Synthesis of stretchable polyetherimides containing multiple alkyl side chains

Two series of diamine monomers, i.e., 4-[3,4,5-tris(n-alkan-1-yloxy)benzyl]-3,5-diaminobenzoate and 2,2′-bis{4-[3,4,5-tris(n-alkan-1-yloxy)benzoate]}-4,4′-biphenyldiamines containing multiple alkyl side chains, were synthesized in which the length of the alkyl side chains was varied from 5 to 18 ethylene units. Polyetherimides (PEIs) were prepared from these two diamines and bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydrides (BisADA) using a one-step method in 1-chloronaphthalene. All the polymers possessed good solubility in chlorinated solvents. The high-molecular weight PEIs could be solution cast into transparent, tough films. The polymers containing the side chains which were at least 16 methylene units could be crystallized. The melting points of the crystals increased as the length of the side chains increased. The glass transition temperatures (T_gs) of the PEIs decreased as the length of the side chains increased due to an internal plasticizing effect of the alkyl side chains. The PEIs containing multiple alkyl side chains showed excellent drawability with much higher elongations but lower tensile strengths and moduli compared with the commercial PEI, Ultem^® 1000. The film's in-plane refractive index parallel to the drawing direction (n_//) increased and its in-plane refractive index perpendicular to the drawing direction (n_⊥) decreased during drawing mainly due to the orientation of main chains in the drawing direction. The film's in-plane birefringence increased with the drawing ratios.     

Alkylated graphene nanosheets for supercapacitor electrodes: High performance and chain length effect

Single electrode materials capable of both electric double-layer and Faradic redox-based pseudo capacitance can be used for fabrication of high performance supercapacitors in an easy way and thus are highly desirable in the energy storage field. This contribution reports a new kind of such materials based on alkylated graphene materials (C_nrGO, n is the carbon number of their alkyl side chains) having different alkyl side chains (n = 4, 8, and 16). These materials were prepared via esterification of KOH-treated GO with the corresponding alkyl bromides in the presence of a phase transfer catalyst. More importantly, water was used as the reaction medium, and thus endowing the preparation method an eco-friend feature. The so-prepared graphene materials displayed chain length-dependent specific surface area and the population of residue CO functionalities, and thus affording vast differences in their supercapacitor behaviors. C₄rGO, the product having butyl side chains, showed the best supercapacitor performance with a capacitance up to 242.2 F g⁻¹ at a scan rate of 100 mV s⁻¹ and a good cycling stability.     

Controlling the morphology of polybutadiene-poly(ethylene oxide) diblock copolymers in bulk and the orientation in thin films by attachment of alkyl side chains

A polybutadiene₁₉-block-poly(ethylene oxide)₉₄ (PB-PEO) has been modified by free-radical additions of 2-ethylhexanethiol, 1-decanethiol, and 1-dodecanethiol separately to the PB block. The block copolymers were characterized by DSC, SAXS, XRD and AFM measurements. Above the melting temperature of PEO, PB-PEO showed hexagonal morphology having PB cylinders in the PEO matrix. The addition of alkyl side chains decreased the volume fraction of PEO and the morphology changed to lamellar for ethylhexyl side chains and to reversed hexagonal morphology with PEO cylinders in the PB/alkyl chain matrix for decyl and dodecyl side chains. Below the melting temperature of PEO, all polymers showed lamellar morphology. In the case of dodecyl side chains, the lamellar morphology oriented perpendicular to the air/film interface and was stable against high temperature annealing.     

Evolution of the local structure and electrochemical properties of spinel LiNixMn2−xO4 (0 ≤ x ≤ 0.5)

A series of Ni substituted spinel LiNi_xMn_2−xO₄ (0 ≤ x ≤ 0.5) have been synthesized to study the evolution of the local structure and their electrochemical properties. X-ray diffraction showed a few Ni cations moved to the 8a sites in heavily substituted LiNi_xMn_2−xO₄ (x ≥ 0.3). X-ray photoelectron spectroscopy confirmed Ni²⁺ cations were partially oxidized to Ni³⁺. The local structures of LiNi_xMn_2−xO₄ were studied by analyzing the and A_1g Raman bands. The most compact [Mn(Ni)O₆] octahedron with the highest bond energy of Mn(Ni)O was found for LiNi_0.2Mn_1.8O₄, which showed a Mn(Ni)O average bond length of 1.790 Å, and a force constant of 2.966 N cm⁻¹. Electrolyte decomposition during the electrochemical charging processes increased with Ni substitution. The discharge capacities at the 4.1 and 4.7 V plateaus obeyed the linear relationships with respect to the Ni substitution with the slopes of −1.9 and +1.9, which were smaller than the theoretical values of −2 and +2, respectively. The smaller slopes could be attributed to the electrochemical hysteresis and the presence of Ni³⁺ in the materials.     

Guest release and solution behavior of a hydrogen-bonding physical micelle during chemoresponsive shell disruption

The guest release and solution behavior during shell disruption of a polymeric nanocapsule are described. Hyperbranched polyethylenimine (PEI, M_n = 10?000) is chemically functionalized with multiple DAD hydrogen-bonding motifs (D and A: hydrogen-bonding donor and acceptor), leading to PEI₂₃₂-(DAD)_x (3) (x = 93 (3a), x = 46 (3b), x = 23 (3c), x = 12 (3d)). Meanwhile, polyethylene oxide (M_n = 2 200) is end-capped with thymine moieties (PEO-ADA) (4). Mixing of the hydrogen-bonding complementary 3 and 4 (DAD/ADA = 1) leads to a physical micelle (3·4) in apolar media, and the resulting micelle can completely and irreversibly transfer the ionic and water-soluble Congo red (CR) into chloroform phase by encapsulation. Experiment proves that the micelle can exist as a pseudo-unimolecular micelle (p-UIM, meaning one PEI in one micelle) or as aggregate, depending on the shell density. As a result, 3b·4 generally exists as a p-UIM while 3d·4 can exist as p-UIM only in a very narrow range of concentrations. The critical aggregation concentration (CAC) is also dependent on the core structure of the micelle, thus when the residual amines in the core of 3b are transformed into amide, the resulting 5b·4 shows a very low CAC. Small chemicals bearing DAD hydrogen-bonding motif can compete to bind with the PEO-ADA shell and destruct the p-UIM, leading to aggregation and precipitation of the p-UIM along with the CRs. Experiment proves that the CR has strong acid-base interaction with the PEI core of the p-UIM, but when the basicity of the PEI core is reduced by amidation, partial CRs can be released into the water phase.     

The structure of a cyanobiphenyl side chain liquid crystalline poly(silylenemethylene)

The structure of a side chain liquid crystalline poly(silylenemethylene) (-(SiCH₃R-CH₂)-: R=O(CH₂)₁₁O-Ph-Ph-CN, Ph=phenyl) (CN-11) has been studied by X-ray diffraction and differential scanning calorimetry (DSC). The DSC results showed that CN-11 has transitions at ∼92 °C (T₂) and ∼147 °C (T₁) during both cooling and immediate heating. A third transition occurred at ∼50 °C (T₃) during heating after annealing at room temperature. The X-ray fiber pattern of the CN-11 annealed at room temperature showed several wide and small angle reflections which were indexed by a monoclinic unit cell with parameters a=16.8 Å, b=7.42 Å, c=43.6 Å and β=102.1° (b: fiber direction), representing a crystal structure with layer thickness of ∼43 Å. Upon heating at T₃, the crystal structure became less ordered (but somewhat more ordered than smectic A (S_A) and smectic C (S_C)). This was followed by S_A (or S_C) phase at T₂, and ultimately an isotropic state (I) at T₁. The observed layer thickness (∼43 Å) is about ∼1.5 times the most extended side chain length, indicating a double-layer structure with tilted or interdigitated side chains. The X-ray fiber pattern had a four-point pattern at d=4.52 Å, suggesting that the side chains in the crystal are likely to be tilted by 56° from the polymer fiber axis.     

A Series of Luminescent Lanthanide–Organic Complexes Constructed from In Situ Generated Dithiobenzoic Acid

Two types of lanthanide thiolato-carboxylate complexes, [Type I: [Yb(dtba) (Hdtba)] _n (1), Type II: [Ln(dtba)_1.5(biim)] _n (Ln = Pr (2a), Nd (2b), Sm (2c), Eu (2d), Gd (2e), Tb (2f), Dy (2g), H₂dtba = 2,2′-dithiodibenzoic acid, bimm = diimidazole)] have been obtained by hydrothermal method and characterized by the single-crystal X-ray diffraction, IR, 2D-COS IR, TG and the luminescence analysis. The H₂dtba ligand came from the in situ S–S function reaction of 2-mercaptobenzoic acid (H₂mba) under the hydrothermal condition. Complex 1 is a 2D bamboo-like sqr-topology layered structure, and the 3D (4, 4, 6)-connected supramolecular frameworks is produced by the hydrogen bonds of O–H···O. Complexes of type II (from 2a to 2g) are isostructural and they are assigned to 1D rope-like chains by introducing the chelating ligand of diimidazole. These 1D rope-like chains are further linked by N–H···O hydrogen bonds into a 3D supramolecular framework with CdSO₄-type topology. Photoluminescence studies reveal that complexes 2b, 2c, 2d, 2f, 2g exhibit strong lanthanide characteristic emission bands in the solid state at room temperature.     

The structures of poly(oxyethylene)s having sulfone groups in the side chains

The structures of (OCH₂CHR) with R=CH₂S(CH₂)₆SO₂(CH₂)_MH (ATP-M; M=5,7,9) or R=CH₂SO₂(CH₂)₆SO₂(CH₂)_MH (ASP-M; M=5,7,9) were studied using X-ray diffraction and differential scanning calorimetry. The X-ray patterns of all ATPs and ASPs studied show a series of ordered reflections in the small angle region and a sharp wide angle reflection at d=∼4.4 Å, characteristic of a smectic phase. The smectic layer thickness corresponds to twice the most extended side chain length and linearly increases as the side chain length increases with a slope of ∼2.3 Å per methylene spacer. This indicates that all ASPs and ATPs studied have a double layer structure with side chains normal to the main chain and probably an all-trans conformation of the side chains. The correlation lengths measured from the wide angle reflections are in the range of 80±10 Å for all the polymers except for ASP-5 (∼40 Å). These values indicate that quasi-long-range order exists in the smectic layers whose structures can be defined as smectic B (S_B). The d-spacing of the wide angle reflection, 4.4 Å, suggests that paraffinic side chain crystallization does not occur and that the smectic mesophase develops through dipole-dipole interactions of sulfone groups in the side chains. During heating, ATP-5 shows recrystallization after the first melting. The structure produced during recrystallization has a similar smectic structure but with more dense packing between side chains than before the first melting. In the case of ASP-9, a smectic to smectic transition was observed at ∼110°C prior to the isotropic temperature at ∼150°C. Both the correlation length (from the wide angle reflection) and the layer thickness decreased from ∼80 to ∼30 Å and from 46 to 40 Å at this transition, respectively, indicating that the order in the smectic layers is lost and the S_B structure has become a less ordered S_A structure at this transition.     

The crystal structure of jennite, Ca9Si6O18(OH)6·8H2O

The crystal structure of jennite is solved and refined in the space group P1?, by using single crystal X-ray diffraction data collected at the Elettra synchrotron radiation facility on a very thin crystal from Fuka, Japan. The triclinic refined unit cell is a=10.576(2) Å, b=7.265(2) Å, c=10.931(3) Å, α=101.30(1), β=96.98(1), γ=109.65(1)°. The structure of jennite is built up by three distinct modules: ribbons of edge-sharing calcium octahedra, silicate chains of wollastonite-type running along b, and additional calcium octahedra on inversion centres. The structural results indicate that the crystal chemical formula of jennite is Ca₉Si₆O₁₈(OH)₆·8H₂O, and that all the hydroxyl groups are bonded to three calcium cations; SiOH groups are not found. The structural disorder observed in jennite is explained on the basis of the OD theory, and a model for the structure of metajennite, the dehydration product of jennite, is proposed.     

Synthesis and gas permeability of ester substituted poly(p-phenylene)s

Polymerizations of various ester substituted 2,5-dichlorobenzoates [substituent: linear alkyl groups (1a-f), branched alkyl groups (1g-l), cyclohexyl groups (1m-o), phenyl groups (1p-r), and oxyethylene units (1s-v)] were investigated with Ni-catalyzed/Zn-mediated system in 1-methyl-2-pyrrolidone (NMP) at 80 °C. Most of monomers bearing linear and branched alkyl groups successfully polymerized to give relatively high-molecular-weight polymers (M_n = 10,000-20,800). However, the molecular weight of the polymer having eicocyl groups was low because of steric hindrance of long alkyl chain. The polymerizations of cyclohexyl 2,5-dichlorobenzoate and phenyl 2,5-dichlorobenzoate produced low-molecular-weight polymers, while the polymerizations of monomers with alkyl cyclohexyl and alkyl phenyl groups proceeded to afford polymers with relatively high-molecular-weights. The polymers possessing oxyethylene units were obtained, but the molecular weights were low when the oxyethylene chains were long. The gas permeability of membranes of poly(p-phenylene)s with alkyl chains increased as increasing the length of alkyl chain. The membranes of poly(p-phenylene)s with phenyl groups and oxyethylene units exhibited high densities and relatively low gas permeability. However, the CO₂/N₂ separation factor of membrane of poly(p-phenylene) having oxyethylene units was as large as 73.6.     

Synthesis and Characterization of Novel Aryl Alkyl Sulfonates Based on Nonylphenol

A series of nonylphenol-substituted alkyl sulfonates (C _x NPAS, x = 8, 10, 12, 14, 16) with two hydrocarbon chains and two different hydrophilic groups has been synthesized from α-olefins and nonylphenol. The respective products have a “pseudo-gemini” surfactant structure. The structures of the C _x NPAS have been characterized by IR, UV, ¹H nuclear magnetic resonance, electrospray ionization mass spectrometry, and elemental analysis. The effects of carbon chain length of the obtained surfactants on properties such as the critical micelle concentrations (CMC) in aqueous solutions, surface tension at the CMC (γ _CMC), and efficiency of adsorption at the water/air interface (pC ₂₀) have been determined. The γ _CMC of the surfactants first decreased and then increased with increasing length of the carbon chain x, and reached a minimum of 29.25 mN/m at x = 10, which is much lower than that of α-olefin sulfonate (AOS) (33.52 mN/m). The CMC decreased and pC ₂₀ increased with increasing x. The introduction of the hydroxyl group is responsible for multiple molecular conformations at the water/air interface and leads to a greater molecular area A _min and smaller Γ_max than those of AOS.     

Hydrothermal Syntheses and Crystal Structures of Three Complexes Constructed with Dipyrido[3,2-a:2′,3′-c]phenazine and 2,4′-Biphenyldicarboxylic Acid

Three new metal complexes, [Pb(dppz)(2,4′-bpdc)] _n ·n(H₂O) (1), [Fe(dppz)(2,4′-bpdc)(H₂O)] _n (2) and [Cu(dppz)(2,4′-bpdc)(H₂O)] _n (3) (2,4′-H₂bpdc = 2,4′-biphenyldicarboxylic acid and dppz = dipyrido[3,2-a:2′,3′-c]phenazine), have been synthesized and characterized by elemental analysis, IR, X-ray single-crystal diffraction and powder X-ray diffraction. The complexes 1, 2 and 3 have 1D chains formed via coordination bonds, and unique three-dimensional or two-dimensional supramolecular structures are further formed due to π–π stacking interactions. The results reveal that the coordination preferences of metal ions play a critical role in the framework construction of these complexes. Meanwhile, the thermogravimetric analysis and photoluminescent property of compounds 1–3 have also been investigated.     

Preparation, characterization and bifunctional electrocatalysis of an inorganic-organic complex with a vanadium-substituted polyoxometalate

An inorganic-organic complex with a vanadium-substituted polyoxometalate 1, formulated as [Cu(phen)₂]₂PVW₁₁O₄₀ was hydrothermally synthesized. Complex 1 crystallizes in the monoclinic P2(1)/c space group with a = 25.9932(12) Å, b = 11.9889(6) Å, c = 23.2672(11) Å, β = 113.6750(10)°, V = 6640.5(6) Å³, R = 0.0312, and Z = 4. Complex 1 is constructed from a Keggin-type anion PVW₁₁O₄₀⁴⁻ coordinated to two [Cu(phen)₂]²⁺ units. One [Cu(phen)₂]²⁺ unit is coordinated to a terminal oxygen and the other [Cu(phen)₂]²⁺ unit is coordinated to a bridging oxygen of the polyoxoanion. Redox activities for both the tungsten and vanadium centers have been observed using cyclic voltammetry performed on 1-bulk modified carbon paste electrode (CPE). It was found that 1 presents good electrocatalytic activities not only for the reduction of IO₃⁻, NO₂⁻, and H₂O₂ but also the oxidation of l-cysteine. Complex 1 also shows intense luminescent properties arising from ligand-to-copper charge transfer and oxygen-to-vanadium charge transfer at room temperature in the solid state.     

Purification,Surface Tensions,and Miscibility Gaps of Alkyldimethyl and Alkyldiethylphosphine Oxides

Alkyldimethyl (C _n DMPO) with chain lengths of n = 8 (octyl), 10 (decyl), 12 (dodecyl), and 14 (tetradecyl) as well as alkyldiethyl (C _n DEPO) phosphine oxides with chain lengths of n = 10, 12, and 14 were synthesized and purified to study how the adsorption properties and the location of the miscibility gap of these surfactants depend on the size of the head group and on the length of the alkyl chain. After surfactant purification, the surface tension isotherms were determined from which the cmc, the minimum surface tension σ_cmc, the maximum surface concentration Γ_max, and the minimum surface area A _min were obtained. As expected, for one homologous series, a decrease in the cmc and an increase in Γ_max was observed with increasing alkyl chain length. For two surfactants of the same alkyl chain length, the cmc values of the C _n DEPO surfactants are approximately two times lower than those of the C _n DMPO surfactants. However, the Γ_max values of C _n DEPO are lower than those of C _n DMPO as two ethyl chains are sterically more demanding than two methyl chains. In addition to the adsorption properties, the location of the miscibility gap as a function of the alkyl chain length and the head group size was studied. Its location depends on the total number of carbon atoms and not primarily on the length of the main alkyl chain. This observation reflects the decreasing water solubility which can be tuned by increasing the length of either the main alkyl chain or of the shorter head group chains.     

Conformations and dynamics of adsorbed protein-like chains

Conformations and dynamics of adsorbed protein-like chains are investigated by using Monte Carlo simulation based on the modified orientation-dependent monomer-monomer interaction (ODI) model. The chain size and shape of adsorbed protein-like chains, such as mean-square end-to-end distance 〈R²〉, mean-square radius of gyration 〈S²〉_xy (or 〈S²〉_z), shape factors , and 〈δ^*〉 are discussed here. At the same time, fraction of adsorbed segment f_a and average orientation of bond 〈P₂(cos θ)〉 are also investigated. The adsorbed protein-like chains trend to be more flat when adsorption interaction energy becomes strong. Different kinds of interactions (such as contact interaction, sheet interaction, spin-spin interaction, helical interaction, and adsorbed interaction) are considered in detail. Dynamics of adsorbed protein-like chains are investigated by calculating their diffusion coefficients, and we find that there exist the relationships of Dxy∼N−γxyand Dz∼N−γz, and the values of γ_xy and γ_z are 4-5 times larger than that of general self-avoiding walk (SAW) chains. These investigations may provide some insights into adsorption of proteins.     

Polymer-metal complexes,based on poly(itaconic acid ester) derivatives,as catalysts for the decomposition of hydrogen peroxide

Poly(methyl itaconates) and poly(heptyl itaconates), modified with ethylene diamine (EN) and tetraethylene pentamine (TETRAEN) side chains, were complexed with cobalt and copper ions, and their efficiencies as catalysts for the decomposition of hydrogen peroxide were assessed. All the polymer complexes studied were found to be active catalysts, but it was observed that the polymers with TETRAEN side chain, when complexed with CoCl₂ and CuCl₂ were less efficient than polymers with EN side chains which were complexed with trans-dichlorobis(ethylenediamine) cobalt(III) chloride, trans-[Co(EN)₂Cl₂]Cl. One feature of interest was that when the alkyl side chain of the poly itaconate was heptyl the rate of decomposition of hydrogen peroxide was faster than when the alkyl group was methyl.     

The crystal structure of poly(2,6-naphthalenebenzobisthiazole)

The crystal structure of poly(2,6-naphthalenebenzobisthiazole) (Naph-2,6-PBT) was studied using X-ray and molecular modeling methods. The X-ray pattern of the annealed Naph-2,6-PBT fiber showed several Bragg reflections as well as streaks along the layer lines indicating that the registry between adjacent chains exists in the crystal with a great deal of axial disorder. Disordered structure in the crystal was fitted into the triclinic unit cell with the unit cell parameters of a=6.78 Å, b=3.46 Å, c=14.61 Å, α=88.0°, β=114.7°, and γ=94.8° with space group. The calculated density, 1.68 g/cm³ was comparable with the observed density, 1.56 g/cm³. The Δc/c (staggering ratio) representing the registry between the adjacent chains in the ac plane was −0.19, which is in good agreement with the energy calculation although another local energy minimum was found at Δc/c=0.31. The disordered structure in Naph-2,6-PBT was probably due to the discrete axial shift between Δc/c=0.31 and −0.19 in the ac plane. The LALS refinement showed that the naphthalene group was rotated by 9 (±3)° from the ac plane on the projected structure along the chain axis with a torsion angle between the naphthalene and benzobisthiazole rings of 23°.     

Synthesis, Structures and Luminescent Properties of Two New Cd(II) Coordination Polymers Based on V-Shaped 3,3′,4,4′-Oxidiphthalic Acid

Two new Cd(II) coordination polymers, namely [Cd₂(H₂OA)₂(μ₂-H₂O)(H₂O)₆] _n ·3nH₂O (1) and [Cd₂(H₂OA)(phen)₂] _n ·nH₂O (2) (H₄OA = 3,3′,4,4′-oxidiphthalic acid, phen = 1,10-phenanthroline) have been synthesized by combining H₄OA or H₄OA and phen with Cd(II) salts under hydrothermal conditions. Single-crystal X-ray diffraction analysis reveals that 1 features a hydrogen-bond directed two-dimensional (2D) layered structure constructed from alternating left- and right-handed double strand helical chains, 2 represents a one-dimensional (1D) chain structure with the phen molecules dangling on it, which is further extended into a three-dimensional (3D) supramolecular framework through strong face-to-face π···π interactions. In addition, luminescent properties of these two compounds were also investigated in the solid state at room temperature.     

Fluorescence Properties Change of Lanthanide Coordination Polymers Dispersed in Mesoporous SBA-15 by Energy Transition Process

Four lanthanide coordination polymers, {[Ln(HPDA)(PDA)(H₂O)₂]·4H₂O} _n (Ln?=?Sm (1), Eu (2), Tb (3)) and {[Sm₃(H₂PDA)₂(HPDA)₂(PDA) (OH)₅(H₂O)₃]·2dta·4H₂O} _n (4) (H₂PDA?=?pyridine-2,6-dicarboxylic acid, dta?=?diethyl amine), have been synthesized under hydrothermal conditions and were characterized by elemental analysis, IR spectrometer, and single-crystal X-ray crystallography. In the complexes 1–3, the 1D chains are assembled into 2D layer by hydrogen bonds formed between the carboxyl groups, and were further assembled into 3D framework by hydrogen bonds and π–π stacking interactions. In complex 4, each Sm³⁺ ion connected to the neighboring Sm³⁺ ion through bridging carboxyl oxygen atoms, and then give rise to a new 2D layered open-framework structure. The 3D supramolecular structure of 4 is constructed through hydrogen-bonding and π–π stacking interactions between adjacent metal–organic polymeric coordination chains. Complexes 1–3 were dispersed in mesoporous materials SBA-15 in DMF solution (denoted as ML-SBA-15, ML?=?1, 2, 3), which were characterized by XRD, IR, and fluorescence spectra. Compared to the complexes 1–3, the photoluminescence efficiency of hybrid material was improved by the energy transition between mesoporous materials and the complexes. The complexes encapsulated in mesoporous materials SBA-15 exhibited stronger luminescence intensity and longer fluorescence lifetime.