COCl Groups Research Articles

Exploration of self-crosslinking induced surface modification using APTES on the PA RO membrane for excellent anti-fouling performance

The physicochemical properties of the polyamide reverse osmosis (PA RO) membrane surface play a crucial role in membrane fouling. In this work, a silicon-based material, γ-Aminopropyl triethoxysilane (APTES), was incorporated onto the PA membrane surface by self-crosslinking induced surface modification to improve its antifouling properties. FTIR and XPS analyses reveal that APTES primarily bonded to the pristine PA membrane via amidation between –NH2 groups in APTES and residual –COCl groups on the membrane surface, and then combined with each other to form Si–O–Si groups (even Si–O–Si networks). The incorporation of APTES reduces the membrane surface energy and roughness, and the surface potential of the membranes can be adjusted by varying the APTES addition. Meanwhile, the pure water permeance of the APTES-PA membrane reached ~3.77 LMH/bar while maintaining a NaCl rejection of ~98.65 %. Additionally, although the negative charge of the APTES-PA (M0.15) membrane increases, the antifouling against electropositive small molecular foulants is enhanced, mainly due to the low-surface-energy of the APTES-modified layer. Furthermore, the stability of the APTES-modified layer in the presence of electronegative small molecular foulants with strong decontamination capabilities can be reinforced by a simple high-temperature heat treatment. Broadly speaking, surface modification of the PA RO membrane by APTES combining grafting with self-crosslinking induced method is beneficial for its anti-fouling and reuse.

Selective Cleavage and Structural Stability of Double Crosslinked Aromatic Polyamide Porous Materials

AbstractA porous, crosslinked aromatic polyamide having COCl and COOH groups (referred to as PA herein) prepared had a mesoporous structure and comprised agglomerates of particles with average diameters of approximately 30 nm. The PA was found to swell with significant deformation in response to water vapor, but was almost unchanged after exposure to toluene vapor. The polymeric structure returned to its original porous morphology after removal of the solvents, demonstrating that the PA possessed affinity for specific solvents and shape memory. The chemical composition and porous structure of the PA were also not affected by heating to 330 °C. The COCl groups in the PA could be modified by reaction with 2,4,6‐triaminopyrimidine (TAP), resulting in a doubly crosslinked structure based on the reaction with the TAP as well as the existing amide moieties in the polymer. The degree of modification was highly dependent on the reaction solvent used. The porous structure of the PA was essentially unchanged after this modification. The TAP‐based crosslinks in the modified PA could be selectively cleaved along with vaporization of the TAP by heating at 330 °C, which no change to the porous structure. Thus, the PA showed excellent heat resistance and structural stability.

Synthesis of reactive polyamide porous materials and introduction of crosslinking

ABSTRACT Porous crosslinked aromatic polyamides were prepared in a single-step process by reacting a triacid chloride monomer with a diamine monomer having COOH groups via a precipitation polymerization method. The resulting materials were agglomerates of polyamide particles having COCl and COOH groups with average diameters of 30–70 nm and average pore diameters in the range of ca. 20–40 nm. The concentration of COCl groups and the porous structure were significantly affected by the monomer ratio, the total monomer concentration and the reaction solvent. These COCl groups were subsequently modified by reaction with 1,8-diaminooctane in three different solvents, and the extent of modification depended strongly on the solvent. This modification produced aromatic polyamides having two types of crosslinking, based on of the 1,8-diaminooctane and the aromatic polyamide product, which were cleaved in different temperature ranges. The COCl groups introduced were found to have high reactivity and react with NH2 groups even in water, prior to hydrolysis.

Constructing positively charged acid-resistant nanofiltration membranes via surface postgrafting for efficient removal of metal ions from electroplating rinse wastewater

To efficiently recycle metal ions from electroplating wastewater, a positively charged acid-resistant nanofiltration membrane was prepared by coupling interfacial polymerization and postgrafting modification with an ethanol grafting solution containing N-(3-aminopropyl)-imidazole (ANPI). Ethanol, as the grafting solvent, not only slightly swelled the original polyamide (PA) layer but also is mutually miscible with n-hexane, which prevented the formation of additional PA layers. ANPI, as the grafting monomer, was covalently bound to the -COCl groups of the PA layer to guarantee grafting stability. Due to the inhibited hydrolysis of the -COCl group by ethanol, more ANPI was grafted on the PA layer, which could be easily protonated under low pH. This resulted in a looser, thinner and positively charged selectivity layer. The membrane permeability was improved by 56.0 ± 0.55% with high interception performance (> 98% for Cu2+ and Ni2+ ions) in electroplating rinse wastewater. The formed positive protective layer prevented H+ ions from attacking the –CO-NH- bonds, resulting in strong stability after immersion in 10 wt% H2SO4 and H3PO4. Therefore, the obtained membrane shows promise for application in highly acidic wastewater.

Covalent functionalization of graphene using polyacryloyl chloride and performance of functionalized graphene–epoxy nanocomposite

A facile approach to functionalize mild acid treated exfoliated graphite nanoparticles (GnPs) was established using poly (acryloyl chloride) (PACl). The reaction between the acyl chloride groups of PACl and the hydroxyl group of mild acid treated GnPs (AGNPs) facilitated the formation of “ester linkage.” The remaining –COCl groups of PACl were covalently bonded with epoxy to form the hybrid nanocomposite. Structure of GnPs was not perturbed upon mild acid treatment. Successful functionalization was confirmed via thermal stability and morphological observations. The structural aspects and properties of the nanocomposites were evaluated via spectroscopic measurements, thermo‐mechanical analysis, and scanning electron microscopic observations. Improved interfacial adhesion between epoxy and functionalized GnPs was evaluated via SEM. The nanocomposite exhibited an enhancement of mechanical properties at lower filler content (1.0 wt%), which resulted in an increase in flexural strength and flexural modulus by 15 and 22%, respectively. POLYM. COMPOS., 39:3119–3128, 2018. © 2017 Society of Plastics Engineers

Apelin-APJ effects of ginsenoside-Rb1 depending on hypoxia-induced factor 1α in hypoxia neonatal cardiomyocytes.

To investigate whether ginsenoside-Rb1 (Gs-Rb1) inhibits the apoptosis of hypoxia cardiomyocytes by up-regulating apelin-APJ system and whether the system is affected by hypoxia-induced factor 1α (Hif-1α). Neonatal rat cardiomyocytes were randomly divided into 6 groups: a control group, a simple CoCl group, a simple Gs-Rb1 group, a CoCl and Gs-Rb1 hypoxia group, a CoCl and 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1) group, a CoCl and YC-1 group and a Gs-Rb1 group, in which YC-1 inhibits the synthesis and accelerates the degradation of Hif-1a. The concentration of CoCl, Gs-Rb1 and YC-1 was 500 μmol/L, 200 μmol/L and 5 μmol/L, respectively; the apoptosis ratio was analyzed with a flow cytometer; and apelin, APJ and Hif-1α were assayed with immunocytochemistry, Western blot assays and reverse transcription polymerase chain reaction (RT-PCR). (1) The anti-apoptosis effect of Gs-Rb1 on hypoxia cardiomyocytes was significantly inhibited by YC-1; (2) Hypoxia significantly up-graded the expression of mRNA and protein of apelin; this effect was further reinforced by Gs-Rb1 and significantly inhibited by YC-1; (3) Gs-Rb1 further strengthened the expression of APJ mRNA and APJ proteins once hypoxia occurred, which was significantly inhibited by YC-1; (4) Gs-Rb1 significantly increased the expression of Hif-1α, which was completely abolished by YC-1; (5) There was a negative relationship between AR and apelin (or APJ, including mRNA and protein), a positive correlation between apelin (or APJ) protein and Hif-1a protein, in hypoxia cardiomyocytes. The apelin-APJ system plays an important role in the anti-apoptosis effect of Gs-Rb1 on hypoxia neonatal cardiomyocytes, which was partly adjusted by Hif-1α.

Characterization of Aromatic Polyamide Particles Containing Carboxylic Acid and Carboxylic Acid Chloride Groups and Their Modification in Water

Two types of aromatic polyamide particles were prepared from 4,4′-diphenyldicarbonyl chloride and 3,5-diaminobenzoic acid in a reaction solution containing water or pyridine. Particles obtained using water (PA-water) were coarse spheres containing COOH groups with a diameter of 1 µm. Particles obtained using pyridine (PA-pyridine) were smooth spheres containing COOH and COCl groups with a diameter of 80 nm. The molecular weight of PA-pyridine was less than that of PA-water. During modification of PA-pyridine using 4′-aminobenzo-15-crown-5-ether, the COCl groups reacted with NH2 groups of the crown ether in water, resulting in attachment of the crown ether to the particle surface.

Surface modification of poly(ethylene-co-acrylic acid) with amino-functionalized silica nanoparticles

In this work we studied the possibility to achieve a hybrid-surface through the modification, via a facile wet chemical process, of the surface of films of poly(ethylene-co-acrylic acid) (EAA) with amino-modified silica nanoparticles. Films of EAA were preliminarily activated by the introduction of –COCl groups on their surface. Silica nanoparticles were thereafter covalently bound on the polymeric surface as confirmed by FTIR, ATR-FTIR, XPS, NMR and SEM determinations. The nanoparticles formed a multilayer on the film surface and covered almost uniformly the whole film surface. Direct measurements of superficial amino groups by titration allowed us to detect a concentration of about 18 nmol cm−2. The presence of this uniform layer of nanoparticles bearing polar groups strongly changed the wettability of the material as confirmed by static contact angle measurements that passed from 87° of the neat EAA to about 30° of the amino-functionalized silica nanoparticles modified material.

Influence of water/O2 plasma treatment on cellular responses of PCL and PET surfaces

In this study, low pressure water/O₂ plasma treatment was performed in order to obtain COOH functionalities on the surface of poly-ε-caprolactone (PCL) membranes as well as non-woven polyester fabric (NWPF) discs. The plasma treatments were performed in a cylindrical, capacitively coupled RF-plasma-reactor and then following steps were performed: in situ (oxalyl chloride vapors) gas/solid reaction to convert -OH functionalities into -COCl groups; and hydrolysis under open laboratory conditions using air moisture for final-COOH functionalities. COOH and OH functionalities on modified surfaces were detected quantitatively by using fluorescent labeling technique and an UVX 300G sensor. Electron spectroscopy for chemical analysis (ESCA) was used to evaluate the relative surface atomic compositions and the carbon and oxygen linkages located in non-equivalent atomic positions of untreated and modified surfaces. Atomic force microscope (AFM) analysis showed that nanoscale features of the PCL surfaces are dramatically changed during the surface treatments. Scanning electron microscopy (SEM) results indicated the changes in the relatively smooth appearance of the untreated NWPF discs after the plasma treatment. Periodontal ligament (PDL) fibroblasts were used in cell culture studies. Cell culture results showed that plasma treated PCL membranes and NWPF discs were favorable for the PDL cell spreading, growth and viability due to the presence of functional groups and/or nanotopographies on their surfaces.

Coupled fluorescein isothiocyanate on graphene oxide

In this study, we presented a simple and direct approach for the decoration of graphene oxide (GO) by fluorescent material. In this protocol, the GO functionalized with COCl groups was first prepared by treating with SOCl 2. Fluorescein isothiocyanate (FITC), which is a popular fluorescence probe, was then chemically bonded to the surface of GO sheets, resulting in the formation of FITC-coupled GO hybrid. Fluorescence spectrophotometer, Raman spectroscopy, X-ray photoelectron spectrometer, and Fourier transform infrared spectra were used to demonstrate the successful attachment of FITC to the surface of GO sheets. In addition, the method could be extended to further development of graphene-based nanoelectronics.

Water/O2-Plasma-Assisted Treatment of PCL Membranes for Biosignal Immobilization

The main purpose of this study was to obtain COOH functionalities on the surface of poly-ε-caprolactone (PCL) membranes using low-pressure water/O2-plasma-assisted treatment. PCL membranes were prepared using the solvent-casting technique. Then, low-pressure water/O2 plasma treatments were performed in a cylindrical, capacitively coupled RF-plasma-reactor in three steps: H2O/O2-plasma treatment; in situ (oxalyl chloride vapors) gas/solid reaction to convert –OH functionalities into –COCl groups; and hydrolysis for final –COOH functionalities. Optimization of plasma modification processes was done using the DoE software program. COOH and OH functionalities on modified surfaces were detected quantitatively using the fluorescent labeling technique and an UVX 300G sensor. Chemical structural information of untreated, plasma treated and oxalyl chloride functionalized PCL membranes were acquired using pyrolysis GC/MS and ESCA analysis. High-resolution AFM images revealed that nanopatterns were more affected than micropatterns by plasma treatments. AFM images recorded with amino-functionalized tips presented increased size of the features on the surface that suggests higher density of the carboxyls on the nanotopographical elements. Low-pressure water/O2-plasma-treated and oxalyl chloride functionalized samples were biologically activated with insulin and/or heparin biosignal molecules using a PEO (polyoxyethylene bis amine) spacer. The success of the immobilization process was checked qualitatively by ESCA analysis. In addition, fluorescent labeling techniques were used for the quantitative determination of immobilized biomolecules. Cell-culture experiments indicated that biomolecule immobilization onto PCL scaffolds was effective on L929 cell adhesion and proliferation, especially in the presence of heparin.

Effect of a dipolar self‐assembly monolayer formation on indium‐tin oxide on the performance of single‐layer polymer‐based light‐emitting diodes

AbstractWe report on the use of indium‐tin oxide surface modification, by grafting of highly polar p‐disubstituted benzenes, in the fabrication of light‐emitting diodes. The polar compounds possess COCl or SO2Cl grafting groups and CF3 or NO2 as highly electronegative groups, leading to the formation of a dipolar monolayer, which brings about an increase in ITO work function, thereby reducing the barrier for hole injection into luminescent polymers. We observe that the effect of this self‐assembled monolayer, in terms of light‐onset voltage, efficiency and luminance, is at least comparable to the use of a hole injection layer of doped poly[(3,4‐ethylenedioxy)thiophene] for LEDs using poly({2‐[(2‐ethylhexyl)oxy]‐5‐methoxy‐1,4‐phenylene}vinylene) (MEH‐PPV) and polyfluorene blends as active layers.

Nowy sposob syntezy hydrofobowo modyfikowanego poli(kwasu akrylowego)

A new method of the synthesis of hydrofobically modified poly(acrylic acid) (HMPAA) (Scheme A) is based on a dissolution of initial poly(acrylic acid) (PAA) in thionyl chloride, which at temp. 60 °C reacts with COOH groups so the chloroyl groups COCI create. Chloroyl groups were subjected to partial amidation with dodecylamine and then the unreacted COCl groups were hydrolized to the carboxyl groups. HMPAA obtained this way contained 2.55 % of nitrogen and in aqueous solutions (0.1 M NaCl) showed, in viscometric measurements, the behavior being characteristic for amphiphylic polymers. It means the dependence η s p /c = f(c) (Fig. 2) significantly deviates from a straight line in contrast to the initial PAA (Fig. 1). Further confirmation of an amphiphylic character of HMPAA is the decrease in surface tension of water from 72.7 mN/m (just water) to 42 mN/m (1 % solution of HMPAA), at temp. 25 °C. 1 3 C NMR spectra of PAA and HMPAA (Fig. 4 and 5) were interpreted. In HMPAA spectrum there are additional signals coming from carbon atom of CONH group and from C atoms of aliphatic chain from dodecylamine. An explanation of the differences of the courses of curves of potentiometric titration of PAA and HMPAA (Fig. 6 and 7) is also given.

Soluble self-doped single-walled carbon nanotube

Treatment of single-walled carbon nanotube (SWNT) having carboxylic acid chloride groups at the open end, SWNT–(COCl) n , with polyethyleneimine (PEI) caused amidation reaction between the COCl group and the amine groups of PEI to give functionalized SWNTs. The products were separated into soluble and insoluble parts in chloroform, 1 and 2, respectively. IR data revealed that all the COCl groups reacted with amine groups of PEI to provide 1, whereas unreacted COCl groups remained in 2. 1 was photoluminescent and electrochemically active in the solution. Electron spin resonance (ESR) spectrum of 1 indicated formation of a radical cation on N atoms of PEI. An electric junction, Pt/P3HexTh/ 1/Hg, where P3HexTh is poly(3-hexylthiphene) which usually shows p-type electrically conducting properties, was fabricated. The junction shows rectification of electric current, and this rectification is attributed to the formation of a p–n junction between P3HexTh and 1. These data supported a view that 1 served as an n-type electrically conducting material. Optical and thermal properties of 1 and 2 were also investigated.

Tailoring activated carbon by surface chemical modification with O, S, and N containing molecules

In this work the surface of activated carbon was chemically modified in order to introduce O, S and N containing groups. The activated carbon surface was selectively oxidized with concentrated HNO3 under controlled conditions. Characterization by thermogravimetric analyses, infrared spectroscopy and NaOH titration suggested the formation of mainly -COOH and small amounts of -OH groups, with concentration of approximately 4.10(21) groups/g of carbon. These -COOH functionalized carbons showed high adsorption capacity for metal cations in aqueous solution in the following order: Pb+2>Cu+2>Ni+2 >Cd+2~Co+2>Ca+2 , suggesting a cation exchange mechanism via a surface complex [COO-M+2]. These -COOHsurf groups can be reacted with SOCl2 to produce a surface acylchloride group, -COCl. This surface -COCl group proved to be a very reactive and versatile intermediate for the grafting of different S and N containing molecules onto the carbon surface, such as 1,2-ethaneditiol (EDT-, HSCH2CH2SH) 1,7-dimercapto-4-thioheptane (DMTH-HSCH2CH2CH2SCH2CH 2CH2SH) or 1,2-ethylenediamine (EDA- NH2CH2CH2NH2 ) and triethyltetraamine, TEA (H2NCH2CH2NHCH2CH 2NHCH2CH2 NH2). The characterization of these materials was carried out by TG, IR and TPDMS (Temperature Programmed Decomposition Mass Spectrometry) experiments suggesting the formation of thioesther and amide surface groups, i.e. -COSR and -CONHR, with yields of approximately 50 and 75% for the reaction with DME and EDA, respectively. Preliminary adsorption experiments showed that these materials can efficiently remove metals such as Pb+2, Cu+2 and Ni+2 from aqueous medium.

Fine tuning work function of indium tin oxide by surface molecular design: Enhanced hole injection in organic electroluminescent devices

Characteristics of electroluminescent (EL) devices were improved dramatically using indium tin oxide (ITO) chemically modified with H-, Cl-, and CF3-terminated benzoyl chlorides. By the use of reactive –COCl groups, ITO surfaces were modified quickly and the work function of the modified ITO was changed widely depending upon the permanent dipole moments introduced in the para- position of benzoyl chloride. We also compared the performance of the EL devices with ITO modified with different binding groups (–SO2Cl, –COCl, and –PO2Cl2) of p-chlorobenzene derivatives. Finally, we examined the correlation between the change in the work function and the performance of the EL devices by the chemical modification and found that the enormous increase in ITO work function up to 0.9 eV is possible using phenylphosphoryl dichloride with a CF3-terminal group in the para-position.

Improvement of Power Efficiency in Organic Electroluminescent Devices

ABSTRACTIn order to improve power efficiency of organic electroluminescent (EL) devices, i.e., ITO/TPD/Alq3/Al, enhanced electron and hole injection at Alq3/Al and ITO/TPD interface, respectively, was attempted by designing proper charge injection at both interfaces. Enhanced charge recombination at TPD/Alq3 was also demonstrated. Here, ITO, TPD, Alq3, and Al are abbreviations for indium-tin-oxide, N,N'-diphenyl-N,N'-bis(3-methyl-phenyl)-1,1'-biphenyl-4,4'-diamine, tris(8-hydroxyquinoline) aluminum, and metal aluminum, respectively. Enhanced electron injection by introducing a thin layer of Li salts of fluoride, acetate, and benzoate was described. We have found that the electron injection was improved in the order of Li+, Na+, K+, Rb+, and Cs+, and Cs salts exhibited the best EL performance. Chemical modification of ITO has been attempted to fine-tuning the work function of ITO in order to reduce hole injection barrier height. EL characteristics were improved dramatically using ITO modified with H-, Cl-, and CF3-terminated benzoyl chlorides. By using reactive -COCl groups, ITO surfaces were covered quickly and the work function of ITO was changed widely depending upon permanent dipole moments introduced in para-position of benzoyl chlorides. Correlation between the change in the work function of ITO and the EL characteristics was examined. The improvement of charge recombination was attained by increasing the interfacial areas, i.e. introducing a mixed layer of TPD and Alq3, or inserting a thin film of rubrene with a higher recombination efficiency.

Chemical modification of indium-tin-oxide electrodes by surface molecular design

ABSTRACTIndium-tin-oxide (ITO) is the most widely used material as a transparent electrode due to its excellent transparency and high conductivity. The devices based on bare ITO, however, exhibited inefficient hole injection due to insufficient high work function and required high drive voltages. Thus, various surface treatments of ITO have been attempted to change the work function of ITO in order to reduce the hole injection barrier height. Electroluminescent (EL) characteristics of devices were improved dramatically using ITO chemically modified with H-, Cl-, and CF3-terminated benzoyl chlorides. By the use of reactive -COCl groups, ITO surfaces were modified quickly and the work function of the modified ITO was changed widely depending upon the permanent dipole moments introduced in p-position of benzoyl chloride. We also compared the performance of the EL devices with ITO modified with different binding groups (-SO2Cl, -COCl, and -PO2Cl2) of p-chlorobenzene derivatives. Finally, we examined the correlation between the change in the work function and the performance of the EL devices by the chemical modification and found that the enormous increase in ITO work function up to 0.9 eV is possible using phenylphosphoryl dichloride with a CF3-terminal group in p-position.

Vibrational spectra, thermodynamic functions and barriers to internal rotation for isomeric trifluoromethylbenzoyl chlorides

AbstractThe polarized Raman spectra (50–4000 cm−1) and IR spectra (180–4000 cm−1) of o‐, m‐ and p‐ trifluoromethylbenzoyl chlorides were recorded and all the 45 (30a′ + 15a") normal modes of vibration were assigned assuming Cs symmetry. Consistent assignments for the internal modes of the COCl and CF3 groups are proposed. Thermodynamic functions were computed and barriers to internal rotations for the COCl and CF3 tops were determined, using the assigned vibrational frequencies and assumed structural parameters for the three isomers.

Microwave spectrum and the structure of benzoyl chloride

The microwave spectrum of benzoyl chloride was observed in the frequency range 12–18.6 GHz. Rotational constants have been obtained for the ground vibrational state, the first three excited torsional states of the COCl group, and one of the out-of-plane bending states. The residual inertial defect obtained from the ground and the torsional excited states indicates that the equilibrium conformation is planar. Ab initio MO calculations (STO-3G) showed the potential energy curve as a function of the COCl torsional angle to be rather flat around zero degrees.