And Acrylamide Research Articles

Graft copolymerization of cellulose acetate for removal and recovery of lead ions from wastewater

In this study, cellulose acetate (CA) was modified by grafting with an equimolar binary mixture of acrylic acid (AA) and acrylamide (AAm) via radical polymerization technique using benzoyl peroxide as an initiator. Comparative studies between CA powder and modified CA [CA-g-(AA-co-AAm)] were investigated for Pb(II) ions removal and recovery from wastewater. The main operating conditions such as pH, concentration of Pb(II) ions and sorbent dose were also studied. Kinetic modeling has been studied and lead uptake capacity was calculated using the Langmuir, Freundlich and Dubinin–Kaganer–Radushkevich (DKR) models. The maximum sorption capacity (qemax) for Pb ions was only 9.4mg/g for unmodified CA, while, it was reached to 66.67mg/g by using modified CA. Spectroscopic analysis (FTIR), SEM, EDX and XRD analysis were investigated for CA and modified CA before and after recovery of lead ions from wastewater.

Swelling kinetics, mechanical properties, and release characteristics of chitosan‐based semi‐IPN hydrogels

ABSTRACTTwo series of pH‐sensitive semi‐interpenetrating network hydrogels (semi‐IPN) based on chitosan (CS) natural polymer and acrylamide (AAm) and/or N‐hydroxymethyl acrylamide (HMA) monomers by varying the monomer and CS ratios were synthesized by free radical chain polymerization. 5‐Fluorouracil (5‐FU), a model anticancer drug, has been added to the feed composition before the polymerization. The characterization of gels indicated that the drug is molecularly dispersed in the polymer matrix. The swelling kinetics of drug‐loaded gels have decreased with increased HMA content at 37°C in both distilled water and buffer solutions with a pH of 2.1 or 7.4. Elastic modulus of the gels increased with the increase in HMA content and higher CS concentration enhanced the elastic modulus positively. Moreover, cumulative release percentages of the gels for 5‐FU were ca. 10% higher in pH 2.1 than those in pH 7.4 media. It was determined that they can be suitable for the use in both gastric and colon environments. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41886.

Preparation and adsorption characteristics of surface-imprinted polymer using bovine serum albumin and lysozyme as double template proteins

The double template surface-imprinted polymer (Bi-MIP)) was synthesized by atom transfer radical polymerization (ATRP) in aqueous media, using bovine serum albumin (BSA) and lysozyme (Lyz) as the template prteis, X-isopropylacrylamide (NIPAAm) and acrylamide (AAm) as the monomers and X-3-(dimethylamino) propyl-methacrylamide (DMAPMA) as the assistant of basic functional monomner. The ATHP possessed the mild reaction conditions and can be initiated at room temperature without heating and ultraviolet radiations. The preparation conditions of imprinted polymer were optimized, and the content of DMAPMA as the assistant of basic functional monomer was investigated. The results showed that Bi-MIP exhibited the good adsorption capacity and selectivity in single protein solution and in mixed protein solution when the volume of DMAPMA in the preparation process of Bi-MIP was 20 µL. The rebinding capacity of Bi-MIP was evaluated according to adsorption isotherm of the imprinted polymer. The Langmir adsorption model was employed to describe the isotherms and revealed that Bi-MIP exhibited the maximum rebinding to 13SA and Lyz at 10.2 mg g and 19.2 mg/g, respectively. And Bi-MIP had good imprinting effect and adsorption capacity to templates BSA and Lyz from egg white and bovine serum samples. This will provide a new way for specific recognition of the double multiple target proteins in the complex biological samples.

Liquid crystalline behavior of graphene oxide in the formation and deformation of tough nanocomposite hydrogels.

In this paper, we report the formation and transformation of graphene oxide (GO) liquid crystalline (LC) structures in the synthesis and deformation of tough GO nanocomposite hydrogels. GO aqueous dispersions form a nematic LC phase, while the addition of poly(N-vinylpyrrolidone) (PVP) and acrylamide (AAm), which are capable of forming hydrogen bonding with GO nanosheets, shifts the isotropic/nematic transition to a lower volume fraction of GO and enhances the formation of nematic droplets. During the gelation process, a phase separation of the polymers and GO nanosheets is accompanied by the directional assembly of GO nanosheets, forming large LC tactoids with a radial GO configuration. The shape of the large tactoids evolves from a sphere to a toroid as the tactoids increase in size. Interestingly, during cyclic uniaxial tensile deformation a reversible LC transition is observed in the very tough hydrogels. The isolated birefringent domains and the LC domains in the tactoids in the gels are highly oriented under a high tensile strain.

Hydrogel diffraction grating as sensor: A tool for studying volume phase transition of thermo-responsive hydrogel

Hydrogel diffraction gratings were developed as a sensing tool to study volume phase transition of thermo-responsive hydrogels. The gratings were fabricated from hydrogels mainly consisted of N-isopropylacrylamide (NIPAAm) and acrylamide (AAm) as monomer units, in some cases, acrylic acid (AA) as well. The hydrogel diffraction gratings were prepared through photoinscribing, soft-lithographic duplication, micro-contact printing and photopolymerization/crosslinking of the monomers. Surface-relief-gratings (SRGs) on azo polymer films were inscribed by interfering Ar+ laser beam irradiation and used as grating masters. Poly(dimethylsiloxane) (PDMS) elastomer stamps were prepared through replica molding by casting the prepolymer on the SRGs and curing. The diffraction grating sensors were obtained by contact printing and photopolymerization/crosslinking under UV light irradiation. The variation of the first order diffraction efficiency (DE1) of the gratings was measured as a function of temperature to detect the transition temperatures of the hydrogels. The swelling ratios of the hydrogels were semi-quantitatively correlated with the DE1/DE10 ratio. The methodology was used to study the effects of cross-linker content, monomer ratio and solution pH on transition temperature and swelling ratio. The hydrogel diffraction gratings show ability to sense the volume phase transition in a real-time way and can be used for studying thermo-responsive hydrogels.

Preparation and mechanical properties of a transparent ionic nanocomposite hydrogel

The poor stability of clay dispersion in the presence of ionic species presents a challenge for preparing a transparent ionic nanocomposite (NC) hydrogel with the desired strength. A transparent ionic NC hydrogel was successfully prepared by in situ copolymerization of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylamide (AAm) in the Laponite dispersion. AMPS played a dominant role in the dispersion of Laponite. Mechanical analyses demonstrated that this type of hydrogel has a combination of high tensile strength and excellent stretch ability. An increase in AMPS content made a big contribution to the tensibility, while an increase in clay content improved the elastic modulus. The ionic NC hydrogel exhibited a self-healing property, which occurred autonomously, without any outside intervention. The results showed that physical interaction among the NC hydrogels can be recovered. This work is a continuation of our previous efforts on the preparation and application of ionic NC hydrogels, for which there is a range of potential applications in soft and smart machines in the future.

Application of vinyl monomers functionalized cellulosic biopolymer for removal of dissolved toxic metal ions from polluted water samples

In the present study, a binary vinyl monomer mixture of acrylonitrile (AN) and acrylamide (AAm) was graft copolymerized onto cellulosic fibers using ascorbic acid and hydrogen peroxide as redox initiator. The grafted fibers were further reacted with aqueous solution of hydroxylamine hydrochloride at pH 10.0 to convert them into amidoxime derivative. These resulting functionalized cellulosic fibers were characterized by various techniques such as FT-IR, TGA, and SEM studies. The functionalized fibers were used for removal of toxic metal ions from aqueous solution through adsorption process. The adsorption process follows pseudo-second-order kinetics and relative adsorption rate of various metal ions were found in the order of Pb2+>Zn2+>Cd2+. Langmuir, Freundlich and Dubinin–Radushkevich models were used to show the adsorption isotherm. Langmuir model fits better with the equilibrium data. The maximum monolayer capacity qm calculated using the Langmuir isotherm for Zn2+, Cd2+ and Pb2+ metal ions were 55.72, 106.72 and 200mg/g respectively. From thermodynamic parameters ΔH° and ΔG° values were obtained. The adsorption process has been found to be exothermic in nature.

Deconstructing the Double-Network Hydrogels: The Importance of Grafted Chains for Achieving Toughness

This paper aims to shed light on the microstructure of tough, “double-network” (DN) hydrogels synthesized by free-radical polymerization of a monomer within a highly cross-linked polyelectrolyte hydrogel and to discuss the most efficient topological microstructure for toughness enhancement. Fourier transform infrared (FTIR) characterization of a hydrogel synthesized from the potassium salt of 3-sulfopropyl acrylate (SAPS) and 2-hydroxyethyl acrylate (HEA) demonstrated that polymer chains synthesized during the second polymerization step of a conventional DN hydrogel are grafted to the skeleton of the polyelectrolyte network. Uniaxial tensile tests performed on hydrogels synthesized from SAPS and acrylamide (AAm) indicate that linear and nonlinear polymerization of a second monomer within a network without grafting to the first network, i.e., forming a semi-interpenetrating or interpenetrating network, does not produce a tough hydrogel. Toughness enhancement of a covalent hydrogel was optimized by grafting...

Synthesis and Characterization of Porous Hydrogel Based on Lignin and Polyacrylamide

A porous lignin-containing hydrogel was developed for dye removal via graft copolymerization of acetic acid lignin (AAL) and acrylamide (AAm), in the presence of ethyleneglycol dimethacrylate (EGDMA) as a crosslinker and H2O2 as an initiator. AAL was characterized by FT-IR and TGA. After being washed to remove impurities, the hydrogel was characterized by FT-IR, TGA, SEM, and swelling ratio. FT-IR spectra suggested that AAL was present in the hydrogel. The TGA curves revealed that the introduction of AAL had no significant impact on the thermal stability of PAAm. SEM images showed that the honeycomb-like structure of the hydrogel was improved with increasing AAL content. The swelling ratio data showed that the hydrogel with a high AAL/AAm ratio was sensitive to pH. Furthermore, increased lignin content of the hydrogel favors the dye adsorption.

Microwave promoted synthesis of smart superporous poly (dimethylaminoethyl methacrylate-co-acrylamide) hydrogels and study of Kamlet-Abboud-Taft polarity functions for obtained materials

Smart Superporous hydrogels (SPHs) of dimethylaminoethyl methacrylate (DMAEMA) and acrylamide (AAm) under various conditions were synthesized via microwave (MW) procedure. The synthesized SPHs were confirmed by Fourier Transform spectroscopy (FT-IR). It was demonstrated that increasing feeding ratios of crosslinker and increasing irradiation time in the hydrogels the corresponding peaks became stronger. The X-Ray Diffraction (XRD) spectra was shown the amorphous nature of hydrogels and Scanning Electron Microscopy (SEM) micrographs of the freeze-dried poly(DMAEMA-co-AAm) hydrogels showed honeycomb-like pores. The thermal degradation behavior of obtained SPHs was investigated by Thermalgravimetery analysis (TGA). According to TGA results, hydrogels showed a higher thermal stability with increasing in irradiation time, which could be due to the higher crosslinking degree within the networks. Furthermore, some parameters such as pH, irradiation time and crosslinking content on the swelling behavior of SPHs samples were studied. Finally, the Kamlet-Abboud-Taft polarity functions obtained with polarity standard probe for all synthetic smart SPHs media.

Using of Novel Halides in the ATRP Polymerization. Estimation of Polymer Molecular Mass

SummaryTwo novel ATRP initiator (R‐X): 2‐bromo‐2‐methyl‐N‐(1‐phenyl‐ethyl)propanamide (I) and 2,2,2‐trichloro‐N‐(1‐phenylethyl)acetamide (II) were synthesized and characterized by 1H‐NMR, IR, EI. Also, crystal structures of (I) and (II) are reported. Compounds (I) and (II) were used in the ATRP reaction of methyl methacrylate (MMA) and acrylamide (AAD) at 48°C, using CuBr/Me6TREN and ethanol/toluene (60:40) mixture as catalytic complex and solvent, respectively. End‐group analysis by 1H‐NMR was used to determinate the molecular mass of the polymers synthesized via ATRP. The Mn values for poly(MMA) using (II) were 2333 and 3952 g/mol, which is higher in comparison with the Mn values obatined for (AAD)/(II) and (AAD)/(I) systems indicating that monomers containing ester moiety in their structure, such as acrylates and methacrylates, may be good candidates to polymerize with (II) and CuBr/Me6TREN.

The preparation of magnetic molecularly imprinted nanoparticles for the recognition of bovine hemoglobin

The protein imprinted technique combining surface imprinting and nano-sized supports materials is an attractive strategy for protein recognition and rapid separation. In this work, we imprinted bovine hemoglobin (BHb) on magnetic nanoparticles. With itaconic acid (IA) and acrylamide (AAm) as the monomers, the experiment was carried out in aqueous media via surface-imprinting technique. The effects of initial concentration and adsorption time over the adsorption capacity of both imprinted and non-imprinted nanoparticles were analyzed. The maximum adsorption capability of imprinted nanoparticles was found to be 77.6 mg g(-1), which was 3.1-4.3 times higher than that of the non-imprinted nanoparticles prepared at the same conditions. This resulted in the successful formation of imprinting cavities. Moreover, in selective adsorption experiment and competitive batch rebinding test, imprinted nanoparticles exhibited a high specific recognition of the template protein over the non-imprinted protein.

Synthesis and characterization of interpenetrating polymer network of polyglycidyl methacrylate and acrylamide using selenonium ylide as an initiator

Interpenetrating polymer network (IPN) based on polyglycidylmethacrylate (PGMA) and acrylamide (AAm) was synthesized using divinylbenzene (DVB) as a crosslinking agent and diphenylselenonium 2, 3, 4, 5-tetraphenylcyclopentadienylide (selenonium ylide) as a new radical initiator. A series of IPNs were prepared by varying the concentrations of AAm, PGMA, DVB and selenonium ylide in dioxan for 90 min at 80 ± 1 °C under an inert atmosphere of nitrogen. Dual phase morphology of the synthesized IPN was revealed by scanning electron microscopy (SEM). The properties like percentage swelling, average molecular weight of network between crosslinks (Mc) and young’s modulous were direct function of linear polymer [PGMA] and initiator [Ylide] where as inverse function of monomer [AAm] and crosslinker [DVB]. The differential scanning calorimetry (DSC) curve showed glass transition temperature at 127 °C. The synthesized IPN is thermally stable up to 450 °C. FTIR, 1H NMR and 13C NMR spectroscopic techniques were used for characterization of polyglycidylmethacrylate and IPN of polyglycidylmethacrylate (PGMA) and acrylamide (AAm). FTIR spectrum confirmed the presence of PGMA, AAm and DVB in the formed IPN by showing their characteristic bands. Similarly, 1H NMR and 13C NMR spectrum of the synthesized IPN also exhibit all characteristic peaks of PGMA, AAm and DVB in the formed IPN.

Rhodamine based reusable and colorimetric naked-eye hydrogel sensors for Fe3+ ion

In this study, N-(Rhodamine-6G)lactam-N′-acryloyl-ethylenediamine (RH6GAC) as co-monomer was synthesized in two steps and characterized by FT-IR, 1H, 13C NMR and mass spectrometry. Metal ion (Na+, K+, Ca2+, Fe2+, Fe3+,Co2+, Ni2+, Cu2+, Zn2+, Pb2+, Cd2+, Hg2+, Mn2+, Ba2+, Mg2+) selectivity of RH6GAC was investigated by UV–Vis and fluorescence spectrophotometry. Then, Fe3+ ion selective and reusable naked-eye colorimetric copolymeric sensor hydrogels were synthesized using 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) as the primary monomer and N-(Rhodamine-6G)lactam-N′-acryloyl-ethylenediamine as comonomer by free radical polymerization. The sensor hydrogel was characterized by FT-IR and swelling properties.

On the Necking Phenomenon in Pseudo-Semi-Interpenetrating Double-Network Hydrogels

A detailed physical picture of necking phenomenon in semi-interpenetrating double-network (SIDN) hydrogels was developed using the tensile mechanics of DN hydrogels synthesized from 3-sulfopropyl acrylate potassium salt (SAPS) and acrylamide (AAm) with different molecular weights. Uniaxial tensile tests for DN hydrogels already damaged by a compression load demonstrated the necking required a first network with a brittle structure. Although necking originates from the brittle nature of the first network, the molecular weight of polymer chains of the second network is an important factor for neck propagation. The finite deformation of DN hydrogels is characterized by two regimes of deformation: one where the neck initiates and a second where it propagates.

Multiwalled Carbon Nanotubes and NaYF4:Yb3+/Er3+ Nanoparticle-Doped Bilayer Hydrogel for Concurrent NIR-Triggered Drug Release and Up-Conversion Luminescence Tagging

Bilayer thermosensitive P(NIPAm-co-AAm) hydrogel discs were prepared by a facile UV light initiation process from N-isopropylacrylamide (NIPAm) and acrylamide (AAm) monomers' cross-linking copolymerization. Poly(ethylene glycol) (PEG) as a pore-forming agent was added in order to form a porous structure and improve the water content in the hydrogel. Functional materials of NaYF4:Yb(3+)/Er(3+) nanoparticles and multiwalled carbon nanotubes (MWCNTs) were incorporated into different layers of the P(NIPAm-co-AAm) hydrogel for the purpose of up-conversion luminescence labeling and the NIR light antenna effect, respectively. Significantly improved drug release from composite hydrogels was achieved in response to 980 nm NIR light irradiation by using lysozyme as a macromolecular drug. The multifunctional hydrogel reported here provides a platform for simultaneous NIR luminescence labeling and NIR-driven drug release.

Enhancing antifouling capability of PES membrane via mixing with various types of polymer modified multi-walled carbon nanotube

Acid functionalized multi-walled carbon nanotube (MWCNT) was modified by three hydrophilic polymers during an in situ polymerization reaction. Citric acid (CA), acrylic acid (AA) and acrylamide (AAm) were polymerized on functionalized MWCNTs to achieve greater number of functional groups on MWCNTs. Fourier transform infrared spectroscopy (FTIR) validated the formation of hydroxyl, carboxyl and amide groups on MWCNTs. Mixed matrix membranes were prepared by introducing 0.1wt% of acid functionalized and polymer modified MWCNTs into polyethersulfone (PES) membranes. Water permeability and antifouling capability of prepared membranes were compared. According to the results, mixed matrix membranes showed higher pure water flux compared to pristine PES membrane. Hydrophilicity of polymer modified MWCNT/PES nanocomposite membrane was improved for all three polymers. The results indicated that hyperbranched polycitricacid (PCA) on MWCNTs offered large number of functional groups and significantly improved membrane fouling resistance against whey proteins. Efficient dispersion of PCA modified MWCNT in casting solution led to smooth and hydrophilic membrane surface and consequently higher flux recovery ratio (95%). Existence of PCA dendrimers on MWCNT increased the carbon nanotubes compatibility with membrane bulk polymer and resulted in superior dispersion of nanofiller in membrane matrix and its surface. The morphology and surface characteristics of prepared membrane were investigated by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and water contact angle (WCA) measurement.

Smart surface imprinting polymer nanospheres for selective recognition and separation of glycoprotein

Through covalent immobilization of template and surface imprinting, smart molecularly imprinted polymer nanospheres were developed for selective separation of the glycoprotein ovalbumin (OB). First, a boronic acid group-bearing poly (methyl methacrylate) (b-PMMA) nanosphere was synthesized directly at the high temperature of 70°C. The b-PMMA nanosphere could pre-immobilize the template OB on its surface by forming reversible covalent bonds. Then the precipitation polymerization of N-isopropylacrylamide (NIPAAm) and acrylamide (AAm) readily occurred on the b-PMMA nanosphere as a core at room temperature, leading to the formation of core–shell molecular imprinting nanosphere. The experiments showed the rebinding affinity of the imprinted nanospheres was thermo- and pH-dependent. The resulting imprinted nanospheres showed high adsorption capacity and good specific recognition behavior toward the template molecule, and no obvious reusability deterioration was observed. Most notably, the imprinted nanospheres reached saturated adsorption within 20min, indicating faster rebinding kinetics. In addition, the imprinted nanospheres were successfully applied to selectively separate the target OB from an egg white sample.

Functionalization of polyethylene by graft copolymerization for separation processes

Incorporation of polar functional moieties into polyethylene (PE) film has been achieved by graft copolymerization of polar monomers such as methacrylic acid (MAAc) and acrylamide (AAm) on to PE film, preirradiated with γ-rays from 60 Co source, using benzoyl peroxide (BPO) as initiator in aqueous medium. Percentage of grafting of MAAc and AAm was determined as a function of irradiation dose, monomer and initiator concentration, temperature, reaction time and amount of water. Maximum percentage of grafting of MAAc (1453%) and AAm (21.28%) was obtained at (MAAc) = 235.3 x 10 -2 mol/L, (AAm) = 23.4 x 10 -2 mol/L, (BPO) = 5.5 x 10 -2 mol/L and 16.5 x 10 -2 mol/L at 80°C, 90°C in 180 min and 90 min respectively. The grafted PE films were characterized by FTIR, Thermogravimetric analysis (TGA) Scanning Electron Micrography (SEM) and X-ray diffraction methods. Some selective properties of grafted films such as swelling behavior, ion and metal uptake have been carried out. The biodegradation studies of the grafted PE films have also been investigated. The grafted films developed superior swelling behavior with maximum swelling (480%) in water as compared to pristine PE (13.55%), better thermal stability and ion and metal uptake studies showed promising results that can be effectively used for desalination of brackish water and separation of metals from the industrial effluents.

Photoisomerization of Provitamin D in Hydrogel Matrix

Study of interfacial processes between incorporated biomolecules and hydrogel matrix is of primary importance for the application of synthetic hydrogels as biomaterials, sensors, etc. Their hydrophilic nature, however, hampers fat-soluble biomolecule incorporation. We synthesized N-isopropylacrylamide (NIPAAm)- and Acrylamide (AA)-based hydrogels with hydrophilic-lipophilic balance that under specific conditions permit homogeneous incorporation of provitamins D3(7-dehydrocholesterol) and D2(ergosterol) dissolved in ethanol. Similarity of provitamins D photoisomerization in such hydrogel matrices with the photoreaction in ethanol shows great potential of the novel material for personal dosimetry of biologically active ‘antirachitic’ UV radiation.