Diethyl Acrylamide Research Articles

Synthesized Crosslinking Suspension Stabilizer for Spacer Fluid in High-Temperature Conditions: Synthesis, Behavior, and Mechanism Research

Summary High-temperature stability of spacer fluid is a vital prerequisite to ensure the safety of cementing operations in deep or ultradeep wells. Faced with this problem, the thermal stability of the suspension agent in the spacer fluid at high temperatures is improved from the aspects of polymerization monomer and molecular chain. A terpolymer SAD was synthesized by free radical polymerization of sodium styrene sulfonate (SSS), acrylamide (AM), and N, N’-diethylacrylamide (DEAA) in aqueous solution. The name of the terpolymer, SAD, is the initial letter composition of the three polymerization monomers. Polyethyleneimine (PEI) can improve the molecular chain structure of SAD by transamidation reaction with the amide group in SAD, so a high temperature suspension agent PSAD (polyethyleneimine + SAD) was obtained by compounding PEI with SAD. The structure and properties of PSAD were characterized by Fourier infrared spectroscopy, hydrogen nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, scanning electron microscopy (SEM), and viscosity test. In addition, the comprehensive properties of the spacer fluid under the action of PSAD are evaluated. The results showed that the crosslinking degree of PSAD gradually increased with the increase in temperature. After aging at 200°C, the decomposition temperature of PSAD was 305°C, which show terrific thermal stability. At the same time, the spacer fluid prepared by PSAD not only has excellent rheological properties in the range of 90 ~ 200°C but also keeps the density difference between the upper and lower parts of the slurry less than 0.02 g/cm3 and the filtration loss of the slurry less than 50 mL.

Application of Thermoresponsive Smart Polymers based in situ Gel as a Novel Carrier for Tumor Targeting.

The temperature-triggered in situ gelling system has been revolutionized by introducing an intelligent polymeric system. Temperature-triggered polymer solutions are initially in a sol state and then undergo a phase transition to form a gel at body temperature due to various parameters like pH, temperature, and so on. These smart polymers offer a number of advantages, including ease of administration, long duration of release of the drug, low administration frequency with good patient compliance, and targeted drug delivery with fewer adverse effects. Polymers such as poly(N-isopropylacrylamide) (PNIPAAm), polyethylene glycol (PEG), poly (N, N'-diethyl acrylamide), and polyoxypropylene (PPO) have been briefly discussed. In addition to various novel Drug Delivery Systems (DDS), the smart temperature-triggered polymeric system has various applications in cancer therapy and many other disease conditions. This review focuses on the principals involved in situ gelling systems using various temperature-triggered polymers for chemotherapeutic purposes, using smart DDS, and their advanced application in cancer therapy, as well as available marketed formulations and recent advances in these thermoresponsive sol-gel transforming systems.

Thermo‐Responsive Ultrafiltration Block Copolymer Membranes Based on Polystyrene‐block‐poly(diethyl acrylamide)

Thermo‐Responsive Ultrafiltration Block Copolymer Membranes Based on Polystyrene‐<i>block</i>‐poly(diethyl acrylamide)

Characterization and swelling behavior of hydrogels from N-isopropylacrylamide, N,N′-diethylacrylamide, acrylic acid, and its use for drug release

Here, a series of semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized and investigated by combining three materials such as N-isopropylacrylamide (NIPAM), N,N′-diethylacrylamide (DEA), and acrylic acid (AAc). The linear copolymer p(NIPAM-co-AAc) was introduced into DEA solution in the presence of N,N′-methylenebisacrylamide to synthesize p(NIPAM-co-AAc)/pDEA semi-IPN hydrogels using free radical polymerization. Scanning electron microscope images demonstrated the porous morphology of hydrogels with pore sizes in the range of 220–969 µm. The physicochemical properties of polymers were evaluated by various characterization techniques, including gel permeation chromatography, dynamic light scattering, differential scanning calorimetry, rheological measurement, mechanical properties, and swelling behaviors. The results indicated that the introduction of linear copolymers into conventional hydrogels has significantly improved the properties of the hydrogels. Besides, the use of NIPAM has significantly improved the thermal sensitivity of the polymers in this work. Finally, a selected semi-IPN hydrogel was evaluated for its potential for the drug release of paracetamol. The sorption of paracetamol was an exothermic process that obeyed the Freundlich isotherms, with the highest sorption of 119.57 mg/g. The paracetamol release followed the Korsmeyer–Peppas model and was consistent with the Fickian diffusion mechanism.

Thermo‐Responsive Ultrafiltration Block Copolymer Membranes Based on Polystyrene‐block‐poly(diethyl acrylamide)

AbstractWithin the present work, a thermo‐responsive ultrafiltration membrane is manufactured based on a polystyrene‐block‐poly(diethyl acrylamide) block copolymer (BCP). The poly(diethyl acrylamide) block segment features a lower critical solution temperature (LCST) in water, similar to the well‐known poly(N‐isopropylacrylamide), but having increased biocompatibility and without exhibiting a hysteresis of the thermally induced switching behavior. The BCP is synthesized via sequential “living” anionic polymerization protocols and analyzed by 1H‐NMR spectroscopy, size exclusion chromatography, and differential scanning calorimetry. The resulting morphology in the bulk state is investigated by transmission electron microscopy (TEM) and small‐angle X‐ray scattering (SAXS) revealing the intended hexagonal cylindrical morphology. The BCPs form micelles in a binary mixture of tetrahydrofuran and dimethylformamide, where BCP composition and solvent affinities are discussed in light of the expected structure of these micelles and the resulting BCP membrane formation. The membranes are manufactured using the non‐solvent induced phase separation (NIPS) process and are characterized via scanning electron microscopy (SEM) and water permeation measurements. The latter are carried out at room temperature and at 50 °C revealing up to a 23‐fold increase of the permeance, when crossing the LCST of the poly(diethyl acrylamide) block segment in water.

High-Speed Synthesis of Thermo-responsive Polymers by Boosted Polymerization of N,N-Diethyl Acrylamide in High-Temperature Water

High-Speed Synthesis of Thermo-responsive Polymers by Boosted Polymerization of <i>N</i>,<i>N</i>-Diethyl Acrylamide in High-Temperature Water

Preparation of Magnetic Temperature-Sensitive Polymer Composite Carrier and Study on Immobilized Penicillin G Acylase

This work designed and prepared a novel type of carrier for immobilization of penicillin G acylase (PGA), and then the performances of the immobilized PGA were studied in detail. The process is presented as follows: First, dopamine (DA), an adhesive biological secondary metabolite, was adopted to form a polydopamine (PDA) coating on the surface of Fe3O4nanoparticles (NPs) prepared by the inverse microemulsion method to generate Fe3O4@PDA NPs through in-situ polymerization. After that, the obtained Fe3O4@PDA NPs were modified by reversible addition fragmentation chain transfer (RAFT) reagent containing carboxyl groups on its surface. Then, taking N,N diethyl acrylamide (DEA) as the temperature-sensitive monomer, [Formula: see text]-hydroxyethyl methacrylate (HEMA) as the hydrophilic monomer, glycidyl methacrylate (GMA) as the target monomer and methyl methacrylate (MMA) as the monomer controlling the distance between targets, through the “Grafting from” strategy and the RAFT polymerization method, the magnetic temperature-sensitive polymer composite, Fe3O4@PDA-g-PDEA-b-PHEMA-b-P(MMA-co-GMA) NPs with different feeding ratios of MMA/GMA, was prepared to realize the immobilization of penicillin G acylase (PGA). Based on samples prepared at each stage of the carrier, the structure and performances were characterized by Fourier Infrared Spectroscopy (FTIR), Transmission Electron Microscope (TEM), X-ray Diffraction (XRD), and Vibration Specimen Magnetometer (VSM), respectively. Besides, the content of RAFT graft Fe3O4@PDA was also quantitatively characterized by ICP, and the molecular weight of the polymer was characterized by mass spectrometry. Result showed that the target space influenced enzyme load capacity (ELC), enzyme activity (EA) and enzyme activity recovery rate (EAR) at a large degree, and there was no positive relationship between ELC to EA and EAR. Last, performances of the immobilized PGA, including relative enzyme activity ([Formula: see text]) of immobilized PGA, were 83.9% after storing for 90 days, and 90.3% of the initial activities were still retained after 12 times of repeated use, and the catalytic stability (temperature, pH) and Michaelis–Menten const [Formula: see text] were investigated with free PGA as control if operation was allowed.

Lewis Pair Radical Polymerization “On-Water”

An unprecedented radical polymerization of various (meth)acrylates, diethyl acrylamide, and 4-vinylpyridine initiated by Lewis pair (LP) catalysts, specifically PPh3/Cu(OTf)2 or PPh3/Sn(OTf)2, is reported herein. The reaction occurred at the interface between monomer and water phases, namely, “on-water”, at room temperature. The polymerization of (meth)acrylates “on-water” was significantly more efficient than the reaction in organic solvents or in bulk. It was determined that the propagation occurs via a single electron transfer, which was evidenced by the inhibition of the reaction by the addition of trace amounts of phenols or phenothiazine. Additionally, MALDI-TOF-MS analysis revealed the occurrence of disproportionation termination. Initiation at the interface was supported by various polymerization studies. Specifically, a higher rate of polymerization of methacrylates was observed for hydrophilic monomers. Moreover, the polymerizations in a mixed solvent of water and MeOH indicated that the heterogeneous system is critical. The generation of a PPh3 radical cation following a single electron transfer from LP was not plausible. Instead, we propose a mechanism involving a Michael addition of PPh3 to monomers activated by Lewis acids “on-water” to generate Cu(II) or Sn(II) enolates and/or free radical as propagating species.

Multiparameter evaluation of acrylamide HEMA alternative monomers in 2-step adhesives

ObjectiveAs frequently added to adhesives, the mono-functional monomer 2-hydroxyethyl methacrylate (HEMA) acts as co-solvent and improves surface wetting. Nevertheless, HEMA promotes watersorption and hydrolysis at adhesive interfaces, affecting bond durability to dentin. This study investigated if two acrylamide co-monomer alternatives could replace HEMA in experimental adhesive-resin formulations as part of 3/2-step universal adhesives applied, respectively, in etch-and-rinse (E&R) and self-etch (SE) bonding modes. MethodsUpon priming dentin with the 10-MDP-based Clearfil SE Bond 2’ primer (‘C-SE2p’; Kuraray Noritake), three experimental adhesive resins, consisting of 50 wt.% Bis-GMA, 15 wt.% TEGDMA, and either 35 wt.% diethyl acrylamide (‘DEAA’), hydroxyethyl acrylamide (‘HEAA’) or HEMA (‘HEMA+’), were applied. The control HEMA-free adhesive resin contained 60 wt.% Bis-GMA and 40 wt.% TEGDMA (‘HEMA−’). All adhesives were evaluated for ‘immediate’ and ‘aged’ micro-tensile bond strength (μTBS) to dentin upon, respectively, 1-week (1w) and 6-month (6m) water storage, TEM adhesive-dentin interfacial interaction, 24-h and 6m three-point bending, contact-angle wetting, viscosity and watersorption. ResultsLinear mixed-effects model statistics revealed significantly better bonding performance of the adhesives applied in E&R than SE mode, except for DEAA_1w, with the highest μTBSs recorded for DEAA and HEMA− applied in SE mode. In E&R mode, aging did not significantly reduce DEAA’s μTBS. Best wetting on primed dentin was recorded for HEMA+, significantly better than DEAA, further HEAA and HEMA−, these directly related to their viscosity. HEAA absorbed significantly more water than all other adhesive-resin formulations. HEMA−>DEAA>HEAA>HEMA+ was the significant order for 6m bending strength. ConclusionsThe acrylamide co-monomer DEAA could replace HEMA, while HEAA not.

Synthesis and Properties of pH-Thermo Dual Responsive Semi-IPN Hydrogels Based on N,N'-Diethylacrylamide and Itaconamic Acid.

A series of semi-interpenetrating polymer network (semi-IPN) hydrogels based on N,N’-diethylacrylamide (DEA) and itaconamic acid (IAM) were synthesized by changing the molar ratio of linear copolymer P(DEA-co-IAM) and DEA monomer. Linear copolymer P(DEA-co-IAM) was introduced into a solution of DEA monomer to prepare pH-thermo dual responsive P(DEA-co-IAM)/PDEA semi-IPN hydrogels. The thermal gravimetric analysis (TGA) revealed that the semi-IPN hydrogel has a higher thermal stability than the conventional hydrogel, while the interior morphology by scanning electron microscopy (SEM) showed a porous structure with the pore sizes could be controlled by changing the ratio of linear copolymer in the obtained hydrogels. The oscillatory parallel-plate rheological measurements and compression tests demonstrated a viscoelastic behavior and superior mechanical properties of the semi-IPN hydrogels. Besides, the lower critical solution temperature (LCST) of the linear copolymers increased with the increase of IAM content in the feed, while the semi-IPN hydrogels increased LCSTs with the increase of linear copolymer content introduced. The pH-thermo dual responsive of the hydrogels was investigated using the swelling behavior in various pH and temperature conditions. Finally, the swelling and deswelling rate of the hydrogels were also studied. The results indicated that the pH-thermo dual responsive semi-IPN hydrogels were synthesized successfully and may be a potential material for biomedical, drug delivery or absorption applications. The further applications of semi-IPN hydrogels are being conducted.

Multi-Switchable Bioelectrocatalysis Based on Semi-Interpenetrating Polymer Network Films Prepared by Enzyme-Induced Polymerization

The polymerization of N,N′-diethylacrylamide (DEA) into PDEA hydrogels could be initiated by glucose oxidase (GOD) in the presence of glucose, Fe2+ and oxygen. Based on this, the semi-interpenetrating polymer network (semi-IPN) films containing PDEA, hyaluronic acid (HA) and GOD were prepared on electrode surface. The electroactive probe ferrocenedicarboxylic acid (Fc(COOH)2) in solution demonstrated reversible pH-, temperature- and SO42−-sensitive cyclic voltammetric (CV) on-off behavior at the film electrodes. Taking pH-responsive property of the system as an example, at pH 4.5, the probe showed a large and well-defined CV peak pair, and the system was at the on state; while at pH 8.0, the CV peaks were greatly suppressed and the system was at the off state. The system could be further used to switch the electrochemical oxidation of glucose catalyzed by GOD in the films and mediated by Fc(COOH)2 in solution with pH, temperature and SO42− as the stimuli. Herein the enzyme GOD functioned in two ways: (1) in preparation of the films, GOD could induce radical polymerization of PDEA; (2) in the following electrochemical studies, GOD could catalyze the oxidation of glucose and helped to realize the switchable bioelectrocatalysis with amplification effect.

Thermo-responsive, UV-active poly(phenyl acrylate)-b-poly(diethyl acrylamide) block copolymers

The homopolyinerization of phenyl acrylate (PA) was investigated for the first time by nitroxide mediated polymerization (NMP) with the succinimidyl form of the SG-1-based unimolecular initiator 24N-tert-butyl-2,2-(dimethylpropy1)-aminooxy]propionic acid (BlocBuilder MA). The control of PPA hoinopolymerization was improved by the use of 15 mot% additional free nitroxide SG1 atert-butyl[1-(diethoxyphospholy1)-2,2-dimethylpropyl]amino]oxidanyl) and dispersities, M-w/M-n of around 1.2 were achieved. A PPA homopolyiner was then successfully chain-extended with diethyl acrylainide (DEAAin) to form a block copolyiner of PPA-b-PDEAAm where the PDEAAm segment is therino-responsive, while the PPA block is potentially UV-active. The thermo-responsive behavior of the block copolymer in 0.5 we/) aqueous solution was studied by UV-Vis spectrometry and dynamic light scattering (DLS), indicating cloud point temperatures of 26-30 degrees C, close to that reported for PDEAAm homopolymers.

Toward Copolymers with Ideal Thermosensitivity: Solution Properties of Linear, Well-Defined Polymers of N-Isopropyl Acrylamide and N,N-Diethyl Acrylamide

Statistical copolymers of N-isopropyl acrylamide (NIPAM) and N,N-diethyl acrylamide (DEAAM) show a pronounced synergistic depression in their cloud points, though both homopolymers phase separate at significantly higher temperatures close to 30 °C (e.g., Polymer2009, 50, 519). While phase separation occurs at 20 °C for the statistical copolymers, the influence of the monomeric sequential arrangement along the backbone was not addressed so far. Thus, we report on the thermosensitive properties of a diblock copolymer PDEAAM-b-PNIPAM and compare it to the homopolymers, mixtures thereof, and to the statistical copolymer of the same molecular weight. These polymers were prepared by controlled radical polymerization, namely Reversible Addition–Fragmentation Chain Transfer (RAFT). Their solution behavior was mainly studied by infrared spectroscopy (IR) of the amide I′ band and by turbidimetry. IR spectroscopy sees a decreasing hydration with heating even below the cloud point for all polymers. This results final...

Thermoresponsive cellulose-g–N,N′-diethyl acrylamide copolymers

Thermoresponsive cellulose-g–N,N′-diethyl acrylamide copolymers

Thermal analysis of polymer–water interactions and their relation to gas hydrate inhibition

AbstractGas hydrates formed in oil production pipelines are crystalline solids where hydrocarbon gas molecules such as methane, propane, and their mixtures are trapped in a cagelike structure by hydrogen‐bonded water molecules to form undesirable plugs. Methanol and glycol are currently used to prevent these plugs via thermodynamic inhibition. Small amounts of water‐soluble polymers may provide an alternate approach for preventing gas hydrates. In this study, we expand the fundamental understanding of water–polymer systems with differential scanning calorimetry. Nonfreezable bound water was used to quantify polymer–water interactions and relate them to the chemical structure for a series of polymers, including acrylamides, cyclic lactams, and n‐vinyl amides. For good interactions, the water structure needs to be stabilized through hydrophobic interactions. An increased hydrophobicity of the pendant group also appears to favor polymer performance as a gas hydrate inhibitor. Good inhibitors, such as poly(diethyl acrylamide) and poly(N‐vinyl caprolactam), also show higher heat capacities, which indicate higher hydrophobicity, than poor performers such as polyzwitterions, in which hydrophilicity dominated. The phase behavior and thermodynamic properties of dilute polymer solutions were also evaluated through measurements of the heat of demixing and lower critical solution temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2642–2653, 2007

Swelling and mechanical behavior of ionized poly(acrylamide-co-N,N’-diethylacrylamide) gels in water/acetone mixtures and in water at various temperatures

Ionized networks of random copolymers of acrylamide (AAm) and N,N’-diethylacrylamide (DEAAm) (mole ratios of xAAm/xDEAAm=1/0,0.75/0.25,0.5/0.5,0.30/70,0.15/0.85,0/1) with various amounts of ionic comonomer-sodium methacrylate (MNa) (mole ratios to all monomers xMNa=0.0,0.025,0.05) and crosslinker – N,N’-methylenbisacrylamide (MBAAm) were prepared at high dilution in water. Their swelling and mechanical behavior was investigated in water at various temperatures (from 10 to 90 °C) and in water/acetone (w/a) mixtures at room temperature. For some copolymers the transition region from expanded to collapsed state was observed at critical concentration of acetone, ac, in w/a mixtures or at critical temperature, Tc, in water. It was found that with increasing content of DEAAm component in copolymers the ac values increase; the similar increase was observed with increasing xMNa. Neat PDEAAm and copolymers with the highest DEAAm content exhibit temperature transition; both increasing amount of AAm and charges bound on the chains (xMNa) in copolymers shifts the Tc temperatures to higher values very efficiently (for more than 20 °C).

Phase transition in swollen gels: 7. Effect of charge concentration on the temperature collapse of poly( N, N-diethylacrylamide) networks in water

The swelling and mechanical behaviour of gels of the copolymer of diethylacrylamide (DEAAm) with a small quantity of sodium methacrylate (mole fraction x MNa = 0–0.067) swollen in water was investigated in the temperature range 1–80°C. For networks in the range x MNa > 0.0095 phase transition was observed; both the critical transition temperature T c,c and the extent of the collapse Δ c increase with increasing x MNa. The formation of associations in the collapsed state contributes to the overall extent of the transition; these structures give rise to stable turbid gels at elevated temperatures. Evidence for the formation of ‘associated’ structures is also supported by the observed independence of cloud temperature of the concentration of DEAAm, c, in the polymerization DEAAm-water mixture without the crosslinking agent in the range c = 0.5–80 vol%. While PDEAAm solutions are formed in the range c < 4.5–6 vol%, physical gels arise at higher concentrations.