Diaminostilbene-2,2 ′ - Disulfonic Acid Research Articles

Controlling the microphase morphology and performance of cross-linked highly sulfonated polyimide membranes by varying the molecular structure and volume of the hydrophobic cross-linkable diamine monomers

Morphological control is essential for tuning the performance of polymer electrolyte membranes (PEMs). Block copolymerization is an effective but complicated way to control the morphology of PEMs. It is urgent to explore a simple alternative method to achieve this target. Herein, the molecular engineering strategy that changes the molecular structure and volume of hydrophobic cross-linkable diamine and introduces a hydrophobic network structure was used to optimize the microphase morphology of sulfonated polyimides (SPIs). Three diamine monomers containing tetrafluorostyrol pendant groups have been synthesized (4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene-1,3-diamine (TFVPDM), 1,3-bis(2-trifluoromethyl-4-amino-phenoxy)-5-(2,3,5,6-tetrafluoro-4-vinylphenoxy)benzene (6FTFPB), 2,2-bis(3-amino-4-(2,3,5,6-tetrafluoro-4-vinylphenoxy)phenyl)hexafluoropropane (6FATFVP)). Based on these monomers, 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDSA) and 1,4,5,8-naphthalenetetracarboxylicdianhydride (NTDA), three cross-linked SPIs (CSPIs: CSPI-T-10, CSPI-TP-10, CSPI-AP-10) with similar ion-exchange capacity (IEC) value of 2.29–2.46 meq. g−1 but different main-chain structures were prepared through polycondensation and thermal cross-linking process. The introduced hydrophobic cross-linked structure improves the oxidative stability and methanol resistance of CSPI membranes. The CSPI membranes prepared from cross-linkable hydrophobic diamine with larger molecular volume and containing hydrophobic structural units in the main chain exhibit more pronounced phase separation morphology and higher proton conductivity. Moreover, the methanol resistance of CSPI membranes is dependent on the combined effect of IEC, degree of crosslinking (DC), and main-chain structure. The higher DC and main-chain containing hydrophobic structure are beneficial for enhancing the methanol resistance. The CSPI-AP-10, which was prepared from the 6FATFVP with the largest molecular volume, more hydrophobic cross-linkable pendant groups and hydrophobic linkages, exhibits the best performance. The CSPI-AP-10 membranes showed high proton conductivity and excellent methanol resistance. The direct methanol fuel cells (DMFCs) assembled from CSPI-AP-10 have a high max power density (PDmax) of 106.2 mW cm−2 in 2 M methanol and 75.1 mW cm−2 in 10 M methanol. The results indicated that the CSPI-AP-10 was a promising candidate as a PEM in DMFC application.

A novel negatively charged nanofiltration membrane with improved and stable rejection of Cr (VI) and phosphate under different pH conditions

Nanofiltration (NF) membrane has an extensive application in the field of water treatment, but weakly negative surface-charge and even charge inversion in acidic environment restrict wide applications of traditional aromatic polyamide (PA) thin film composite (TFC) NF membrane in a broad pH range. In this work, 4, 4′-diaminostilbene-2, 2′-disulfonic acid (DSDA), a novel acidic aqueous monomer, was introduced into interfacial polymerization to fabricate a TFC NF membrane with enhanced negative charge and pH stability. The effects of interfacial polymerization parameters were investigated to improve membrane performance. The optimal membrane exhibits a pure water permeance (PWP) of 10.0 ± 0.5 L m−2 h−1·bar−1 and a high Na2SO4 rejection (i.e., ~97.0%). The resultant membrane remains a strongly negative charge when the pH value is changed from 2 to 12. Due to enhanced negative charge, Donnan exclusion plays a significant role in membrane separation process, which results in a huge superiority in removal of Na2SO4, Na3PO4 and K2Cr2O7 in a broad pH range especially in acidic environment. Hence, it is demonstrated that the negative-charged NF membrane prepared in this work has improved and stable separation performance under a broad pH range, which expands application scopes of NF membrane, especially in removing Cr (VI) and phosphate in acidic environments. Besides, this study also provides a feasible route for preparation of suitable TFC NF membrane for working in acidic environment via introducing strongly acidic groups in selective layer.

Trifluoromethyl and benzyl ether side groups containing novel sulfonated co-poly(ether imide)s: Application in microbial fuel cell

A new diamine monomer namely 4,4′-((2′,5′-bis(benzyloxy)-3,3′'-bis(trifluoromethyl)-[1,1′:4,4′'-terphenyl]-4,4′'-diyl)bis(oxy))dianiline (TADBE) was prepared. A series of sulfonated co-poly(ether imide)s was synthesized using this diamine as one of the co-monomers along with 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA) on reaction with a six-membered dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTDA). The degree of sulfonation (DS, 60-90) of the copolymers was controlled by varying the feed ratio of TADBE/DSDSA and the obtained copolymers were designated as DBN-XX (XX = 60, 70, 80 and 90, which signifies the DSDSA feed percentage). The copolymer structures and compositions were confirmed by NMR and FTIR analysis. Membranes were prepared through solution casting route using dimethyl sulfoxide as solvent followed by high-temperature annealing. The membranes showed high thermal (e.g., DBN-60, Td10 ∼327 °C) and mechanical stabilities (e.g., DBN-60, tensile strength ∼94 MPa), good hydrolytic stability (e.g., DBN-60, >99 retain wt%) and low water uptake (e.g., DBN-60, ∼17 wt% at 80 °C). Polymer composites were prepared by loading different weight percentages of cerium oxide (2.5, 5 and 7.5 wt%, respectively) to enhance the peroxide stability of the copolymer DBN-90 with high DS value. TEM and AFM studies of the pristine membranes confirmed a well phase separated morphology and this was further supported from SAXS profiles. The proton conductivity (e.g., DBN-90, ∼244 mS cm−1) and microbial fuel cell performance (e.g., DBN-90, power density ∼576 mW m−2) of the membranes were comparable to Nafion® 117 (power density ∼563 mW m−2) under similar experimental conditions.

Novel Sulfonated Co-poly(ether imide)s Containing Trifluoromethyl, Fluorenyl and Hydroxyl Groups for Enhanced Proton Exchange Membrane Properties: Application in Microbial Fuel Cell.

A hydroxyl group containing new cardo diamine monomer was synthesized, namely 9,9-bis (hydroxy- (4'-amino(3-trifluoromethyl)biphenyl-4-oxy)-phenyl)-9H-fluorene (mixture of isomers, HAPHPF). HAPHPF, along with a sulfonated diamine monomer, 4,4'-diaminostilbene-2,2'-disulfonic acid (DSDSA), was used to prepare a series of new sulfonated copolyimides by polycondensation with 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). The degree of sulfonation (DS < 1) was adjusted by the feed ratio of DSDSA/HAPHPF and the copolymers were named as DHN-XX, where XX denotes the mole percentage of DSDSA (XX = 50, 60, and 70). The copolymers showed high molecular weights. The copolymer structure and composition were confirmed by FTIR and NMR techniques. Copolymer membranes were prepared through solution cast route by using dimethyl sulfoxide as a solvent. The membranes showed high thermal, mechanical, hydrolytic and peroxide radical stability, and low water uptake and low swelling ratios. Well-separated hydrophilic and hydrophobic phase morphology was observed in TEM and AFM images of the copolymer membranes and was further supported by the SAXS studies. The proton conductivity of the DHN-70 was as high as 97 mS cm-1 at 80 °C and the value is significantly higher than that of the nonhydroxylated analogue. The membranes also showed superior microbial fuel cell (MFC) performance, similar like Nafion 117 under similar test conditions. The chemical oxygen demand removal values provide substantial evidence that the fabricated membranes can be utilized in bioelectrochemical systems.

Facile synthesis of 4,4′-diaminostilbene-2,2′-disulfonic-acid-grafted reduced graphene oxide and its application as a high-performance asymmetric supercapacitor

In this study, a novel 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDSA)-functionalized reduced graphene oxide (DASDSA-rGO) was prepared via simple refluxing method involving GO and DASDSA in the presence of ammonia solution followed by reduction with hydrazine hydrate. FTIR spectroscopy, Raman scattering, X-ray photoelectron spectroscopy (XPS), and XRD analyses confirmed the successful functionalization and reduction of GO in DASDSA-rGO. The FTIR and XPS analyses also confirmed covalent bond formation between DASDSA and graphene. The DASDSA spacer successfully minimized the restacking of rGO sheets as observed from FESEM analysis. Several redox transition states and SO3H groups of grafted DASDSA moieties provided excellent pseudocapacitance performance of the DASDSA-rGO electrode. The DASDSA-rGO electrode showed high specific capacitance (C) value of 1042Fg−1 at a current density of 1Ag−1, good cycling stability (95% capacitance retention after 3000 cycles), and excellent rate capability in a three-electrode setup. The DASDSA-rGO (positive electrode) and rGO (negative electrode) were assembled to prepare an asymmetric supercapacitor (ASC) device. The power density values of the ASC device were calculated to be 650 and 7800Wkg−1 at energy density values of 37.37 and 23.78Whkg−1, respectively. The ASC device exhibited C value of 159Fg−1 at 1Ag−1 and displayed 86% retention in C after 8500 cycles. The EIS data of the three-electrode system and ASC device were fitted with Z-views to determine the different resistance components after a different number of charge–discharge cycles in a cycling stability test.

Sulfonated copolyimides containing trifluoromethyl and phosphine oxide moieties: Synergistic effect towards proton exchange membrane properties

This paper reports the synthesis and characterization of a series of new semi-fluorinated sulfonated copolyimides (co-SPI) using a new trifluoromethyl and phosphine oxide containing diamine monomer, namely bis[4-(4′-aminophenoxy)-3-trifluoromethyl phenyl] phenylphosphine oxide (DFPPO). The copolymers were prepared by one pot polycondensation reaction of a mixture of two diamine monomers, namely 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA) and DFPPO with the equimolar amount of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). All these copolymers were soluble in several organic solvents and size exclusion chromatography indicated the formation of high molar masses. The membranes prepared from these copolymers by solution casting route showed good mechanical properties. The polymers were characterized by FTIR and NMR spectroscopic techniques that confirmed the polymer repeat unit structures. The degree of sulfonation of the copolymers was determined from 1H NMR signal intensities. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) images of the membranes showed phase separated morphology. In general, all the copolyimides showed high proton conductivity and reasonably high oxidative and hydrolytic stability. The co-SPI membrane DFPNH-90 (90% degree of sulfonation) with IECW=2.86 mequiv g−1 showed proton conductivity as high as 237mScm−1 at 80°C.

Sulfonated poly(ether imide)s with fluorenyl and trifluoromethyl groups: Application in microbial fuel cell (MFC)

A series of fluorenyl and trifluoromethyl groups containing co-poly(ether imide)s (S-co-PIs) have been prepared from a new diamine monomer; 9,9-bis(3-methoxy-4-(4-amino(3-trifluoro-methyl)biphenoxy)phenyl)-9H-fluorene (APHPF). The polymers were prepared by the polycondensation reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) with two different diamines; APHPF and 4,4′-diaminostilbene-2,2′-disulfonicacid (DSDSA) as a co-monomer. The monomer and polymers were well characterized by 1H NMR and ATR-FTIR spectroscopies. The co-polymers were soluble in various organic solvents and membranes were prepared from solution cast route. The S-co-PIs showed high thermal and mechanical stability. TEM and AFM results supports the formation of phase separated morphology with well separated ionic-clusters. All these S-co-PIs displayed reasonably high proton conductivity. One of the copolymers (DAN-80; IECw ∼2.27meqg−1) exhibited a proton conductivity as high as 149mScm−1 which was comparable to that of Nafion® 117 (165mScm−1) at 80°C. The co-polymers maintain a good balance between water-uptake and swelling ratios and peroxide resistance. Microbial Fuel Cell (MFC) performance of the co-polymers were evaluated DAN-80 exhibited a similar performance like Nafion® 117 under similar test condition.

Sulfonated polyimides containing triphenylphosphine oxide for proton exchange membranes

A series of sulfonated co-polyimides (co-SPI) were prepared by one pot polycondensation reaction of a combination of diamines namely; 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA) and prepared non-sulfonated diamine (DATPPO) containing triphenylphosphine oxide with 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). All these soluble co-SPI gave flexible membranes with high thermal stability and showed good mechanical property. Transmission electron microscopy (TEM) analysis revealed the microphase separated morphology with well-dispersed hydrophilic (cluster size in the range of 5–55 nm) domains. The co-SPI membranes showed high oxidative and hydrolytic stability with higher proton conductivity. All these co-SPI membranes exhibited low water uptake and swelling ratio. The co-SPI membrane TPPO-60 (60% degree of sulfonation) with IECW = 1.84 mequiv g−1 showed high proton conductivity (99 mS cm−1 at 80 °C and 107 mS cm−1 at 90 °C) in water with high oxidative (20 h) and hydrolytic stability (only 5% degradation in 24 h).

Triphenyl amine containing sulfonated aromatic polyimide proton exchange membranes

A series of new sulfonated co-polyimides (co-SPI) were prepared by the polycondensation reaction of two diamines namely; 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA) and 4,4′-diaminotriphenylamine (DATPA) with 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). All the copolymers showed good solubility and flexible membranes were obtained from their DMAc solution. The transmission electron microscopy (TEM) of the polymers revealed microphase separated morphology with well-dispersed hydrophilic (around 5–100nm) and hydrophobic domains. The SPI membrane DTN-80 (80% degree of sulfonation) with ionic exchange capacity (IECw) of 2.74mequivg−1 showed significantly higher proton conductivity (207mScm−1) at 80°C in water as compared to the perfluorinated Nafion® 117 (135mScm−1) under similar test conditions. All these co-SPI membranes showed lower oxygen permeability (for DTN-80, PO2=0.9barrer) than Nafion® 117 (PO2=3.6barrer).

Proton exchange properties of flexible diamine-based new fluorinated sulfonated polyimides

A series of new semifluorinated sulfonated polyimide copolymers (DHNHXX) were prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA) and 1,4-bis-[{2′-trifluoromethyl-4′-(4′′-aminophenyl)phenoxy}] benzene (HQA). The degree of sulfonation of DHNHXX was varied by changing the molar ratio of the sulfonated diamine, DSDSA to the non-sulfonated diamine, HQA. The flexible DHNHXX membranes showed high thermal stability (desulfonation temperature above 270 °C) and good mechanical properties. The oxidative stability of DHNHXX improved with increasing the fluorine content. DHNHXX showed anisotropic dimensional changes, and good water stability (did not dissolve for up to 415 h), higher than many other sulfonated polyimides. Transmission electron microscopy (TEM) analysis revealed cluster-like microstructures for the DHNHXX membranes, suggesting good phase-separated morphology. DHNH70 with IEC = 2.10 meq. g−1 exhibited high proton conductivity, with a maximum up to 129 mS cm−1 at 90 °C in water.

Naphthalene dianhydride based semifluorinated sulfonated copoly(ether imide)s: Synthesis, characterization and proton exchange properties

A series of semifluorinated sulfonated copoly(ether imide)s (co-SPI) was synthesized by one pot high temperature polycondensation reaction using a sulfonated diamine, 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) and a fluorinated quadri diamine (QA). The structures of the resulting co-SPIs were investigated by FTIR and NMR spectroscopy. The polymers had high molecular weight and gave tough, flexible and transparent membranes. Oxidative stability of the membranes was improved by introducing trifluoromethyl substituents in the copolymer structure and the copolymers also exhibited superior mechanical property higher than many other SPIs. The co-SPI membrane showed significantly high proton conductivity and low activation energy in water medium. Microscopic analyses revealed that well-dispersed hydrophilic domains contribute to better proton conducting properties.

Synthesis and characterization of new fluorinated poly(ether imide) copolymers with controlled degree of sulfonation for proton exchange membranes

► New semifluorinated poly(ether imide) PEM material. ► High mechanical strength and good thermal stabilities. ► Low swelling in water. ► High proton conductivity (up to 3.45 × 10 −2 S cm −1 ). A series of random sulfonated polyimide (SPI) with controlled sulfonation degrees were synthesized by one step high temperature polycondensation reaction using a commercially available sulfonated diamine, 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA), 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA), and a fluorine containing quadri diamine (QA). Transparent, flexible and mechanically strong thin films were prepared by the solution–evaporation method using dimethylacetamide (DMAc). The structures of the resulting SPIs were confirmed by FTIR and 1 H NMR spectroscopy. The polymers showed the onset of decomposition at around 290–300 °C for the ionic moieties and above 570 °C for the polymer backbone. The membranes exhibited good proton conductivity at higher sulfonation content which was found in the range of Nafion ® 117 and were also comparable to many typical proton exchange membranes. A clear microphase separated structure was observed under transmission electron microscopy (TEM) which indicated the formation of hydrophilic and hydrophobic domain throughout the membrane.

New poly(ethylene oxide) soft segment-containing sulfonated polyimide copolymers for high temperature proton-exchange membrane fuel cells

The synthesis and characterization of a series of new poly(ethylene oxide) (PEO) soft segment-containing six-member ring sulfonated polyimide (SPI) copolymers are described in this paper. One-step high temperature polymerization method was used to prepare the SPI copolymers from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA), and diamine-terminated poly(ethylene oxide) (PEO-diamine, MW = 1000). The relative ratio of the sulfonic acid-containing hard segments to the PEO-containing soft segments was controlled through varying the molar ratio of DSDSA to PEO-diamine. Flexible, transparent, and mechanically strong free-standing membranes were successfully obtained. The membranes were characterized with ion-exchange capacity, Fourier transform infrared spectra, thermogravimetric analysis, water sorption, proton conductivity, and fuel cell performance measurements. The results showed that the new SPI membranes exhibited desirable mechanical properties and thermal stability as well as better proton conductivities than Nafion ® 115 at high relative humidity (RH) levels (>50%) at both 70 and 120 °C. The results from the fuel cell performance measurements indicated that the SPI membrane containing 5 mol% (12.4 wt.%) PEO soft segments had similar fuel cell performance as Nafion ® 112 at 70 °C and 80% RH, but better fuel cell performance than Nafion ® 112 when the current density was higher than 0.32 A/cm 2 at 120 °C and 50% RH.

The photocatalytic degradation of amino and nitro substituted stilbenesulfonic acids by TiO 2/UV and Fe 2+/H 2O 2/UV under aqueous conditions

The photodegradation products of 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNSDA), 4-amino-4′-nitrostilbene-2,2′-disulfonic acid (ANSDA) and 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDA) imparted by UV, TiO 2/UV and Fe 2+/H 2O 2/UV were characterized by IC, HPLC and LC-ESI-MS/MS. Direct photolysis with UV light allowed the transformation of trans-isomers to the corresponding cis-isomers followed by degradation to aromatic aldehydes and carboxylic acids. Whilst both TiO 2/UV and Fe 2+/H 2O 2/UV processes mineralized the model compounds, Fe 2+/H 2O 2/UV process was more rapid than TiO 2/UV.

Synthesis and characterization of new sulfonated polyimides as proton-exchange membranes for fuel cells

The synthesis and characterization of a series of new sulfonated polyimides are described. One-step high temperature polymerization method was used to prepare the sulfonated polyimide copolymers from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA), and other three common diamines, i.e., 4,4′-oxydianline (ODA), 4,4′-methylene dianiline (MDA), and 4,4′-(9-fluorenylidene)dianiline (FDA). The sulfonation degree of the copolymers was regulated through variation of the molar ratio of DSDSA to the common diamines. Flexible, transparent, and mechanically strong membranes were successfully obtained. The membranes were characterized with Fourier transform infrared spectra, thermogravimetric analysis, ion-exchange capacity, and proton conductivity measurements. These results showed that the membranes had good thermal stability and exhibited high conductivity at high relative humidity levels, especially in liquid water at 70 °C. At high temperatures of above 140 °C, the membranes displayed higher conductivities than Nafion ® membranes because of their high activation energies.

Removal of amino and nitro-substituted stilbenesulfonic acids from aqueous environment: biosorption and biodegradation by isolated Aspergillus awamori ( Nakazawa)

Asperillus awamori ( Nakazawa) an effective fungal strain for removal of substituted aromatic sulfonic acids was isolated from the aerobic sludge of an industrial effluent treatment plant in Hyderabad, India. It was tested for the removal of 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNSDA), 4-amino-4′-nitrostilbene-2,2′-disulfonic acid (ANSDA) and 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDA) from industrial waste waters and the experimental parameters were optimized. The effects of amino and nitro substituents on biosorption and biodegradation of aromatic sulfonic acids were investigated. Soluble starch was found to be an effective and economical source of carbon. The initial pH of the media was in between 4.0 and 7.0 for growth of the fungi and removal of the test compounds. Two different mechanisms viz., biosorption and biodegradation were responsible for the removal of the test compounds by Asperillus awamori. The extent of removal by both the mechanisms was found to be dependent upon the functional groups present on the aromatic rings. Within 5 days, 99% of 50 mg/L of DNSDA was removed by biosorption while 72% of ANSDA and 53% of DASDA were adsorbed as well as converted into corresponding products. Biosorption was found to be pH-dependent and dominant when it reached around 2.5. The isolated Asperillus awamori ( Nakazawa) was found to be quite effective for removal of the test compounds in complex environmental matrices.

Silica coating and photochemical properties of layered double hydroxide/ [formula omitted]-diaminostilbene– [formula omitted]-disulfonic acid nanocomposite

Organic ultraviolet (UV) rays absorbents have been used as sunscreen materials, but they may pose a safety problem when used at high concentration. In order to prevent direct contact of organic UV rays absorbent to the human skin, a typical organic UV-absorbent, 4 , 4 ′ -diaminostilbene- 2 , 2 ′ -disulfonic acid (DASDSA), was intercalated into Zn 2Al layered double hydroxide (Zn 2Al-LDH) by coprecipitation reaction. However, deintercalation of DASDSA from Zn 2Al-LDH, by the anion exchange reaction with carbonate ion, was observed. Therefore, Zn 2Al-LDH/DASDSA was directly coated with silica by means of polymerization technique based on the Stöber method. Silica coating effectively depressed the deintercalation of DASDSA from Zn 2Al-LDH. The amorphous silica was confirmed by XRD, SEM, TEM and FT-IR. The deintercalation behaviors as well as UV-shielding properties were investigated for coated particles.

LC‐PDA and LC‐ESI‐MS separation and determination of process‐related substances arising from stilbene‐type fluorescent whitening agents. Application to monitoring of their photodegradation products in industrial effluents and aqueous environmental systems

A simple and rapid gradient elution high-performance liquid chromatographic method using photodiode array and electrospray ionization mass spectrometric detectors was developed for separation and determination of the process-related substances and photodegradation products of stilbenesulfonic acids, viz. 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNSDA), 4-amino-4'-nitrostilbene-2,2'-disulfonic acid (ANSDA), and 4,4'-diaminostilbene-2,2'-disulfonic acid (DASDA) in industrial waste waters. Gradient elution was carried out using ammonium acetate and acetonitrile as mobile phase and an Inertsil-ODS 3V column for separation. The negative-ion electrospray ionization mass spectra containing [M-H]- ions of sulfonic acids allowed molecular mass determination of unknowns and the structures were proposed on the basis of the fragment ions in the MS/MS spectra.

Direct coating for layered double hydroxide/4,4′-diaminostilbene–2,2′-disulfonic acid nanocomposite with silica by seeded polymerization technique

Organic ultraviolet (UV) ray absorbents have been used as sunscreen materials, but may pose a safety problem when used at high concentration. In order to prevent direct contact of organic UV rays absorbent by the human skin, an organic UV absorbent such as 4,4′-diaminostilbene-2,2′-disulfonic acid (DASDSA) was intercalated into Zn 2Al-layered double hydroxide (Zn 2Al-LDHs) by coprecipiation reaction. The problem of deintercalation of organic molecules from LDHs by the anion exchange reaction with carbonate ion could be greatly depressed by forming a protection film of silica on the surface. Zn 2Al-LDH/DASDSA was directly coated with silica by means of a polymerization technique based on the Stöber method. The deintercalation behavior as well as UV-shielding properties were investigated for coated particles.

Hemolysate-filled polyethyleneimine and polyurea microcapsules as potential red blood cell substitutes: effect of aqueous monomer type on properties of the prepared microcapsules

In this paper, we describe the synthesis and characterization of rabbit hemolysate-filled polyethyleneimine (PEI)- or polyurea (PU)-type artificial red blood cells (ARBCs) with different membrane compositions. These microcapsules were prepared by making use of the interfacial polymerization (IP) reaction between the water-soluble amine monomers (triethylamine (TEA), ethylene glycol-bis(β-aminoethyl ether)- N, N′-tetraacetic acid (EGATA), diethylenetriamine (DETA), tetramethyl diaminomethane (TMDAM), piperazine hexahydrate (PPHH), l-lysine monohydrochloride (LLMH) or PEI) and 2,4-toluylene diisocyanate (TDI) as an oil-soluble shell monomer. The resultant microcapsules were spherical and with mean diameters of 8.71–63.33 μm. Microcapsules having sulfonic acid groups on their surfaces were prepared by using a combination of the functional amines (DETA, LLMH or PEI) and 4,4′-diaminostilbene-2,2′-disulfonic acid (DASSA). Oxygen-binding abilities of the ARBCs were measured by a Clark-type oxygen electrode. The obtained results revealed that the highest oxygen-binding abilities were obtained with the PU-ARBCs prepared with DETA alone or in combination with EGATA. Unfortunately, these microcapsules exhibited large diameters and wider size distribution curves (span values ( S)=1.3, 1.7, geometric standard deviation ( σ g)=1.85, 2.18, respectively). However, the novel ARBCs (sulfonated PU-PEI graft copolymer membrane microcapsules (SPU/PEI-ARBCs)) prepared had good oxygen affinity, the smallest mean diameter ( d=8.71 μm) and the best distribution ( S=0.9, σ g=1.48) and a flow behavior identical to rabbit RBCs. Therefore, these unique microcapsules can be recommended for scale-up considerations as a promising blood substitute.