N-dimethyl Acrylamide Research Articles

Synthesis and performance study of amphoteric polymer suspension stabilizer for cementing slurry at ultra-high temperature

As the number of ultra-deep wells increases, maintaining the suspension stability of cement slurry at ultra-high temperatures becomes increasingly challenging; the development of a suspension stabilizer suitable for ultra-high temperature environments is imperative. Therefore, this study synthesized a temperature-resistant polymer suspension stabilizer (LHAP) using 2-acrylamide-2-methylpropanesulfonic acid (AMPS), N, N-dimethyl acrylamide (DMAA), 4-acryloylmorpholine (ACMO), and quaternary ammonium cationic hydrophobic long-chain monomer hexadecyl dimethylallyl ammonium chloride (DMAAC-16) as raw materials. It was applied to maintain the suspension stability of cement slurry at ultra-high temperatures. The molecular structure and molecular weight of LHAP were characterized and tested using infrared spectroscopy, nuclear magnetic hydrogen spectroscopy, and Ubbelohde viscometer. The thermal stability and viscosity-temperature performance of LHAP were measured using thermogravimetric analysis and rheometer, respectively. Through the segmented density difference testing of cement stone columns, the suspension stability effect of LHAP on cement slurry under high temperature was evaluated. The suspension stabilization mechanism of LHAP was studied through fluorescence probe testing, variable temperature UV visible light testing, variable temperature particle size distribution testing, Zeta potential analysis, Environmental Scanning Electron Microscopy (ESEM) analysis, and scanning electron microscopy (SEM) analysis. The results indicated that the polymer suspension agent LHAP had excellent temperature resistance, and the molecules didn’t undergo significant thermal degradation below 302 ℃. At high temperatures of 220 ℃, LHAP could maintain the suspension stability of cement slurry, and the segmented density difference of cement columns was less than 0.01 g/cm3. Mechanism analysis revealed that in addition to enhancing temperature resistance by introducing sulfonic acid groups and rigid rings, LHAP also effectively maintains the stability of the slurry suspension at ultra-high temperatures by coordinating electrostatic interactions and molecular associations. LHAP can effectively solve the settlement instability problem of cement slurry under ultra-high temperature, which is beneficial for improving the safety and quality of cementing construction in ultra-deep wells.

PH-responsive biomass-based hydrogels for 5-fu delivery: Investigating the influential role of itaconic acid content on structural characteristic, swelling behavior, and drug loading capacity

The pH-responsive hydrogel was synthesized through an eco-friendly free radical polymerization process, utilizing ionic acid (IA), N, N-dimethyl acrylamide (DAAm), and double-bond modified vanillin (VMA). The P(DAAm-co-IA-co-VMA) hydrogel exhibited favorable compressive strength, swelling behavior, temperature sensitivity, pH sensitivity, salt solution sensitivity, and biocompatibility. Additionally, the study investigated the influence of varying IA monomer content on these properties. The evaluation of drug loading and release capabilities utilized 5-fluorouracil (5 Fu) as the model medicinal. The results showed that the P(DAAm-co-IA-co-VMA) hydrogel's cumulative release percentage was greater in the simulated intestinal fluid compared to the simulated gastric fluid, indicating its potential for oral drug delivery applications.

Preparation and performance evaluation of PDDSA-MS composite as high temperature and high salinity filtration additive

Drilling operations in deep and ultra-deep wells encounter challenges arising from high temperature and saltwater intrusion, leading to reduced drilling efficiency and deteriorated performance of water-based drilling fluids. In order to alleviate the problem of increased filtration of drilling fluid under harsh environment, the composite (PDDSA-MS) was prepared by free radical polymerization using N, N-dimethyl acrylamide (DMAA), Dimethyl diallyl ammonium chloride (DMDAAC), Sodium styrene sulfonate (SSS), 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and KH570 modified SiO2 as raw materials. This composite contained absorption groups, hydration groups, rigid groups and nanomaterials. Through rigorous performance evaluations, it was observed that the addition of 1 wt% composite to a fresh water drilling fluid, resulting in a remarkably low filtration of 8.8 mL after aging at 260 °C. Furthermore, when 3 wt% composite was added to the 15 wt% NaCl salt water drilling fluid, the filtration was 8 mL after aging at 220 °C. This was attributed to the particle size of the composite and its ability to maintain the dispersion stability of drilling fluid, decelerate bentonite agglomeration, and make the surface of the formed filter cake dense and smooth. These findings demonstrated the thermal stability exhibited by composite, offering an effective solution for drilling operations in deep and ultra-deep wells.

Research on graphene oxide modified polymer as multifunctional filtration reducer for oil-well cementing

Conventional filtration reducers have limited utility in cementing at deep oil and gas fields because of their poor temperature resistance and single function. As a novel multifunctional filtration reducer, graphene oxide-modified polymer GO-PADI was developed by radically copolymerizing 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N, N-dimethyl acrylamide (DMAM) and itaconic acid (IA) between graphene oxide sheets. The microstructure of GO-PADI was confirmed through the utilization of different methods such as fourier transform infrared spectroscopy (FT-IR). The performance evaluation results showed that GO-PADI had the high thermal stability, and could control filtration of cement slurry as conducted by the American Petroleum Institute (API) less than 50 mL, which is 17 % lower than that of the traditional filtration reducer PADI. GO-PADI could increase compressive strength of cement stone by 30.3 %, and decrease elastic modulus by 10.9 % in three-day curing period. GO-PADI has the multifunctional functions of reducing fluid loss, strengthening and toughening, and can effectively improve the engineering performances for high-temperature cement slurry.

Development of novel natural gas hydrate inhibitor and the synergistic inhibition mechanism with NaCl: Experiments and molecular dynamics simulation

Drilling fluid systems with exceptional performance serve as a foundation for commercial hydrate extraction. However, most hydrate reservoirs are located at relatively deep water depths and have shallow burial depths. As a result, there are high demands on the density of a hydrate drilling fluid system. Thus, the traditional hydrate drilling fluid system no longer meet the drilling needs in deep water shallow hydrate reservoirs. In this paper, a copolymer SYZ-2 was synthesized based on N-Vinyl-ε-caprolactam and N, N-dimethyl acrylamide. The effects of SYZ-2 and its NaCl system on methane hydrate were first tested by a constant rate cooling method, and the inhibition mechanisms of the system on hydrate nucleation and formation were investigated by molecular simulations. Meanwhile, the formulation and properties of a low-density hydrate drilling fluid system (1.06 g/cm3) based on SYZ-2 were also described in detail. The experimental results show that the hydrate formation temperature with the influence of SYZ-2 decreases from 10.6 °C to 2.7 °C, which can even be significantly reduced to −3.1 °C in the presence of 7 % NaCl. The molecular dynamic simulation results show that SYZ-2 inhibits the nucleation of hydrates by decreasing the solubility of methane molecules, primarily by promoting the agglomeration of methane molecules. Additionally, SYZ-2 can also adsorb to the surface of hydrates and prevent the hydrate cage structure from capturing methane molecules. In contrast, NaCl inhibits hydrates formation by restricting the movement of water molecules. These results provide valuable insights into a better understanding of the gas hydrate inhibition mechanisms, the rational development of high-performance hydrate inhibitors for drilling fluids, as well as the construction of drilling fluid systems.

Microscopic molecular and experimental insights into multi-stage inhibition mechanisms of alkylated hydrate inhibitor

A deep understanding of the mechanism of hydrate inhibitors on hydrate formation is crucial for the development of efficient natural gas hydrate inhibitors. However, the current understanding of the inhibitory mechanism of hydrate inhibitors in the nucleation and formation processes is still very limited, which greatly hinders the development of new types of hydrate inhibitors. In this study, the solution polymerization method was employed to prepare poly (N-vinyl pyrrolidone-co-N,N-dimethyl acrylamide), as a new kinetic hydrate inhibitor. The inhibition properties were investigated by the constant cooling test and the step cooling test. Meanwhile, the multi-stage inhibition mechanisms of alkylated hydrate inhibitor were also revealed based on molecular simulations. The results of experiments and molecular simulations illustrate that the mechanism of the inhibitors varies at different stages. The inhibitors retard hydrate formation by reducing the solubility of methane molecules in water during the nucleation phase. However, during the formation phase, the hydrate inhibition is achieved by adsorption. In particular, the absorption of poly (vinyl pyrrolidone) on the surface of hydrate can be effectively improved by alkylation, and the interaction energy of poly (N-vinyl pyrrolidone-co-N,N-dimethyl acrylamide) with the hydrate nucleus was increased by 3.22 times compared to poly (vinyl pyrrolidone). It resulted in an increase in subcooling of 8.2 °C. Also, the effective induction time of poly (N-vinyl pyrrolidone-co-N,N-dimethyl acrylamide) at 8 °C was extended to 987 min. A molecular model for evaluating the interaction of inhibitors with hydrates is also successfully developed, which corresponds well to the experimental results. These results contribute to a better understanding of hydrate formation in drilling fluids and implications for developing new materials for high-performance hydrate drilling fluids.

Polyethylene/poly (N, N-dimethyl acrylamide) hybrid hydrogel membrane for total heat exchanger

For the total heat exchange membrane, there is a compromise effect between the moisture permeability and the gas barrier. To overcome this challenge, a new type of total heat exchange membrane was proposed involving a porous polyethylene (PE) membrane and a hydrophilic poly (N, N-dimethyl acrylamide) (PDMAA) hydrogel. A dense PE/PDMAA composite membrane was fabricated via an in situ photoinitiated free-radical polymerization and cross-linking reaction through a pre-permeation of N, N-dimethyl acrylamide (DMAA) monomers in the porous structure of the PE membrane. In this study, we systematically investigated the effect of varying amounts of PDMAA filler on membrane morphology, hydrophilicity, stability, mechanical properties, water vapor transmission rate, gas barrier property, and total heat exchange efficiency. These results demonstrate that a tight, stable PE/PDMAA hybrid membrane with an interlocked structure has been created. Water vapor diffusion channels and an efficient carbon dioxide (CO2) barrier were successfully constructed through the introduction of a cross-linked PDMAA hydrogel. Improvements in water vapor transmission rate and reduction in CO2 transmission rate were achieved simultaneously with increasing PDMAA filling amount. Excellent mechanical properties and hybrid stability were also observed for the composite membrane obtained. This work provides a novel total heat exchange membrane with convenient production process, low cost and high durability characteristics.

Integration of high strength, resilience and stretchability into the nanocomposite hydrogel sensor for a wide working range detection and underwater sensing

Hydrogel sensors have drawn tremendous attention due to the combination of stretchability, biocompatibility, and convenient production. The integration of high mechanical strength, stretchability and a wide working range towards various application environment is still a great challenge. Herein, both the tough and highly stretchable hydrogel sensor was developed and showed large working range and good sensing capability towards various deformation and underwater motions. The hydrogel was constructed by the polymerization of acrylic acid, acrylamide and N, N-dimethyl acrylamide, and crosslinked by the zirconium hydroxide. The obtained hydrogel exhibits high mechanical strength (∼1.5 MPa), strain (∼1400%) with good toughness (∼12 MJ/m−3), recovery properties and high elasticity (G’∼23 KPa) which was beneficial for the stable sensing performance. It also showed high sensitivity in a wide working range (0–1300%), and exhibited stretching-dependent resistance signal monitoring capability on large, small, cyclic deformations, and various human motions (wrist, finger bending and swallowing). Moreover, it can detect various motions underwater, even monitor the pulse beating for healthcare in the liquid environment. This hydrogel with these comprehensive mechanical and sensing performances has great potential in the fields of artificial intelligence and electric skins, and further applied in the aquatic environment.

A zwitterionic copolymer as fluid loss reducer for water-based drilling fluids in high temperature and high salinity conditions

With the exploration and development of deep and ultra-deep oil/gas resources, higher challenges have been placed on the performance of water-based drilling fluids (WBDFs). Integrating synergistic characteristics such as excellent high temperature- and salt-resistance, rheology, and fluid loss control capabilities is still a massive challenge for water-based drilling fluid loss reducers. Herein, an innovative temperature- and salt-resistant zwitterionic copolymer filtration reducer was synthesized using N, N-dimethyl acrylamide, 1-(2-carboxyethyl)-3-vinyl imidazolium chloride, sulfobetaine vinyl imidazole through free radical copolymerization. Due to the excellent rigid cationic imidazole ring and salt-resistant hydration groups in the copolymer, the copolymer can be efficiently adsorbed on the surface of bentonite particles through strong electrostatic force and hydrogen bonds, thus maintaining the excellent hydration and dispersibility of bentonite particles. Even after aging at high temperatures (up to 200 °C) and high salinity (saturated salt) conditions, the DCS-based drilling fluids still exhibit excellent rheological and filtration properties (FLAPI < 10 mL), showing the potential for application in deep and ultra-deep drilling operations.

Anionic Copolymers with Different Charge Densities for Regulating the Properties of Cement Pastes.

Self-compacting concrete (SCC) is an extremely flowable concrete, which increases the probability of segregation and bleeding. Viscosity-modifying admixtures (VMAs) have been developed to improve the stability of SCC. Synthetic polymer VMAs have excellent water solubility and stability, and can be easily chemically prepared and modified. In this work, a series of copolymers based on anionic 2-acrylamido-2-methyl-propanesulfonic acid (AMPS) and nonionic N, N-dimethyl acrylamide (DMAA), with similar molecular weights but different charge densities, were prepared. The effect of the charge density of the anionic polymers on the fluidity, rheological property, and adsorption behavior of the cement pastes was investigated. The action mechanism of the polymers was discussed. The results indicate that the charge density of anionic polymer VMAs is of great significance for the development of cost-effective SCCs with good rheological properties.

Swelling studies on poly(n, n-dimethyl acrylamide-co-acrylic acid) hydrogels

Hydrogel copolymers based on N, N-dimethyl acrylamide (DMA) and acrylic acid (АAc) were synthesized with different molar composition ratios ([DMA-AAc] = 30÷70, 50÷50 and 70÷30) using ammonium peroxydisulfate as a free radical initiation system and in the presence of various amounts of N, N’-methylene bis (acrylamide) as a crosslinker agent (0.05, 0.1 and 0.3 mol. %) and water as reactant medium. The swelling technique characterized the obtained copolymer by different amounts to added of the crosslinking agent. While a large amount of crosslinking agent in the poly (DMA-co-AAc) hydrogels was reduced the swelling degree in the water medium, a smaller amount in the gel indicated the tendency of the gel to burst. Absorption studies were made using on different concentrations of copper sulphate (CuSO4). Poly (DMA-co-AAc) hydrogels absorption capacity is competitive when there is more N, N-dimethyl acrylamide content in copolymer than others. The swelling ratios of low concentration of Cu (II) ion are higher than those of higher concentration of Cu (II) ion. Hydrogel gave the highest swelling ratio for the solution containing the lowest Cu (II) ion concentration than for the solution containing the highest Cu (II) ion.

Acrylate based post-acting polymers as novel viscosity modifying admixtures for concrete

In this work, post-acting polymers were utilized as novel viscosity modifying admixtures (VMAs) for the first time. A series of the random terpolymers containing anionic acrylic acid (AA), nonionic hydroxypropyl acrylate (HPA) and N, N-dimethyl acrylamide (DMAA) was synthesized. By changing the concentration of initiator, the copolymers with different acrylate segment (HPA) contents and similar molecular weights were obtained. The adsorption, fluidity, bleeding and rheological properties of the cement paste containing different copolymers have been discussed. The effects of the acrylate segments of the copolymers on the properties of cement paste were studied. The results show that the post-acting polymers are hydrolyzed and adsorb on the cement particle surface gradually, meanwhile decrease the bleeding and stabilize the cement paste slowly. The viscosity modifying effects of the post-acting polymers on cement enhance gradually and maintain for a long time.

Characterization and swelling properties of copolymer Poly(N, N-dimethyl acrylamide -co-acrylic acid) and homopolymer Poly (acrylic acid)

This paper investigates the swelling properties of homopolymer and copolymer hydrogels. Copolymeric hydrogels based on N, N-dimethyl acrylamide and acrylic acid (poly(DMA-co-AAc) as well as homopolymer hydrogels based on acrylic acid (polyAAc) were synthesized by radical technique in aqueous solutions using ammonium persulfate as an initiator and N, N-methylene-bis-acrylamide as a crosslinking agent. The properties of hydrogels examined including scanning electron microscopy (SEM) and FT-IR. The results indicate that the poly(DMA-co-AAc) copolymer has a high swelling ability in an aqueous solution. The swelling of hydrogels were achieved a maximum degree and diameter of 270 and 63mm in water, respectively. The swelling behavior of these hydrogels was investigated to determine function of the effect of pH and polymeric compositions.

Precise Tuning of Polymeric Fiber Dimensions to Enhance the Mechanical Properties of Alginate Hydrogel Matrices.

Hydrogels based on biopolymers, such as alginate, are commonly used as scaffolds in tissue engineering applications as they mimic the features of the native extracellular matrix (ECM). However, in their native state, they suffer from drawbacks including poor mechanical performance and a lack of biological functionalities. Herein, we have exploited a crystallization-driven self-assembly (CDSA) methodology to prepare well-defined one-dimensional micellar structures with controlled lengths to act as a mimic of fibrillar collagen in native ECM and improve the mechanical strength of alginate-based hydrogels. Poly(ε-caprolactone)-b-poly(methyl methacrylate)-b-poly(N, N-dimethyl acrylamide) triblock copolymers were self-assembled into 1D cylindrical micelles with precise lengths using CDSA epitaxial growth and subsequently combined with calcium alginate hydrogel networks to obtain nanocomposites. Rheological characterization determined that the inclusion of the cylindrical structures within the hydrogel network increased the strength of the hydrogel under shear. Furthermore, the strain at flow point of the alginate-based hydrogel was found to increase with nanoparticle content, reaching an improvement of 37% when loaded with 500 nm cylindrical micelles. Overall, this study has demonstrated that one-dimensional cylindrical nanoparticles with controlled lengths formed through CDSA are promising fibrillar collagen mimics to build ECM scaffold models, allowing exploration of the relationship between collagen fiber size and matrix mechanical properties.

Phosphate enhanced self-healing property of phenylborate-based hydrogel at neutral environment

Self-healing hydrogels based on phenylboronate ester bonds are of huge interest in polymer science. However, most of these hydrogels only heal themselves at pH above their pKa (mostly > 8.0), which reduces their potential application in physiologic environments. Here, we showed that a small amount of phosphate produced stable hydrogels, able to support their self-healing at neutral pH. The hydrogel was formed by poly (3-acryloxymethylphenylboronic acid-co-N, N-dimethyl acrylamide) and poly (D-gluconamidoethyl methacrylate-co-N, N-dimethyl acrylamide) in phosphate buffer. Self-healing was observed at pH = 7.0. Intermolecular interactions between phenylboronic acid and phosphate were suggested by rheology, DSC determination and QTAIM calculations. The study represents a new mechanism to promote phenylboronate-based hydrogel formation and self-healing at neutral environment and, more importantly, provides considerable insight into their application in physiologic conditions including sensors and tissue engineering.

A Superstrong and Reversible Ionic Crystal-Based Adhesive Inspired by Ice Adhesion.

In this study, we developed a superstrong and reversible adhesive, which can possess a high bonding strength in the "adhesive" state and detach with the application of heating. An ionic crystal (IC) gel, in which an IC was immobilized within a soft-polymer matrix, were synthesized via in situ photo-crosslinking of a precursor solution composed of N, N-dimethyl acrylamide (DMAA) and a melted IC. The obtained IC gel is homogenous and transparent at melt point. When cooled to the phase transition temperature of the IC, the gel turns into the adhesive with the adhesion strength of 5.82 MPa (on glasses), due to the excellent wetting of melted gel and a thin layer of crystalline IC with high cohesive strength formed on the substrates. The synergistic effects between IC, polymer networks and substrates were investigated by solid state 1 H NMR and molecular dynamics simulation. Such an adhesive layer is reversable and can be detached by heating and subsequent re-adhesion via cooling. This study proposed the new design of removable adhesives, which can be used in dynamic and complex environments.

Effects of the charge density of anionic copolymers on the properties of fresh cement pastes

In this work, the effects of the charge density of the anionic copolymers on the properties of fresh cement pastes were fully discussed. A series of random copolymers based on anionic acrylic acid (AA) and nonionic N, N-dimethyl acrylamide (DMAA) were prepared by free radical solution polymerization. By varying the initiator concentration, the obtained polymers have different charge densities but similar molecular weights. The adsorption, fluidity, bleeding and rheology of the cement pastes mixed with different polymers were tested, respectively. The results indicate that the anionic and nonionic monomer of the polymers effect on the properties of fresh cement paste cooperatively, and the polymer with medium charge density can effect on the cement paste strongest. Our study is quite beneficial to understand the structure–property relationships and action mechanism of anionic polymers in cement pastes.

Organosilicate polymer as high temperature Resistent inhibitor for water-based drilling fluids

In this study, the inhibition property of an organosilicate polymer was investigated as an inhibitor for water-based drilling fluids. A novel polymer was prepared using 2-acrylamido-2-methylpropane sulphonic acid (AMPS), N, N-dimethyl acrylamide (DMAA), maleic anhydride (MA), and γ-methacryloxypropyl trimethoxy silane (MEMO) as the polymerisation monomers, named as ADMM. Also, the inhibition performance was evaluated by an immersion test, a linear swelling test, and a shale cuttings recovery test. Compared with that of the other inhibitors, the addition of ADMM can effectively inhibit the swelling of mud balls, resulting in the lowest swelling height of the drilling fluid. ADMM was characterised using a thermogravimetric analysis, a Fourier transform infrared spectrometer, a nuclear magnetic resonance instrument, a laser particle size distribution instrument, and a zeta potentiometric analyser. The results showed that the decomposition temperature of ADMM was 330 °C. The shale cuttings recovery of the 1.0% ADMM solution at 150 °C was 76.32%. The dynamic shear rise rate was as low as 160%. Furthermore, ADMM was adsorbed on the clay surface at many points to form a “protective film” of the polymer, thus inhibiting the hydration of the clay.

Synthesis and working mechanism of fluid loss additive by freeze-drying method

ABSTRACT A liquid fluid loss additive was synthesized by 2-acrylamide-2-methyl propane sulfonic acid (AMPS), N, N-dimethyl acrylamide (DMAM), maleic anhydride (MA), and allyl alcohol polyoxyethylene ether (APEG), which named ADMA (AMPS/DMAM/MA/APEG). The liquid ADMA was freeze-dried and grinded to a white powdery polymer (FDADMA). The FDADMA had less fluid loss volume and superior rheological properties both in fresh water and sea water, while ADMA merely exhibited good filtrate loss control and rheology in fresh water. Besides, the surface morphology of FDADMA was dendritic in sea water after freeze drying, while the ADMA was severely aggregated in sea water.

In vivo photothermal inhibition of methicillin-resistant Staphylococcus aureus infection by in situ templated formulation of pathogen-targeting phototheranostics.

Bacterial infection has caused a serious threat to human public health. Methicillin-resistant Staphylococcus aureus (MRSA) is a representative drug-resistant bacterium, which is difficult to eradicate completely, resulting in high infection probability with severe mortality. Herein, pathogen-targeting phototheranostic nanoparticles, Van-OA@PPy, are developed for efficient elimination of MRSA infection. Van-OA@PPy nanoparticles are fabricated from the in situ templated formation of polypyrrole (PPy) in the presence of ferric ions (Fe3+) and a polymer template, hydrophilic poly(2-hydroxyethyl methacrylate-co-N,N-dimethyl acrylamide), P(HEMA-co-DMA). PPy nanoparticles are further coated with vancomycin conjugated oleic acid (Van-OA) to afford the resultant pathogen-targeting Van-OA@PPy. A high photothermal conversion efficiency of ∼49.4% is achieved. MRSA can be efficiently killed due to sufficient nanoparticle adhesion and fusion with MRSA, followed by photothermal therapy upon irradiation with an 808 nm laser. Remarkable membrane damage of MRSA is observed, which contributes greatly to the inhibition of MRSA infection. Furthermore, the nanoparticles have high stability and good biocompatibility without causing any detectable side effects. On the other hand, residual Fe3+ and PPy moieties in Van-OA@PPy endow the nanoparticles with magnetic resonance (MR) imaging and photoacoustic (PA) imaging potency, respectively. The current strategy has the potential to inspire further advances in precise diagnosis and efficient elimination of MRSA infection in biomedicine.