Stability Of Copolymers Research Articles

Balancing Electroactive Backbone and Oligo(Ethylene Oxy) Side‐Chain Content Improves Stability and Performance of Soluble PEDOT Copolymers in Organic Electrochemical Transistors

Balancing Electroactive Backbone and Oligo(Ethylene Oxy) Side‐Chain Content Improves Stability and Performance of Soluble PEDOT Copolymers in Organic Electrochemical Transistors

The Spatial Distribution of Lipophilic Cations in Gradient Copolymers Regulates Polymer-pDNA Complexation, Polyplex Aggregation, and Intracellular pDNA Delivery.

Here, we demonstrate that the spatial distribution of lipophilic cations governs the complexation pathways, serum stability, and biological performance of polymer-pDNA complexes (polyplexes). Previous research focused on block/statistical copolymers, whereas gradient copolymers, where the density of lipophilic cations diminishes (gradually or steeply) along polymer backbones, remain underexplored. We engineered gradient copolymers that combine the polyplex colloidal stability of block copolymers with the transfection efficiency of statistical copolymers. We synthesized length- and compositionally equivalent gradient copolymers (G1-G3) along with statistical (S) and block (B) copolymers of 2-(diisopropylamino)ethyl methacrylate and 2-hydroxyethyl methacrylate. We mapped how polymer microstructure governs pDNA loading per polyplex, pDNA conformational changes, and polymer-pDNA binding thermodynamics via static light scattering, circular dichroism spectroscopy, and isothermal titration calorimetry, respectively. While gradient steepness is a powerful design handle to improve polyplex physical properties, augment pDNA delivery capacity, and attenuate polycation-triggered hemolysis, microstructural contrasts did not elicit differences in complement activation.

Core-Shell Structure of Photopolymer-Grafted Polyurethane as a Controlled Drug Delivery Vehicle for Biomedical Application.

Functionalized ultraviolet photocurable bisphenol A-glycerolate dimethacrylates with tailorable size have been synthesized as the core, which have further been grafted using the diisocyanate chain end of polyurethane (PU) as the shell to create a core-shell structure of tunable size for a controlled drug delivery vehicle. The core-shell structure has been elucidated through spectroscopic techniques like 1H NMR, FTIR, and UV-vis and their relative shape and size through TEM and AFM morphology. The greater cross-link density of the core is reflected in the higher glass transition temperature, and the improved thermal stability of the graft copolymer is proven from its thermogravimetric analyses. The flow behavior and enhanced strength of the graft copolymers have been revealed from rheological measurements. The graft copolymer exhibits sustained release of the drug, as compared to pure polyurethane and photopolymer, arising from its core-shell structure and strong interaction between the copolymer and drug, as observed through a significant shifting of absorption peaks in FTIR and UV-vis measurements. Biocompatibility has been tested for the real application of the novel graft copolymer in medical fields, as revealed from MTT assay, cell imaging, and cell adhesion studies. The efficacy of controlled release from a graft copolymer has been verified from the gradual cell killing and ∼70% killing in 3 days vs meager cell killing of ∼25% very quickly in 1 day, followed by the increased cell viability of the system treated with the pure drug. The mechanism of slow and controlled drug release from the core-shell structure has been explored. The fluorescence images support the higher cell-killing efficiency as opposed to a pure drug or a drug embedded in polyurethane. Cells seeded on 3D scaffolds have been developed by embedding a graft copolymer, and fluorescence imaging confirms the successful growth of cells within the scaffold, realizing the potential of the core-shell graft copolymer in the biomedical arena.

An entanglement association polymer electrolyte for Li-metal batteries

To improve the interface stability between Li-rich Mn-based oxide cathodes and electrolytes, it is necessary to develop new polymer electrolytes. Here, we report an entanglement association polymer electrolyte (PVFH-PVCA) based on a poly (vinylidene fluoride-co-hexafluoropropylene) (PVFH) matrix and a copolymer stabilizer (PVCA) prepared from acrylonitrile, maleic anhydride, and vinylene carbonate. The entangled structure of the PVFH-PVCA electrolyte imparts excellent mechanical properties and eliminates the stress arising from dendrite growth during cycling and forms a stable interface layer, enabling Li//Li symmetric cells to cycle steadily for more than 4500 h at 8 mA cm−2. The PVCA acts as a stabilizer to promote the formation of an electrochemically robust cathode–electrolyte interphase. It delivers a high specific capacity and excellent cycling stability with 84.7% capacity retention after 400 cycles. Li1.2Mn0.56Ni0.16Co0.08O2/PVFH-PVCA/Li full cell achieved 125 cycles at 1 C (4.8 V cut-off) with a stable discharge capacity of ~2.5 mAh cm−2.

Effect of chain architecture and comonomer ratio on the biodegradability and thermal stability of biodegradable copolymers of l-lactide and δ-valerolactone

Novel biodegradable copolymers of ʟ-lactide (LA) and δ-valerolactone (VL) were bulk polymerized using stannous octoate as a catalyst initiated with salicylic acid or benzyl alcohol via ring-expansion or ring-opening polymerization, respectively.

Synergistic effect of single wall carbon nanotubes/graphene oxide hybrid nano‐filler on thermal stabilization and tensile strength of polyacrylonitrile copolymer

AbstractThis study reports how hybrid nano‐filler can enhance the tensile strength, electrical properties and thermal stabilization of PAN (polyacrylonitrile) nanocomposite films. The nano‐fillers used are graphene oxide (GO), single‐wall carbon nanotubes (SWCNT), and a hybrid of both. The combination of both nano‐fillers was made by dispersing GO in DMAc (dimethyl acetamide) and then adding SWCNT to the solution. The solution was mixed well using ultrasonication and high‐speed stirring. 1 wt% amount of nano‐filler solutions was added to PAN liquid to make PAN nanocomposite films. The films were tested for mechanical properties, electrical resistivity, thermoxidative stabilization, and thermal stability. The results showed that adding nano‐fillers to PAN significantly improved its tensile strength. GO increased the tensile strength by 42.9% (38.3 MPa), while SWCNT increased it by 57.3% (42.15 MPa). The combination of both (0.5 wt% SWCNT + 0.5 wt% GO) had a remarkable effect, increasing the tensile strength by 96% (52.53 MPa). This was because the combination of both prevented SWCNT from agglomerating together and made it interact better with the PAN, forming a complete network. The combination of both also made the PAN oxidize and stabilize early and efficiently during heating, which made its residual weight increase by ~5.5% more than pristine PAN in TGA. The electrical resistivity and SEM micrograph data correlate with the thermal analysis data, showing that PCG (1 wt% combination) reached the percolation threshold because of the benefits of both GO and SWCNT. The combination of both also showed 95.6% synergy in tensile strength compared to individual nano‐fillers, indicating its potential for efficient reinforcement.Highlights Hybrid filler boosts PAN strength from 26.8 to 52.53 MPa, surpassing PC, PG. TGA: ~5.5 wt% increased residual weight in 1 wt% hybrid‐reinforced PCG composites. Hybrid undergoes GO decomposition, early oxidation and improved stabilization. PCG composite: Enhanced oxidation, improved stabilization via SWCNT network. PC & PCG composites show low volumetric resistivity due to SWCNT network.

Terpolymers of acrylonitrile, methyl acrylate, and 2‐acrylamido‐2‐methylpropane sulfonic acid for carbon fiber precursor: Effect of comonomers on the thermal stabilization of polyacrylonitrile copolymers

AbstractPolyacrylonitrile (PAN) copolymers are important precursors for the preparation of high‐performance PAN‐based carbon fibers. In this study, different ratios of P(AN‐co‐AMPS) and P(AN‐co‐MA‐co‐AMPS) were prepared by solution polymerization. The compositional structure, thermal, and crystallization properties of P(AN‐co‐AMPS) and P(AN‐co‐MA‐co‐AMPS) were characterized. The results show that an increase in the AMPS feeding ratio is beneficial for improving the thermal stability and crystallization ability of the PAN copolymer; however, it also reduces the molecular weight of the copolymer and increases the cyclization exothermic peak temperature, which is not conducive to the preparation of high‐performance carbon fibers. This problem is avoided in P(AN‐co‐MA‐co‐AMPS), which maintains its high thermal stability and crystallization properties when appropriate amounts of MA and AMPS are introduced, and P(AN‐co‐MA‐co‐AMPS) has smoother cyclization exothermic rates, lower onset exothermic temperatures and lower peak exothermic temperatures. The structural changes of PAN, P(AN‐co‐MA), and P(AN‐co‐MA‐co‐AMPS) during thermal stabilization were investigated in detail using Fourier‐transform infrared spectroscopy and it was found that P(AN‐co‐MA‐co‐AMPS) formed more stable structures at lower temperatures. Furthermore, when the AN:MA:AMPS mass ratio is 97.5:1.5:1, P(AN‐co‐MA‐co‐AMPS) has the best overall performance. Our results suggest that the P(AN‐co‐MA‐co‐AMPS) has potential as a precursor for carbon fibers.

19 nm‐Thick Grafted‐To Polymer Brushes onto Optimized Poly(Dopamine)‐Coated Surfaces

AbstractGrafting‐to polymer coatings are typically easy to apply, but the thickness of such coatings is typically limited to a few nanometers, which may hamper applications. This paper presents a grafting‐to coating approach that yields polymer brushes up to an unprecedented thickness of 19 nm. To this aim, an easy‐to‐apply poly(dopamine) (PDA) primer layer is optimized. PDA is an easy‐to‐apply, but highly complex and chemically not well understood primer layer. In this study, PDA is deposited on silicon substrates using several deposition protocols (pH 4–7 in presence of NaIO4, and from Tris solution at pH 8.5). The modified surfaces are characterized using X‐ray photoelectron spectroscopy, spectroscopic ellipsometry, static water contact angle measurements, and atomic force microscopy. Subsequently, block copolymers of poly(glycidyl methacrylate)20‐b‐poly(N‐isopropylacrylamide)n are attached onto the PDA films using a grafting‐to approach. The results indicate that the conditions of PDA deposition and the PDA film thickness strongly influence the stability and grafting efficiency of the block copolymers. PDA films deposited at pH 7 with NaIO4 are stable, and yield the most efficient grafting, with grafted polymer layers as thick as 19 nm. Polymer layers of such thickness are rarely achieved using grafting‐to procedures from solution.

Synthesis and rheological properties of water soluble ionic copolymers as modifier fluids at high temperature and saline media

AbstractPolymer flooding depicts an interesting strategy to improve the enhanced oil recovery (EOR). This work aims with the synthesis of ionic thermo‐responsive copolymers able to be used as rheological modifiers for EOR under harsh conditions (250,000 ppm of NaCl at 150°C). Copolymers composed of different molar ratio of acrylamide, N‐isopropylacrylamide and 2‐acrylamide‐2‐methyl‐1‐propanesulfonic acid were prepared in aqueous media via free radical polymerization at 50°C using 4,4′‐azobis(‐4″‐cyanopentanoic) acid (ACPA) as initiator. Nuclear magnetic resonance analyses demonstrated the structure and molar composition of synthesized copolymers. Rheological measurements performed at different concentration from 1 to 8 wt% demonstrated an increase in the viscosity from 2000 to 600,000 mPa.s. Aqueous mixtures of polymer at 5 wt% and NaCl at different concentration (5, 10, 15, 20, and 25 wt%) was analyzed. Copolymer ([PAM]/[PNIPAM] = 50/50) displayed a phase separation at 15 wt% of NaCl. Solutions of polymer at 5 and 25 wt% of NaCl were heated at 150°C for 72 h. Results revealed both thermal stability and saline tolerance of copolymers [PAM]/[PNIPAM]/[PAMPS‐Na] = 25/25/50, 35/35/30, and 50/0/50 under harsh conditions with the absence of phase separation of the brine polymer solutions.

ТЕРМООКИСЛИТЕЛЬНАЯ УСТОЙЧИВОСТЬ ПРОТОНООБМЕННЫХ МЕМБРАН НА ОСНОВЕ СОПОЛИМЕРОВ СТИРОЛСУЛЬФОКИСЛОТЫ И N-ВИНИЛИМИДАЗОЛА

The differential scanning colorimetry (DSC) thermooxidative stability of new copolymers of styrene-sulfonic acid and N-vinylimidazole obtained by radical copolymerization in a DMF solution in an argon atmosphere has been studied

Methacrylic acid‐based amphiphilic block‐random copolymer stabilizers for emulsion polymerization

AbstractThe emulsion polymerization of styrene was investigated using polystyrene‐b‐[polystyrene‐r‐poly(methacrylic acid)] amphiphilic block‐random copolymers (BRCs) of different compositions as stabilizers. These stabilizers with molar masses <20,000 g/mol, which possess unique dispersion behaviour (i.e., self‐assembly with low aggregation numbers) when dissolved in aqueous medium at alkaline pH, were prepared by the nitroxide‐mediated bulk polymerization of styrene to achieve a desired molar mass followed by chain extension by batchwise addition of styrene and methacrylic acid monomers to obtain the stabilizing group. Emulsion polymerizations of styrene stabilized by these BRCs yielded stable latexes with particle diameters that range between 30 and 150 nm. When different concentrations of the stabilizer (2–3.5 mM) were utilized for emulsion polymerization of styrene, a similar novel emulsion polymerization mechanism observed previously by our group for the acrylic‐acid based amphiphilic BRCs was also seen, further validating the difference between this class of polymeric surfactants and conventional small molecule surfactants, block copolymers, or alkali soluble resins. The performance of methacrylic‐acid based BRCs was more efficient and yielded higher surface coverage of the polystyrene latexes when compared to the acrylic‐acid based BRCs as a result of the more hydrophobic nature of the former.

Application of vinyl acrylic co-polymer on subgrade and sub base pavement stabilization

A typical method for improving the tensile strength, durability, and swell-shrink behavior of subgrade soil in the pavement is soil stabilization. Numerous researchers have tried a variety of techniques to stabilize the soil. The use of polymer stabilizers has increased, much like other stabilizers. The vinyl-based co-polymer is used in asphalt admixtures, concrete building, dust management, and soil stabilization for highways. Additionally, considering the challenges of the expensive and shortage of stone aggregate in many regions of the country, using locally accessible brick aggregate (i.e over burnt brick aggregate) for sub-base course can be a viable and more affordable solution. The properties of stabilized soil and soil-aggregate combinations were determined at 7 days after cure using the vinyl acrylic co-polymer (K31-APS). By dry weight of the soil and soil-aggregate combination, the vinyl acrylic co-polymer (K31-APS) was added in the ratio of 1:6 (1 part of K31 and 6 parts of water). A combination of soil and aggregate was used in various ratios: 0%, 25%, 50%, and 75%. Laboratory tests such as the unconfined compressive strength and california bearing ratio tests were carried out. Also, scanning electron microscopy test was performed to study the microstructure of the samples. The results showed that adding vinyl acrylic co-polymer to the soil and soil-aggregate combination had no significant changes on maximum dry density but improved the CBR, UCS, and Mr values of the subgrade and sub-base pavement layers in comparison to the unmodified pavement layers. When compared to the unmodified sample, the strength of the soil increased by 94%, while the strength of the soil-aggregate mixture increased by 179%. In contrast, the strength improvements for mixtures of 25% soil and 75% aggregate and 75% soil and 25% aggregate were 50% and 66%, respectively. The addition of vinyl acrylic co-polymer minimizes the thickness of the pavement layers and the cost savings of treated soil-aggregate mixture were found to be 21.63%, 4.77% and 11.02% as compared to untreated sample. Without adding any cementitious material, vinyl acrylic co-polymer (K31-APS) can improve the pavement property with minimum expenses. Consequently, stabilizing the pavement layers with vinyl acrylic co-polymer (K31-APS) stabilizer may be a practical method for constructing roads in a sustainable manner.

Evaluating the in vivo stability of water-soluble PEG-PLA copolymers using FRET imaging

Biodegradable and biocompatible polymer materials with tunable physical properties present a great interest for controlled drug delivery applications. A good example is BEPO®, a clinical-stage in situ-forming depot technology based on the utilization of a blend of poly(ethylene glycol)-b-poly(D,L-lactic acid) (PEG-PLA) diblock and triblock amphiphilic copolymers dissolved in an organic solvent. Once injected, this technology will form a bioresorbable solid polymer depot that will allow the release of a drug from weeks to months. The safety of the final degradation products from this technology, i.e., PEG and lactic acid, is well-documented. However, little information exists about the fate of intermediate degradants, specifically of water-soluble PEG-PLA chains where the molecular weights of the PLA block are short. Herein, we designed a Förster Resonance Energy Transfer (FRET) system for short copolymers, suitable for longitudinal in vivo imaging in the subcutaneous space, allowing to follow the stability of these products. Our results confirm that these species, that might be leaked from BEPO® depots during degradation, are rapidly hydrolyzed in the subcutaneous space of mice, forming approved products by Health Authorities, i.e., PEG and PLA homopolymers and/or lactic acid.

Adsorption of radioactive cesium using synthesized chitosan-g-poly(acrylic acid/N-vinylcaprolactam) by γ-irradiation

To remove radioactive cesium ions from wastewater, graft copolymer of chitosan-g-poly(acrylic acid/N-vinylcaprolactam) [CTS-P(AA/VC)] was synthesized. The shape, thermal stability, and structure of the graft copolymer were all successfully characterized by SEM, TGA, and FT-IR. Batch sorption experiments were carried out in order to evaluate the effects of various parameters such as pH, contact time, adsorbate initial concentration, and temperature. The kinetics data of batch interaction were also extensively covered with various (linear and non-linear) models of sorption kinetic such as pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. Langmuir and Freundrich equations isotherm models were studied by linear and non-linear equations. To determine the best-fitting equations, the correlation coefficient (R2) and the normalized standard deviation Δq (%) were used as error analysis methods. It appeared briefly that the linear and non-linear forms of pseudo-second order and the Langmuir model are better fitted for kinetic and isotherm models, respectively. The elimination capability for cesium-134 radionuclides was ∼115 mg g-1. Thermodynamic parameters showed exothermic, spontaneous nature and decreased randomness during the adsorption process. After the adsorption studies, the elution process was successfully proceeds by using different eluting agents. The findings suggested that CTS-P(AA/VC) graft copolymer could be a useful material for treating cesium-134 ions-containing liquids.

Construction of Fluorescent Conjugated Polytriazole Containing Double-Decker Silsesquioxane: Click Polymerization and Thermal Stability.

This study synthesized two azide-functionalized monomers through p-dichloro xylene and double-decker silsesquioxane (DDSQ) units with NaN3 to form DB-N3 and DDSQ-N3 monomers, respectively. In addition, five different propargyl-functionalized monomers were also prepared from hydroquinone, bisphenol A, bis(4-hydroxyphenyl)methanone, 2,4-dihydroxybenzaldehyde (then reacted with hydrazine hydrate solution) and 1,2-bis(4-hydroxyphenyl)-1,2-diphenylethene with propargyl bromide to form P-B, P-BPA, P-CO, P-NP, and P-TPE monomers, respectively. As a result, various DDSQ-based main chain copolymers could be synthesized using Cu(I)-catalyzed click polymerization through DDSQ-N3 with different propargyl-functionalized monomers, of which the chemical structure and molecular weight could be confirmed by using Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC) analyses. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscope (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy analyses also could characterize the thermal stability, morphology, and optical behaviors of these DDSQ-based copolymers. All results indicate that the incorporation of an inorganic DDSQ cage could improve the thermal stability such as thermal decomposition temperature and char yield, because of the DDSQ dispersion homogeneously in the copolymer matrix, and this would then affect the optical properties of NP and TPE units in this work.

Solution and Solid-State Behavior of Amphiphilic ABA Triblock Copolymers of Poly(acrylic acid-stat-styrene)-block-poly(butyl acrylate)-block-poly(acrylic acid-stat-styrene)

A combination of statistical and triblock copolymer properties is explored to produce stable aqueous polymer dispersions suitable for the film formation. In order to perform an extensive structural characterization of the products in the dissolved, dispersed, and solid states, a wide range of symmetrical poly(acrylic acid-stat-styrene) x -block-poly(butyl acrylate) y -block-poly(acrylic acid-stat-styrene) x , poly(AA-st-St) x -b-PBA y -b-poly(AA-st-St) x , (x = 56, 108 and 140, y = 100-750; the AA:St molar ratio is 42:58) triblock copolymers were synthesized by reversible addition-fragmentation chain transfer (RAFT) solution polymerization using a bifunctional symmetrical RAFT agent. It is demonstrated that the amphiphilic statistical outer blocks can provide sufficient stabilization to largely hydrophobic particles in aqueous dispersions. Such a molecular design provides an advantage over copolymers composed only of homoblocks, as a simple variation of the statistical block component ratio provides an efficient way to control the hydrophilicity of the stabilizer block, which ultimately affects the copolymer morphology in solutions and solid films. It was found by small-angle X-ray scattering (SAXS) that the copolymers behaved as dissolved chains in methylethylketone (MEK) but self-assembled in water into stable and well-defined spherical particles that increased in size with the length of the hydrophobic PBA block. These particles possessed an additional particulate surface structure formed by the statistical copolymer stabilizer block, which self-folded through the hydrophobic interactions between the styrene units. SAXS and atomic force microscopy showed that the copolymer films cast from the MEK solutions formed structures predicted by self-consistent field theory for symmetrical triblock copolymers, while the aqueous dispersions formed structural morphologies similar to a close-packed spheres, as would be expected for copolymer particles trapped kinetically due to the restricted movement of the blocks in the initial aqueous dispersion. A strong correlation between the structural morphology and mechanical properties of the films was observed. It was found that the properties of the solvent cast films were highly dependent on the ratios of the hard [poly(AA-st-St)] and soft (PBA) blocks, while the aqueous cast films did not show such a dependence. The continuous phase of hard blocks, always formed in the case of the aqueous cast films, produced films with a higher elastic modulus and a lower extension-to-break in a comparison with the solvent-cast films.

Preparation A Cross-Linked Copolymer By Using Unsaturated Poly(2-Butene Maleate) Polyester and Methyl Methacrylate

In this study, synthesis of unsaturated Poly(2-Butene Maleate) polyester by condensation polymerization and preparation of cross-linked graft copolymer with methyl methacrylate are presented. For this purpose, unsaturated polyesters were synthesized in four different time periods (12h, 24h, 36h, 48h) in the presence of hydroquinone using 1,4-Butanediol-2-ene and maleic anhydride. Then, the obtained unsaturated polyester was purified on the alumina column and used to obtain cross-linked copolymer with methyl methacrylate. Here in, methyl methacrylate acts as both co-monomer and cross-linking agent.
 In the preparation of Poly(2-Butene Maleate), the optimization study of the molecular weight and yield ratios with the time parameter was carried out. In the results obtained, it was observed that the maximum molecular weight was reached after almost 36 hours (Mn=3400). It was observed that time did not have much effect on the yield. Structural characterizations of the obtained products were supported by FT-IR and NMR analyzes. In thermal analysis, it was observed that the thermal stability of Cross-linked graft copolymer is higher than unsaturated polyester but lower than pure Poly(methyl methacrylate).

Simultaneously Improving Flame Retardant Performance, Thermal Stability and Conductivity of Copolymers of Polyethylene‐octene by Addition of a Ternary Composite Flame Retardant System

AbstractThe development of high efficiency and low‐cost refractories has always been a subject that attract people‘s attention. Although polyethylene‐octene copolymers (POE) has excellent mechanical properties, it is easy to be ignited, which seriously hinders its multi‐field applications. In this paper, a novel ternary composite flame retardant system, ammonium polyphosphate (APP)/expanded graphite (EG)/sepiolite (SEP), was proposed and applied to POE to prepare high flame‐retardant POE composites. The experimental results showed that the addition of SEP could play a good reinforcing role, so as to improve the mechanical properties of POE/APP composites. Thermogravimetric analysis (TGA) showed that when the ratio of EG and SEP was 1 : 1, the initial thermal decomposition temperature decreased significantly, which was conducive to the early degradation and carbonization of POE/APP composites. The thermal conductivity test showed that the addition of SEP can reduce the thermal conductivity of POE/APP composites. In addition, the flame retardant test results revealed that when the ratio of EG and SEP was 1 : 1, the oxygen index (LOI) increased to 25.3 %, the heat release rate (HRR) decreased to 140 kW/m2, the total heat release (THR) decreased to 70 MJ/m2, and the carbon layer produced by combustion was dense and uniform, which contribute to the great heat insulation. In conclusion, the addition of an appropriate amount of ternary compound flame retardant (EG/SEP/APP) could have an excellent synergistic flame retardant effect on POE/APP composites, and the processing method was simple and efficient, which would benefit to broad application of the prepared POE composites.

Removal of anionic and cationic dyes using porous copolymer networks made from a Sonogashira cross‐coupling reaction of diethynyl iron (II) clathrochelate with various arylamines

AbstractFour copolymers containing alternating units of iron(II) clathrochelate with various arylamine CLA1‐4 were synthesized via a palladium‐catalyzed Sonogashira cross‐coupling reaction using an iron(II) clathrochelate synthon end‐capped with ethynyl groups with various brominated arylamine derivatives. Target copolymers CLA1‐4 were characterized by various instrumental analysis techniques, such as, solid‐state 13C‐nuclear magnetic resonance (SSNMR), Fourier transform infrared (FTIR), and X‐ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) disclosed the superior thermal stability of the target copolymers with 10% weight loss temperature values up to ~340°C. Nitrogen adsorption measurements of CLA1‐4 using Brunauer–Emmet–Teller (BET) model revealed their porous nature with a surface area and porosity up to ~411 m2 g−1 and 0.411 cm3 g−1, respectively. Interestingly, CLA1‐4 disclose efficient adsorption of both cationic and anionic organic dyes, such as, Methylene Blue (MEB), Rhodamine B (RB), Congo Red (CR), Methyl orange (MO), and Acid orange 7 (AO7) from aqueous solutions. Furthermore, the isothermal adsorption study divulges the CLA4 uptake from aqueous solution of MEB and CR following the Langmuir model with a maximum adsorption capacity (qm) of 146.63 mg g−1 and 787.40 mg g−1, respectively.

Synthesis and characteristics of nonisocyanate polyurethane composed of bio‐based dimer diamine for supercritical CO2 foaming applications

AbstractNonisocyanate polyurethane (NIPU) was synthesized using different concentrations of C36‐alkylenediamine (C36DDA), hexamethylene diamine, and a cyclic carbonate monomer synthesized from bisphenol A epoxy resin and carbon dioxide. The structures, molecular weights, thermal behaviors, and stabilities of the NIPU copolymers were evaluated using 1H nuclear magnetic resonance, Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry measurements. All synthesized NIPUs were amorphous and exhibited good Td−5% thermal stabilities above 250°C; Tg decreased from 73 to 51°C as C36DDA content increased from 0% to 10% based on dynamic mechanical analysis tests. Furthermore, ethylenediamine (EDA) as a chain extender incorporating a small amount of crosslinker 1,2,4,5‐benzenetetracarboxylic acid (PMA) can enhance the melt strength of a partially three‐dimensional network, and the attained NIPU showed elastic properties. Thus, the NIPU synthesized with 7.5% and 10% C36DDA containing small amounts of EDA and PMA were suitable choices for supercritical CO2 foaming; their morphologies and mechanical behaviors were examined by scanning electron microscopy and DMA, and the densities of foamed NIPU with 7.5% and 10% C36DDA were calculated as 432 and 215 kg m−3 with pore sizes of 10–20 μm, respectively. The maximum stresses were attained at 149.5 and 123.4 kPa, and the foamed NIPU displayed rigid foam behaviors owing to the compression behaviors of the stress–strain curves.