogether, carboxylation of β-CD PRXs is a promising chemical modification approach for their therapeutic application because carboxylated β-CD PRXs exhibit high cellular internalization efficiency in MSR-A-negative cells and negligible toxicity.

Effect of dicationic ionic liquids on cloud points of tergitol surfactant and the formation of aqueous micellar two-phase systems

A cloud point evaluation was performed for the nonionic surfactant Tergitol 15-S-7 in aqueous solutions of McIlvaine buffer (pH 7.0). Cloud point temperatures of the selected nonionic surfactant were studied in relation to the effect that the addition of dicationic ionic liquids (ILs) had on the systems. The dicationic ILs with different alkyl spacer lengths were derived from 1, n-bis(3-methylimidazolium-1-yl)alkane bromide ([BisAlk(MIM)2][2Br]) — in which Alk = But, Hex, Oct, and Dec. The dicationic ILs with longer alkyl spacer chains (Alk ≥ 6) led to an increase in the Tergitol’s cloud point values, due to their ability to fold their structures in solution, which increase the interactions of ILs with tergitol in the mixed micelles. This increase was even more pronounced when the concentration of the dicationic ILs was increased. Furthermore, the addition of dicationic ILs increased the micelles size; however, the hydrodynamic diameter of mixed micelles did not depend on the length of the ILs’ alkyl spacer chains. The Tergitol/IL systems with lower critical micellar concentration values will result in higher cloud point values, due to the greater colloidal dispersion stability.

A Series of Bisamide-Substituted Diacetylenes Exhibiting a Terminal Alkyl Odd/Even Parity Effect on Mechanoactivated Photopolymerization.

Diacetylene derivatives exhibit solid-state polymerization to polydiacetylene initiated by UV light or γ-ray irradiation. The activation of the photopolymerization relies on the monomer diynes arrangement. Recently, it has been demonstrated that the first mechanoresponsive bisamide substituted diacetylenes (DAs) show dramatic switching from light-inert to light-reactive states at a given pressure. The origin of this unique phenomenon was apparently related to the pressure-sensitive crystalline transition in DAs, but the molecular mechanism remains elusive. To obtain more insight, herein a series of DAs with varying terminal alkyl spacer length is presented, and their molecular structural effect on the intermolecular hydrogen bonding and steric repulsion is examined. In pristine states, even-parity DAs were inactive upon UV irradiation (λ=254 nm) unless external pressure was applied. By contrast, odd-parity DAs were easily polymerized upon UV irradiation without pressure application. However, the pressure-induced crystalline phase transition exhibiting photopolymerization was valid for all DAs regardless of their alkyl spacer length. A systematic investigation revealed that the terminal alkyl spacer length, especially its odd/even parity plays a key role in determining the intrinsic intermolecular hydrogen-bonding nature of DA crystals and the resultant molecular packing. In addition, the relevant thermochromic behavior was also observed from photopolymerized polydiacetylenes.

Strategic engineering of alkyl spacer length for a pH-tolerant lysosome marker and dual organelle localization.

Long-term visualization of lysosomal properties is extremely crucial to evaluate diseases related to their dysfunction. However, many of the reported lysotrackers are less conducive to imaging lysosomes precisely because they suffer from fluorescence quenching and other inherent drawbacks such as pH-sensitivity, polarity insensitivity, water insolubility, slow diffusibility, and poor photostability. To overcome these limitations, we have utilized an alkyl chain length engineering strategy and synthesized a series of lysosome targeting fluorescent derivatives namely NIMCs by attaching a morpholine moiety at the peri position of the 1,8-naphthalimide (NI) ring through varying alkyl spacers between morpholine and 1,8-naphthalimide. The structural and optical properties of the synthesized NIMCs were explored by 1H-NMR, single-crystal X-ray diffraction, UV-Vis, and fluorescence spectroscopy. Afterward, optical spectroscopic measurements were carefully performed to identify a pH-tolerant, polarity sensitive, and highly photostable fluoroprobes for further live-cell imaging applications. NIMC6 displayed excellent pH-tolerant and polarity-sensitive properties. Consequently, all NIMCs were employed in kidney fibroblast cells (BHK-21) to investigate their applicability for lysosome targeting and probing lysosomal micropolarity. Interestingly, a switching of localization from lysosomes to the endoplasmic reticulum (ER) was also achieved by controlling the linker length and this phenomenon was subsequently applied in determining ER micropolarity. Additionally, the selected probe NIMC6 was also employed in BHK-21 cells for 3-D spheroid imaging and in Caenorhabditis elegans (C. elegans) for in vivo imaging, to evaluate its efficacy for imaging animal models.

Monovalent anion selective anion-exchange membranes with imidazolium salt-terminated side-chains: Investigating the effect of hydrophobic alkyl spacer length

Ion-conductive polymers having highly ordered and well-defined phase-separated structures are potential materials for use as monovalent anion-selective membranes (MASMs). In this work, to investigate the effect of hydrophobic spacers, four side-chain-type imidazolium salt-tethered poly(arylene ether sulfone) anion-exchange membranes (AEMs) with different alkyl spacer lengths (–CH2– number: 3, 6, 9, and 12) were fabricated for use in electrodialysis (ED). Our investigations using atomic force microscopy, small angle X-ray scattering and X-ray diffraction demonstrate that the extended alkyl spacers change the nano-phase-separated structures, with an increased ion cluster space ranging from 3.29 nm to 7.76 nm, resulting from increased immiscibility between the additional hydrophobic alkyl spacers and (i) the hydrophobic aromatic backbones and (ii) the hydrophilic ion-conductive groups. In addition, with the extension of the alkyl spacer, chloride (Cl−) ion conductivity at 25 °C decreases from 16.4 mS cm−1 to 11.4 mS cm−1 and water uptake is reduced to 12.8% (20 °C). It is found that the as-prepared AEM with a hexyl alkyl spacer shows the superior perm-selectivity (Cl−/SO42−) of 7.10 (separation efficiency: 70.3%), as compared with three others (3.48, 6.81, and 4.26). This work thus presents an efficient strategy to guide the architectural design of novel MASMs.