Acrylamide-acrylic Acid Research Articles

Efficient encapsulation of water soluble inorganic and organic actives in melamine formaldehyde based microcapsules for control release into an aqueous environment

Melamine formaldehyde (MF) is a versatile and widely used chemical cross-linking agent in microcapsule shells for the encapsulation of oil phases in an aqueous continuum. However, it has not been possible to form MF microcapsules with water soluble actives, to achieve sustained/no release in aqueous environment. Herein, 5 types of MF based microcapsules were designed and synthesised with 4 polymers, including neutral and polar poly(acrylamide-acrylic acid), anionically charged biocompatible shellac and ion exchange resin polystyrene sulfonate as well as a superhydrophobic polymer precursor octadecyltrichlorosilane, via an in situ polymerisation method. Potassium chloride and allura red (dye, Mw = 496.42 g·mol−1) were used as models of inorganic and organic water soluble actives with low molar mass, respectively, to study their size distributions, encapsulation efficiencies, payloads, morphologies and release rates in aqueous environment. The release rates ranged from complete release within 15 min to no release up to 1 month in aqueous environment.

Surface modification of multiwalled carbon nanotubes via surface RAFT copolymerization method and capecitabine-loaded anticancer hydrogel for controlled drug delivery in stomach

ABSTRACT In our work, reversible addition-fragmentation chain transfer (RAFT)/carbon nanotube (CNT)/acrylic acid (AA)/acrylamide (AAm) nanocomposite was synthesized by living radical polymerization. The structure and surface morphology of the synthesized RAFT-CNT-Hydrogel nanocomposites were analyzed by FTIR, 1HNMR, SEM, TEM, XRD, and TGA/DTG techniques. The results indicated that PAA/AAm chains grafted with CNT by RAFT polymerization. RAFT-CNT-Hydrogel nanocomposites for drug release investigated in different buffers resulted in a strong pH-sensitive behavior. In total, the obtained hydrogel drug-delivery systems are presented a proper effect versus stomach cancer in vitro and in vivo, and it can be used as candidates for controlled release of anticancer drugs in stomach with exalted remedial agents.

Preparation of Fe3O4@SiO2@ P(AANa-co-AM) Composites and Their Adsorption for Pb(II).

A series of magnetic composites of sodium polyacrylate and polyacrylamide copolymer [Fe3O4@SiO2@P(AANa-co-AM)] were prepared. The investigation showed that the adsorption efficiency of Pb(II) was the best when the acrylamide/acrylic acid (AM/AA) mass ratio of composites was 5:5. Therefore, the composite of this ratio was selected as the adsorbent to systematically adsorb Pb(II) in aqueous solution. Static adsorption of Pb(II) to the magnetic composites in aqueous solutions was investigated by varying the solution pH and the concentration of Pb(II). The adsorption kinetics and isotherms model of Pb(II) on the Fe3O4@SiO2@P(AANa-co-AM) composites followed a pseudo-second-order model and the Langmuir isotherm model, respectively. When the temperatures were 298.15, 308.15, and 318.15 K, the maximum adsorption capacities of Fe3O4@SiO2@P(AANa-co-AM) composites were 237.53, 248.14, and 255.10 mg/g, respectively. The thermodynamic study of adsorption showed that the adsorption of Pb(II) on Fe3O4@SiO2@P(AANa-co-AM) composites was a spontaneous endothermic process. The X-ray photoelectron spectroscopy (XPS) analysis showed that the adsorption of Pb(II) was due to the chelation between −COO– and Pb(II). After four adsorption–desorption cycles, the adsorbent can still maintain a high adsorption capacity.

An improved metal cation capture on polymer with graphene oxide synthesized by gamma radiation

The enhancement of polymer capacity is extremely important for removal of metal ions from their solutions. Herein, we have used graphene oxide nano-sheets with polymer to enhance the polymer capacity towards Sr2+ and Co2+ ions. Therefore, poly(acrylamide-acrylic acid)- graphene oxide, p(AM-AA)GO, nanocomposite was prepared with template polymerization technique using gamma radiation as an initiator at radiation dose 40 kGy. The cross-linked p(AM-AA) with/without graphene oxide was emphasized using different analytical techniques such as SEM, FTIR, XRD and TGA. The obtained p(AM-AA)GO nanocomposite and pure polymer were tested for removal of Sr2+ and Co2+ ions from aqueous solution. The results showed that the presence of GO with p(AM-AA) enhanced the adsorption amount from 210 mg/g to 296 mg/g for Co2+ ions while enhanced from 192 mg/g to 260 mg/g for Sr2+ ions. The nature of adsorption was studied using theoretical models such as kinetics and isotherms models. The theoretical models displayed that the adsorption of Sr+2 and Co2+ ions was obeyed to Langmuir isotherm, pseudo second order kinetic. In addition, the thermodynamic estimations was revealed that the adsorption process is irreversible, spontaneous nature and slightly improved with temperature rising.

State of ions and water molecules in the water salt solutions of polyacrylamide and co-polymer of “acrylamide–acrylic acid Na/k salt”

Geometrical and electronic parameters of the microstates of the molecular models of polyacrylamide and co-polymers of acrylamide-acrylic acid in aqueous solutions of sodium and potassium chlorides were computed by the non-empirical SCF MO LCAO method with the use of the basis MINI Huzinaga. The models contained four monomeric units of the polymer, including two metal carboxylate groups, 80 water molecules and two pairs of ions Na+ and Cl– or K+ and Cl–. It follows from the calculation results that there is a principal difference in the hydration of Na+ and K+: the Na+‧‧‧О2– bond is shorter than the sum of the radii of the interacting ions, while the k+‧‧‧O2– bond is equal or longer. This indicates that in the first case, the bonds are partially covalent, while in the second one they are pure electrostatic. All elements of the molecular models in the both cases are combined by the intermolecular bonds forming a spatial net. The polymer molecules have a flexible chain with oxygen containing functional groups that are built into the structure of the salt solutions without distorting it. We assume that this is the main reason for the good solubility of the studied polymers in the aqueous salt solutions.

Effect of salt and temperature on molecular aggregation behavior of acrylamide polymer

AbstractThree kinds of acrylamide copolymers were synthesized in this paper, acrylamide (AM) homopolymer, acrylamide/acrylic acid (AA) copolymer and acrylamide/2-acrylamide-2-methylpropanesulfonic acid (AMPS) copolymer by free radical polymerization. The aggregation behaviours of these polymers in salts water solution were studied. The molecular chains of homopolymer were stretched in salt water solutions, since it did not undergo hydrolysis and there were no charges in the backbone and side chains. Therefore, the conformation of homopolymer was hard to be attacked by salt ions. However, the copolymers synthesized from these monomers had large number of anionic groups. These anions were easily attracted by cations from salt solutions forming ionic bonds, which led to changes in molecular conformation. The viscosity of copolymer decreased since the molecular chains were crimped. The viscosity of copolymer decreased distinctly according to the temperature of different salt solutions, as temperature had great impact on the viscosity of copolymer. The interaction mechanism of polymers exhibited great difference in salts solutions, comparing to temperature. High temperature reduced the entanglement between molecular chains, whereas salt ions neutralized the negative charges on the molecular chains causing curling of molecular chains.

Potentiality of uranium extraction from acidic leach liquor by polyacrylamide-acrylic acid titanium silicate composite adsorbent

ABSTRACTUranium has an important role in nuclear reactors and nuclear power supply. In this study, the recovery of uranium from sulphate leach liquor was investigated using synthesised poly (acrylamide-acrylic acid)-titanium silicate (P-(AM-AA)-TS) composite as an adsorbent. The polymer composite was prepared by gamma radiation polymerisation of acrylic acid (AA monomer), polyacrylamide (PAM, template), bisacrylamide (BAA, crosslinker) and titanium silicate as an adsorbent for uranium recovery. The (P-(AM-AA)-TS) was studied for recovery of uranium from sulphate leach liquor. Different reaction parameters affecting the uranium sorption were investigated, namely pH, contact time, temperature, uranium concentration and a dose of the adsorbent to sulphate leach liquor. Adsorption per cent of uranium reached 98.6% from leach liquor of pH 2.5; initial uranium concentration is 700 mg/L at room temperature using 0.1 g P-(AM-AA)-TS adsorbent for 120 min. The theoretical studies showed that the batch isotherm fits with the Langmuir model. The adsorption capacity of the adsorbent reached 64.1 mg/g based on the Langmuir model.

Evaluation of hydroxyapatite/poly(acrylamide-acrylic acid) for sorptive removal of strontium ions from aqueous solution.

A composite polymer, hydroxyapatite/poly(acrylamide-acrylic acid), was synthesized by gamma-induced polymerization. The factors affecting the sorption process were evaluated. The removal increased with time and achieved equilibrium after 1 h for all initial concentration ranges (10-50 mg/L). The highest removal of Sr(II) was achieved using 50 mg/L at pH 6. The sorption process was found to follow a pseudo-first-order mechanism. The equilibrium data are best described by the Langmuir model, with a monolayer capacity of 53.59 mg/g. The values of thermodynamic parameters indicate that the sorption process is endothermic (ΔH > 0), increases randomness (ΔS > 0) and is spontaneous (ΔG < 0). The results imply that the composite could be used as a promising low-cost material for the removal of radionuclides from radioactive waste.

Metallohydrogel with Tunable Fluorescence, High Stretchability, Shape-Memory, and Self-Healing Properties.

Aiming at the problem that the reported smart optical metallohydrogels were limited with poor mechanical properties, we reported here a novel smart optical metallohydrogel (Al-hydrogel) with excellent elongation, shape-memory ability, self-healing property, and controllable fluorescence intensity. The Al-hydrogel was obtained by the HHPMA-Al3+ and carboxylate-Al3+ coordination after one-pot micellar copolymerization of acrylic acid (AAc), acrylamide (AAm), and hydrophobic arylhydrazone-based ligand (HHPMA). This hydrogel was able to extend up to 5000% of its original length without fracture. Its emission intensity was tunable by OH-/H+ or Zn2+/AAc and increased by 500% with 0.1 M OH- or Zn2+. Its tunable fluorescence enabled us to repeatedly pattern it. A reversible system consisting of Fe3+/H+, was implemented to control the shape of the Al-hydrogel, endowing the Al-hydrogel with shape-memory ability. This highly stretchable and multifunctional Al-hydrogel has potential applications in information transmission, wearable devices, and flexible sensors.

Radiochemical separation of reactor produced Sc-47 from natural calcium target using Poly(acrylamide-acrylic acid)/multi-walled carbon nanotubes composite

Poly (acrylamide-acrylic Acid)/multi-walled carbon nanotubes composite [P(AAm-AA)/MWCNTs] was prepared by gamma radiation to initiate the copolymerization of AAm and AA onto MWCNTs surface. The structural characteristics were confirmed by FT-IR, SEM, XRD, TGA and DTA. The particle size distribution was determined by dynamic light scattering (DLS). [P(AAm-AA)/MWCNTs] was used to study the adsorption efficiency of 47Sc from natural calcium by batch technique at different concentrations of HCl and/or HNO3 acid solutions. No-carrier-added 47Sc (III) was separated from 47Ca(II) on [P(AAm-AA)/MWCNTs] column matrix. The elution efficiency of about 80 ± 1.5% was attained for 47Sc(III) using 1M HNO3. Three quality control tests, radionuclidic, radiochemical and chemical purities were investigated to emphasis that 47Sc secure for use in nuclear medicine.

Stomach-Specific Drug Delivery of Clarithromycin Using a Semi Interpenetrating Polymeric Network Hydrogel Made of Montmorillonite and Chitosan: Synthesis, Characterization and In Vitro Drug Release Study.

Purpose: In this study, we aimed to prepare an extended drug delivery formulation of clarithromycin (CAM) based on a semi-interpenetrating polymer network (semi-IPN) hydrogel. Methods: Synthesis of semi-IPN hydrogel nanocomposite made of chitosan (CS), acrylic acid (AA), acrylamide (AAm), polyvinylpyrrolidone (PVP), and montmorillonite (MMT) was performed by free radical graft copolymerization method. Swelling kinetic studies were done in acidic buffer solutions of hydrochloric acid (pH = 1.2), acetate (pH = 4), and also distilled water. Also, the effects of MMT on the swelling kinetic, thermal stability, and mechanical strength of the hydrogels were evaluated. Moreover, in vitro release behavior of CAM and its release kinetics from hydrogels were studied in a hydrochloric acid buffer solution. Results: Fourier transform infrared spectroscopy (FTIR) results revealed that synthesis of semi- IPN superabsorbent nanocomposite and CAM incorporation into hydrogel was performed, successfully. Introducing MMT into hydrogel network not only improved its thermal stability but also increased mechanical strength of the final hydrogel product. Also, in comparison with neat hydrogel (1270 g/g), hydrogel nanocomposite containing 13 wt% MMT exhibited greater equilibrium swelling capacity (1568 g/g) with lower swelling rate. In vitro drug release experiments showed that CS-g-poly(AA-co-AAm)/PVP/MMT/CAM formulation possesses a sustained release character over extended period of time compared with CS-g-poly(AA-co- AAm)/PVP/CAM formulation. Conclusion: In the presence of MMT, the effective life time of drug is prolonged, demonstrating a sustained release property. The reason is that interlinked porous channels within superabsorbent nanocomposite network hinder penetration of aqueous solutions into hydrogel and subsequently cause a slower drug release.

Solar thermal energy storage based on sodium acetate trihydrate phase change hydrogels with excellent light-to-thermal conversion performance

Phase change materials (PCMs) play significant roles in solar thermal energy storage. In this work, a novel PCM, light-to-thermal conversion phase change hydrogel (LTPCH) consisting of NaAc·3H2O, acrylamide-acrylic acid sodium co-polymer and CuS was prepared using a melt impregnation process. The morphologies, thermal physical properties, light-to-thermal conversion performance and cycling lifetimes of prepared LTPCHs were investigated. A fluid leakage test showed that LTPCH containing 87 wt% NaAc·3H2O can keep a solid-gel structure without liquid leakage in the phase change process. Scanning electron microscope micrographs confirmed that LTPCH was structured by near-spherical particles which were mainly composed of NaAc·3H2O confined in the three-dimensional polymer networks. Differential scanning calorimeter tests revealed that the melting temperature of LTPCH was 57.1 °C, close to that of NaAc·3H2O, and its latent heat was as high as 202.4 J/g. The light-to-thermal conversion experiments indicated that CuS was an effective photon capturer and it can provide LTPCH with an excellent light-to-thermal conversion efficiency of 87.1%. After 300 melting/freezing cycles, LTPCHs maintained good thermal physical properties and high light-to-thermal conversion efficiency, and therefore showed great potential for use in solar thermal energy storage.

Tuning Cobalt and Nitrogen Co-Doped Carbon to Maximize Catalytic Sites on a Superabsorbent Resin for Efficient Oxygen Reduction.

The electrocatalytic performance and cost of oxygen reduction reaction (ORR) catalysts are crucial to many renewable energy conversion and storage systems/devices. Recently, transition-metal/nitrogen-doping carbon catalysts (M-N-C) have attracted tremendous attention due to their low cost and excellent catalytic activities; however, they are restricted in large-scale commercial applications by complex preparation processing. Here, a facile strategy to prepare Co-N-C catalysts has been developed. A kind of superabsorbent resin normally found in diapers, poly(acrylic acid-acrylamide), is used to adsorb a transition-metal cobalt salt and a pyrolysis strategy at 800 °C under an argon atmosphere is followed. The resin simultaneously plays a multiple role, which includes structural support, dispersing cobalt ions by coordinate bonds, and providing a carbon and nitrogen source. Attributed to the conductive carbon frameworks and abundant catalytic sites, the Co-N-C catalyst exhibits an excellent electrocatalytic performance. High onset potential (0.96 V vs. reversible hydrogen electrode, RHE), half-wave potential (0.80 V vs. RHE), and a large diffusion-limited current density (4.65 mA cm-2 ) are achieved for the ORR, which are comparable or superior to the commercial 20 % Pt/C and reported M-N-C ORR electrocatalysts. This work provides a universal dispersion technology for Co-N-C catalyst, which makes it a very promising candidate toward the ORR.

Joint double-network hydrogels with excellent mechanical performance

Based on the tough double-network hydrogel, a further crosslinked DN network hydrogel was developed and named joint double network (JDN) hydrogel. The JDN hydrogel consisting of ionically cross-linked sodium alginate (SA) as the first network, the chemically cross-linked poly (acrylamide-acrylic acid) (PAMAAc) as the second network and both of them combined together by ferric ions. As a result, SA/PAMAAc-Fe3+ hydrogels exhibited high mechanical strength with tensile stress of 1.26 MPa and tensile strain of 653%. Ultraviolet–visible spectroscopy, rheological and swelling tests also illustrated that the JDN structure greatly improved the mechanical properties of hydrogels because of close integration of internal networks. Moreover, the SA/PAMAAc-Fe3+ JDN hydrogel also owned high water content of 85%, free-plasticity, and excellent electrical property, which allowed it to be easily molded various shapes for tough electronic devices, flexible electrodes, and wearable equipment.

Polyacrylamide copolymer/aminated carbon nanotube‐based aqueous nanofluids for application in high temperature and salinity

ABSTRACTPolymer aqueous nanofluids have numerous industrial applications due to their synergic properties as a polymer and nanoparticle in the same fluid. The main goal of this work was to prepare stable aqueous nanofluids with improved viscosity in high temperature and salinity conditions. Aminated carbon nanotube (OCNT‐TEPA) presented a CN photoemission peak at 285.5 eV in X‐ray photoelectron spectroscopy spectra, which is evidence of a grafting reaction. Fourier transform infrared spectra presented absorption bands attributed to amide and amine bonds. Elemental analyses showed 1.9 and 3.2 mass % N content increases for OCNT‐TEPA and OCNT‐TEPA‐AM, respectively. Samples aged at 70 °C in brine confirmed that the addition of OCNT‐TEPA increased the viscosity of nanofluids to 30% at day 90 compared to acrylamide–acrylic acid copolymer fluids. Nanotubes presented only 35% of the aminated functions compared to carbon black (Lima et al., Carbon 2016, 109, 209) , and their effects in the enhancement of viscosity and thermal and colloidal stability were 2× greater. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46382.

Impact Assessment of Cetyltrimethylammonium Bromide Treated Organically Modified Nanoclay-Polymer Composite on Soil Enzyme Activity and Root Volume

The effect of organically modified nanoclay-polymer composite was evaluated on soil enzyme activity and root volume at different growth stages viz. crown root initiation, tillering and panicle initiation of wheat (variety: HD 3059). Nanoclay-polymer composite was synthesized by in -situ polymerization of acrylic acid-acrylamide in presence of cetyltrimethylammonium bromide @ 60% neutralization degree and 0.5% cross-linker level and subsequently loaded with di-ammonium phosphate fertilizer (14 g di-ammonium phosphate per unit weight of nanoclay-polymer composite). Phosphorus loaded nanoclay-polymer composite and conventional diammonium phosphate fertilizer were applied (P dose-40 mg P2O5 kg−1 soil) to two types of soil (Alfisol and Inceptisol). Soil enzyme activity and root volume were studied independently with a factorial completely randomized design experiment. Results revealed that dehydrogenase enzyme activity in modified nanoclay-polymer composite increased by + 26.3 and + 19% over conventional fertilizer in Alfisol and Inceptisol respectively. Acid phosphatase activity (9.25 µg p-nitrophenol g−1 soil h−1) was highest at panicle initiation stage in Inceptisol whereas alkaline phosphatase activity was more at tillering in both soils. Root volume also increased by + 16.8% on applying nanoclay-polymer composite as compared to conventional fertilizer in Alfisol. The corresponding data in Inceptisol was + 13.1%. Therefore, it was concluded that nanoclay-polymer composite prepared from organoclay has a positive effect on soil enzyme activity as well as root volume.

Gamma-induced radiation polymerization of kaolin composite for sorption of lanthanum, europium and uranium ions from low-grade monazite leachate

Gamma radiation polymerization method was used for the modification of kaolin to produce (poly acrylamide-acrylic acid)-Kaolin (PAM-AA-K). Monazite ore is one of the main resources of uranium and lanthanide elements, therefore, this work focused on sorption of uranium, lanthanum and europium ions from low grade monazite leachate. The removal percent for Eu3+, La3+ and UO2 2+ are 94.6, 91.6 and 73.4%, respectively. Monolayer capacity of Eu3+, La3+ and UO2 2+ were found to be 54.64, 45.87 and 37.59 mg/g, respectively. The sorption mechanism of lanthanum and europium ions on PAM-AA-K composite mainly takes place as Ln(OH)2+, and for uranium as uranyl ion, UO2 2+.

Removal of Cs+ and Co2 + ions from aqueous solutions using poly (acrylamide-acrylic acid)/kaolin composite prepared by gamma radiation

Synthesis of poly (acrylamide-acrylic acid)/kaolin composite (P(AM-AA)/K) using gamma radiation was carried out for removal of cesium and cobalt ions from aqueous solution. The prepared composite was characterized using FT-IR, SEM, XRD, TGA and DTA. Comparative adsorption behavior of poly (acrylamide-acrylic acid)/kaolin composite for adsorption of cesium and cobalt ions was studied. The adsorption studies were performed under different pH, temperature, and initial metal ion concentration. The obtained data are handled using adsorption kinetics, isotherm models and the thermodynamic behavior of the metal ion adsorption was calculated. It was found that the synthesized composite possesses a good swelling behavior due to the presence of kaolin. Pseudo-second-order kinetic model provided a better correlation for the experimental data in comparison to the pseudo-first-order kinetic model. The negative value of ΔG indicates the feasibility and spontaneity of the adsorption process. The positive ΔH suggests the endothermic nature of the adsorption.

The synthesis and application of dual temperature/pH-sensitive polymer nanoparticles

ABSTRACTThe monodisperse dual temperature/pH-sensitive nanoparticles are prepared by distillation-precipitation polymerization, which use the acrylic acid (AA) and N-Isopropyl acrylamide (NIPAM) as the monomer materials and divinyl benzene (DVB) as the crosslinking agent. The nanoparticles with excellent stability shows good pH responsiveness and temperature sensitivity that can shrink freely in response to acidic environmental stimuli. The monodisperse nanoparticles may thus be very promising for use in many applications in which rapid responses to dual environmental stimuli are required.

Self‐assembled acrylamide‐based copolymer/surfactant with high‐temperature resistance for enhanced oil recovery

ABSTRACTIn this article, we report on a water‐soluble self‐assembled system that consisted of an acrylamide (AM)‐based copolymer and a nonionic surfactant for enhancing oil recovery. The copolymer, denoted as poly(acrylamide–acrylic acid–diallyl dimethyl ammonium chloride–N‐allyl benzamide) (PMADN), was synthesized with AM, acrylic acid, diallyl dimethyl ammonium chloride, and N‐allyl benzamide, and the nonionic surfactant was Tween 40. The results of our investigation of the ratio of the copolymer to Tween 40 show that the optimal concentrations of PMADN and Tween 40 were 1000 and 500 mg/L, respectively. When it was heated to 115–120 °C for 15 min, the apparent viscosity of the self‐assembly system increased 19.2%, and its viscosity retention rate remained at 11.6% under 1000 s−1. When the system was dissolved in 12,000 mg/L NaCl, 2000 mg/L CaCl2, and 2000 mg/L MgCl2 solutions, the viscosity retention rates were 22.3%, 12.1%, and 17.6%, respectively. In addition, a 2000 mg/L PMADN–Tween 40 solution dramatically enhanced the oil recovery up to 13.4%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45202.