Nanocomposite Gel Research Articles

Poly(N,N-dimethylacrylamide)-clay nanocomposite hydrogels with patterned mechanical properties

Poly(N,N-dimethylacrylamide)-clay nanocomposite gels (NC gels) with patterned network-chain density were prepared by photoinitiated radical polymerization with photomasks. The exposed region of the obtained gels showed a higher swelling ratio and lower elastic modulus than the masked region, although these regions had the same weight composition. A stripe-patterned gel prepared using a photomask with many slits of several hundred micrometers wide exhibited mechanical anisotropy: the elastic modulus in the direction parallel to the slits was higher than that in the perpendicular direction.

Zinc ion conducting blended polymer electrolytes based on room temperature ionic liquid and ceramic filler

ABSTRACTZinc ion conducting nanocomposite gel polymer electrolytes (NCGPEs) comprising of poly(vinyl chloride) (PVC)/poly(ethyl methacrylate) (PEMA) blend, zinc triflate [Zn(OTf)2] salt, 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) ionic liquid (IL) and fumed silica (SiO2) viz. [PVC/PEMA–Zn(OTf)2–EMIMTFSI–SiO2] exhibited the highest ionic conductivity value of 6.71 × 10−4 Scm−1 at room temperature. The ion–filler–polymer interactions and probable conformational changes observed in the structure of the gel composites due to the entrapment of IL and dispersion of nano‐sized SiO2 were confirmed from X‐ray diffraction (XRD) and Attenuated total reflection‐Fourier transform infrared (ATR‐FTIR) spectroscopy. Scanning electron microscopic (SEM) images of NCGPEs demonstrated uniform surface with abundant interconnected micropores. The cationic transport number of NCGPE samples has been found to be appreciably enhanced up to a maximum of 0.69 thus demonstrating a considerable improvement in Zn2+ ion conductivity. The NCGPE film possesses an electrochemical stability window up to 5.07 V (vs. Zn/Zn2+) and ensures feasible zinc stripping/plating in the redox process. The addition of SiO2 into the gel polymer electrolyte system has effectively reduced the glass‐transition temperature (Tg) of the NCGPE films and also accomplished improved thermal stability up to approximately 180 °C which were ascertained from Differential scanning calorimetry (DSC) and Thermogravimetric (TG) results. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47654.

New approach to electron microscopy imaging of gel nanocomposites in situ

Characterization of Au-nanocomposites is routinely done with scattering techniques where the structure and ordering of nanoparticles can be analyzed. Imaging of Poloxamer gel-based Au-nanocomposites is usually limited to cryo-TEM imaging of cryo-microtomed thin sections of the specimen. While this approach is applicable for imaging of the individual nanoparticles and gauging their size distribution, it requires altering the state of the specimen and is prone to artifacts associated with preparation protocols. Use of Scanning Transmission Electron Microscopy (S/TEM) with fluid cell in situ provides an opportunity to analysis of these complex materials in their hydrated state with nanometer resolution, yet dispensing dense gel-based samples onto electron-transparent substrates remains challenging. We show that Poloxamer gel-based Au nanocomposites exhibiting thermoreversible behavior can be imaged in a fully hydrated state using a commercially available fluid cell holder, and we describe a specimen preparation method for depositing femtoliter amounts of gel-based nanocomposites directly onto the 50 nm-thick SiN window membranes. Ultimately, fluid cell S/TEM in situ imaging approach offers a pathway to visualization of individual nanoparticles within a thick gel media while maintaining the hydrated state of the carrier polymeric matrix.

Green synthesis of silver-chitosan nanocomposite and their application as antibacterial material

It has been studied green synthesis of silver-chitosan nanocomposite using chitosan as a reducing agent as well as a stabilizing agent and NaOH accelerator. This research develops a new strategy for preparation silver-chitosan nanocomposite through gel phase. The silver-chitosan nanocomposite gel is transformed into colloidal by dissolving into chitosan solution. Localized surface plasmon resonance (LSPR) phenomenon of the colloidal silver nanoparticles were investigated using a UV-Vis spectrophotometer. The shape and size of the nanoparticle silver were analyzed using Transmission Electron Microscopy (TEM). Antibacterial activity test of silver-chitosan nanocomposite against E. coli and S. aureus bacteria by disc diffusion method. The formation of silver nanoparticles in the synthesis of silver nanocomposite-chitosan chitosan through the gel phase is characterized by the appearance of LSPRabsorption peak at 402.4 - 414.5 nm. The optimum conditions of silver-chitosan nanocomposite formation were the use of chitosan (1%) of 60 mL, AgNO3 0.07 mmol, NaOH 7 mmol within 18 hours. Based on TEM image of spherical particles with dominated at particle size between 5 - 11 nm. The antibacterial activity of silver-chitosan nanocomposite is high enough that it is potentially used as an antibacterial material for medical applications.

Thermosensitive nanocomposite gel for intra-tumoral two-photon photodynamic therapy

We propose here a new approach to achieve intratumoral near-infrared (NIR) two-photon photodynamic therapy (PDT). We established a composite micellar thermosensitive hydrogel made of clinically approved methoxy poly(ethylene glycol)-polylactide copolymer (mPEG-PDLLA) and Pluronic (F127). The mPEG-PDLLA form micelles that can be loaded with two-photon absorption compound (T1) and photosensitizer (PS), The F127 micelles are liquid at room temperature and while forming an hydrogel at body temperature. This enables an in situ gelification upon injection providing long-term retentio within the tumor. The NIR light is thus upconverted into visible light by T1 and excited PS. The morphology, rheology properties and releasing profiles of hydrogel were fully characterized. The rheology properties and releasing mechanism was investigated. The composite hydrogel showed significant cytotoxicity to 4 T1 murine breast cancer cells upon NIR laser irradiation, while it showed non-significant cytotoxicity without. Time-dependent in vivo and ex vivo distribution results suggested that hydrogel administrated via intra-tumoral injection could prolong both PDT agents retention in tumor. We show here that the use of NIR radiation allows deep tissue penetration and inhibition of tumor growth of >50% even under 1 cm thick muscle tissue.

Mimicking Dynamic Adhesiveness and Strain-Stiffening Behavior of Biological Tissues in Tough and Self-Healable Cellulose Nanocomposite Hydrogels.

Although self-healing gels with structural resemblance to biological tissues attract great attention in biomedical fields, it remains a dilemma for combination between fast self-healing properties and high mechanical toughness. On the basis of the design of dynamic reversible cross-links, we incorporate rigid tannic acid-coated cellulose nanocrystal (TA@CNC) motifs into the poly(vinyl alcohol) (PVA)-borax dynamic networks for the fabrication of a high toughness and rapidly self-healing nanocomposite (NC) hydrogel, together with dynamically adhesive and strain-stiffening properties that are particularly indispensable for practical applications in soft tissue substitutes. The results demonstrate that the obtained NC gels present a highly interconnected network, where flexible PVA chains wrap onto the rigid TA@CNC motifs and form the dynamic TA@CNC-PVA clusters associated by hydrogen bonds, affording the critical mechanical toughness. The synergetic interactions between borate-diol bonds and hydrogen bonds impart a typical self-healing behavior into the NC gels, allowing the dynamic cross-linked networks to undergo fast rearrangement in the time scale of seconds. Moreover, the obtained NC hydrogels not only mimic the main feature of biological tissues with the unique strain-stiffening behavior but also display unique dynamic adhesiveness to nonporous and porous substrates. It is expected that this versatile approach opens up a new prospect for the rational design of multifunctional cellulosic hydrogels with remarkable performance to expand their applications.

PVC/PEMA‐based blended nanocomposite gel polymer electrolytes plasticized with room temperature ionic liquid and dispersed with nano‐ZrO2 for zinc ion batteries

Nanocomposite gel polymer electrolytes (NCGPEs) comprising of the solution of zinc trifluoromethanesulfonate [Zn(OTf)2] in 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) ionic liquid entrapped in poly(vinyl chloride)/poly(ethyl methacrylate) blend and dispersed with zirconia (ZrO2) nanofiller has been prepared via simple solution casting method. The free standing film of the composite gel polymer electrolyte system exhibited the maximum room temperature ionic conductivity of 3.63 × 10−4 Scm−1 at 3 wt% nanofiller concentration with the accomplishment of highest zinc ion transference number of 0.66. The interaction and complexation among various constituents of the resultant NCGPEs has been confirmed from X‐ray diffraction (XRD) and Attenuated total reflection‐Fourier transform infrared (ATR‐FTIR) spectroscopic studies. Differential scanning calorimetry (DSC) and thermogravimetric (TG) analyses further corroborates the improved thermal behavior of ZrO2 added gel polymer electrolytes as compared with that of filler‐free gel electrolytes. The porous morphology of the thin films was observed by scanning electron microscopy (SEM) whereas the electrochemical properties of the NCGPEs were studied utilizing linear sweep voltammetry (LSV) and cyclic voltammetry (CV). POLYM. COMPOS., 40:3402–3411, 2019. © 2019 Society of Plastics Engineers

Development of fly ash reinforced nanocomposite preformed particle gel for the control of excessive water production in the mature oil fields

One of the appropriate methods to minimize water production and increase sweep efficiency is the utilization of Preformed Particle Gel (PPG) in the mature oil fields. In this paper, a new fly ash reinforced nanocomposite PPG was developed by the reaction of acrylamide as monomer, N,N′-Methylenebis (acrylamide) as crosslinker and nano fly ash in presence of Potassium Persulfate as initiator and it was compared with a conventional PPG which was designed without nano fly ash. On the incorporation of nano fly ash, swelling performance and thermal stability of PPG had increased significantly. Rheological data revealed that dynamic moduli (G′ and G″) of fly ash reinforced nanocomposite PPG has improved viscoelastic properties with a higher value of critical shear stress as compared to conventional PPG. The single sandpack flow experiment has shown the injectivity of nanocomposite PPG into the sandpack with a maximum resistance factor of 60.57. However, parallel-sandpack flow experiment showed that the newly developed nano fly ash reinforced nanocomposite PPG has a profile improvement rate of 92.98% and 97.83% for the permeability contrast of 2.16 and 4.14 respectively and hence it may be a promising agent in reducing excessive water production in mature oil fields.

A versatile strategy for mechanically durable nanocomposite cryogels based on cationic (alkyl)methacrylates and hydrophilic bentonite via freezing (cryo)polymerization.

A simple strategy for the preparation of organic-inorganic (alkyl)methacrylate-based nanocomposite gels was established. The preparation procedure was based on free-radical copolymerization of cationic monomer N,N-dimethylaminoethyl methacrylate (DMAEMA) in the presence of a low amount of ionic comonomer 2-acrylamido-2-methyl-propanosulfonic acid (AMPS), nanoclay bentonite (BENT) and diethyleneglycol dimethacrylate (DEGDMA) as a chemical crosslinker. The parameters of equilibrium volume swelling, initial swelling rate, diffusional exponent, and early- and late-time diffusion coefficients were evaluated from the swelling measurements in salt solutions. PDMAEMA retained its own characteristics regardless of the amounts of ionic comonomer AMPS and nanoclay bentonite. The prepared nanocomposite cryogels/hydrogels were found to be pH and temperature-responsive. The elastic moduli and compressibility of the nanocomposite NC/BENTm-Cgels were much higher than those of NC/BENTm-Hgels. The effective crosslink density distribution of the nanocomposite NC/BENTm-Hgels was evaluated from the elastic moduli data of the as-prepared state and the degree of crosslinking was described by a quadratic polynomial as a function of the clay concentration. At high clay content, the nanocomposite NC/BENTm gels exhibited a lower swelling degree, and thus a higher crosslinking density than the clay-free gels. Both NC/BENTm Hgels and Cgels exhibited obvious pH and temperature double sensitiveness; the equilibrium degree of swelling decreased as the solution's pH or the swelling temperature increased. The power law exponent values obtained from dynamic swelling in aqueous Na2SO4 solution indicated that the sorption mechanism of both the nanocomposite NC/BENTm-Hgel and NC/BENTm-Cgel samples was Fickian controlled. Overall, this study successfully establishes the thermodynamic relations between the physico-mechanical behavior and characteristic network parameters of (alkyl)methacrylate-based nanocomposite gels prepared at various BENT concentrations.

Structural and Conductivity Studies of PAN-based Al2O3 Nano Composite Gel Polymer Electrolytes

Structural and Conductivity Studies of PAN-based Al2O3 Nano Composite Gel Polymer Electrolytes

Smart Shear-Thinning Hydrogels as Injectable Drug Delivery Systems.

In this study, we fabricated and characterized a smart shear-thinning hydrogel composed of gelatin and laponite for localized drug delivery. We added chitosan (Chi) and poly N-isopropylacrylamide-co-Acrylic acid (PNIPAM) particles to the shear-thinning gel to render it pH-responsive. The effects of total solid weight and the percentage of laponite in a solid mass on the rheological behavior and mechanical properties were investigated to obtain the optimum formulation. The nanocomposite gel and particles were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), zeta potential, and dynamic light scattering techniques. Finally, release related experiment including degradability, swelling and Rhodamine B (Rd) release at various pH were performed. The results suggest that incorporation of silicate nanoplatelets in the gelatin led to the formation of the tunable porous composite, with a microstructure that was affected by introducing particles. Besides, the optimum formulation possessed shear-thinning properties with modified rheological and mechanical properties which preserved its mechanical properties while incubated in physiological conditions. The release related experiments showed that the shear-thinning materials offer pH-sensitive behavior so that the highest swelling ratio, degradation rate, and Rd release were obtained at pH 9.18. Therefore, this nanocomposite gel can be potentially used to develop pH-sensitive systems.

Effect of cellulose nanocrystals on the performance of drug loaded in situ gelling thermo-responsive ophthalmic formulations

Triblock poloxamer copolymer (PM) has been extensively utilized to deliver various ophthalmic pharmaceutical compounds. The aim of efficient ophthalmic drug delivery strategy is to attain the longer precorneal resident time and good bioavailability of drugs. In this pursuit, the influence of cellulose nanocrystals (CNC) on the in situ gelation behavior of PM and in vitro release of pilocarpine hydrochloride from the nanocomposites formulations was studied. The critical concentration of gelation of PM being 18% (wt/v) was dropped to 16.6% (wt/v) by the addition of a very low percentage of CNC. The reinforcing nature of CNC via H-bonding in the in situ nanocomposite gel also led to an increase in gel strength along with the sustained release of loaded drugs when compared with the pure PM gel. All formulations revealed that the drug release mechanism is controlled by the Fickian diffusion. Thus, the CNC has a significant effect on the gelation behavior, gel strength, and drug release kinetics of PM-CNC formulations.

Porous nanocomposite gel polymer electrolyte with high ionic conductivity and superior electrolyte retention capability for long-cycle-life flexible zinc–air batteries

Zinc–air batteries (ZABs) with high energy density and low cost have ignited tremendous interest in meeting the ever-growing demands for flexible and portable electronics. As the “blood” of a flexible ZAB, the semi-solid/solid-state electrolyte plays a critical role in the battery performance such as cycling performance, rate characteristics and power output. Herein, a novel porous-structured poly (vinyl alcohol) (PVA)-based nanocomposite gel polymer electrolyte (GPE) with the optimum addition of silica (SiO2) was synthesized and utilized in a bendable sandwich-type ZAB. The fabricated porous PVA-based nanocomposite GPE exhibited a high ionic conductivity (57.3 mS cm–1), excellent water retention capability as well as improved thermal and mechanical properties under ambient condition, with which the assembled flexible ZAB presented excellent cycle stability, discharge performance and power density. Furthermore, the flexible porous PVA–SiO2 based ZAB sets could power a light-emitting diode screen, a handheld electric fan, or even a mobile phone, demonstrating its promising potential for high-performance ZABs with high safety, cost-effectiveness, and excellent flexibility.

Performance evaluation of a new nanocomposite polymer gel for water shutoff in petroleum reservoirs

A new polymer gel nanocomposite is fabricated for excess water production control (water shut off) in petroleum reservoirs and its rheological behavior is evaluated in the presence of sea water and formation water at the temperature of 100 °C. It is shown that at a high salinity without using SiO2 nanoparticles, the elastic modulus of synthesized polymer gel in the presence of sea water and formation water are 12.5 Pa and 9.8 Pa respectively. However by incorporation of SiO2 nanoparticles in the polymer gel matrix, the elastic modulus of synthesized polymer gel in the presence of sea water and formation water can be improved to 13.56 Pa and 11.57 Pa respectively, which is quite interesting from reservoir engineering viewpoint. Equilibrium Swelling Ratio (ESR) of the nanocomposite polymer gel in sea water and formation water decreases as the concentration of the SiO2 increases. Thermal stability of the polymer gel is investigated by differential scanning calorimetry (DSC) measurements. The inflexion temperature of the polymer gel is improved by incorporation of 2000 ppm SiO2 nanoparticles. The fabricated polymer gel nanocomposite in this work can have potential application in reduction of excess water production during enhanced oil recovery (EOR) operations in petroleum industry.

Investigations of Zinc Ion Dissociation in Gel Polymer Electrolytes Based on Poly(vinyl chloride) and Poly(ethyl methacrylate) Blend on the Addition of Two Different Ceramic Nanofillers

Two series of nanocomposite gel polymer electrolytes (NCGPEs) have been prepared by simple solution casting method comprising of chosen nano-sized ceramic fillers [Alumina (Al2O3), Titania (TiO2)] dispersed into [poly(vinyl chloride) (PVC)/poly(ethyl methacrylate) (PEMA)] blend-based gel doped and plasticized with zinc triflate [Zn(OTf)2] salt and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) ionic liquid. The role of various concentrations of two different inorganic nanofillers on the structural and complex formation of the gel polymer electrolytes (GPEs) were explored from X-ray diffraction (XRD), Attenuated total reflection-Fourier transform infrared (ATR-FTIR) and differential scanning calorimetric (DSC) analyses, respectively. All the composite electrolyte films were subjected to ac impedance analysis and changes in the ionic conductivity as a function of the type of filler added was analyzed at ambient temperature. These electrolytes demonstrated superior electrochemical properties with an exceptional electrochemical window exceeding ~ 4 V versus Zn/Zn2+, good voltammetric reversibility and zinc ion transference number averaging above ~ 0.63. Thermal stability of the samples was examined using thermogravimetry (TG) analysis whereas the variations in the surface morphology of the preferred samples owing to the incorporation of two distinct nanofillers were analyzed using scanning electron microscopy (SEM) study.

Iodine-free nanocomposite gel electrolytes for quasi-solid-state dye-sensitized solar cells

Iodine-free quasi-solid-state electrolytes were developed for dye-sensitized solar cells (DSSCs) by removing I2 from the conventional I−/I3− redox electrolyte and gelling the electrolyte with metal oxide nanoparticles. The inorganic nanoparticles played a dual role of gelling agent and charge transport enhancer. The removal of I2 improved the long-term stability of DSSCs, but reduced the ionic diffusivity of electrolyte and thus the solar-to-electricity efficiency of DSSCs. By introducing a suitable nanoparticle gelator into the electrolyte, the ionic diffusivity and the interfacial charge transfer could be enhanced due to the formation of 3-D networks that facilitate Grotthuss-type ion exchange. Three different metal oxide nanoparticles (SiO2, TiO2, and ZnO) were evaluated, and the best performance was obtained by TiO2 nanoparticles. The I2-free quasi-solid-state DSSCs gelled by 15% TiO2 achieved an efficiency of 8.00% vs. a 6.94% efficiency attained by the I2-free liquid-state reference cells. The I2-free quasi-solid-state DSSCs gelled by 15% TiO2 also exhibited good long-term at-rest stability with an estimated life span of five to six years under ambient condition based on an accelerated stability test performed at 65°C with 65% relative humidity.

Effect of doping nanoparticles on the output force performance of chitosan-based nanocomposite gel actuator

ABSTRACTIn this work, a kind of bio-inspired chitosan-based Nanocomposite Gel Actuator (NGA) was developed whose electrolyte membrane was fabricated by doping multi-walled carbon nanotubes (MCNT). Furthermore, the output force performance of NGA was studied. The results illustrated that doping MCNT particles will play a crosslinking role. The electrolyte membrane with different MCNT doping ratios could significantly reduce its elastic modulus and enhanced its specific capacitance. When the MCNT doping ratio was 2 wt%, the output performance of the electric actuator was the best and the output force density (19.17 mN/g) and strain (0.83 %) were increased by 92% and 17%, respectively.

High performance electrospun Li+-functionalized sulfonated poly(ether ether ketone)/PVA based nanocomposite gel polymer electrolyte for solid-state electric double layer capacitors

The synthesis of a nanocomposite gel polymer electrolytes (NGPEs) using Li+-functionalized SPEEK (SPEEK(Li)) nanofiber membrane as a matrix, cross-linked PVA as a gelled agent and LiClO4 as an electrolytic salt for electric double layer capacitors (EDLCs) were reported in this work. Compared with conventional PVA based gel electrolyte, the “SO3−Li+” functional groups and the pores structure of the SPEEK(Li) nanofiber membrane improves the ionic conductivity as well as mechanical stability, which made the prepared NGPEs exhibited a high ionic conductivity of 8.9 × 10−3 S cm−1 at ambient temperature and a large voltage stability window range from 0 to 2.0 V. The fabricated symmetric EDLCs showed a specific capacitance of 146.96 F g−1 at a current density of 0.5 A g−1, with a maximum energy density of 18.26 W h kg−1. Meanwhile, the EDLCs showed outstanding cyclical stability of 98% specific capacitance retention after 3000 cycles GCD testing, all of these results indicated that the NGPEs should be appropriate to EDLCs and next-generation energy storage systems.

Two-dimensional scattering patterns and stress-strain relation of elongated clay nano composite gels: Molecular dynamics simulation analysis

To verify the structure-properties relation of elongated clay nanocomposite (NC) gels through two-dimensional scattering patterns (2DSPs), we performed coarse-grained molecular dynamics (CGMD) simulations of a bead-spring model of NC gels. In order to reproduce the 2DSP behavior, we modeled a clay particle as a disk-like aggregation of a large number of beads. In our model of polymer networks filled with the clays, we maintained the structural relations of the clays such as shape, size, and concentration, and emulated gelation processes through CGMD simulations. As results, the model with a scale map with 1 σ = 2 nm, where σ is the scale unit of CGMD simulations, succeeded in reproducing behaviors of stress-strain relations and 2DSPs. After our pseudo reaction processes with bonding between the ends of the polymers and between polymer ends and clays, uniaxial stretching CGMD simulations were performed. It is found that rapid increases in the estimated stress-strain relation for large stretching ratio were caused by the percolated network of the NC gel model with high NC concentration. We confirmed that the dependences of clay concentration and stretching ratio on 2DSP and stress were consistent with the small-angle neutron scattering experiments and tensile experiments, respectively.

Pectin-graft-poly(2-acrylamido-2-methyl-1-propane sulfonic acid) silver nanocomposite hydrogel beads: evaluation as matrix material for sustained release formulations of ketoprofen and antibacterial assay

Pectin-graft-poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (Pec-g-PAMPS) gel was made in the form of beads by subjecting the solution containing pectin (Pec), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and ammonium peroxodisulphate to microwave irradiation followed by ionic crosslinking in CaCl2 solution. Gel beads containing silver nanoparticles were also prepared by the same method but with the addition of silver nitrate and trisodium citrate solution prior to microwave irradiation. The synthesized Pec-g-PAMPS and its silver nanocomposite (Pec-g-PAMPS-Ag) gel beads were characterized using FTIR, TGA, XRD, SEM, EDS and TEM techniques. The effect of incorporation of Ag NPs on the biological activity of Pec-g-PAMPS was studied by zone inhibition method considering two bacterial strains namely E. coli and B. subtilis. The nanocomposite gel exhibited higher antibacterial activity compared to the parent gel, which was comparable with the standard drug, Streptomycin. The in vitro drug release profiles of the parent gel and its composite were analyzed using Ketoprofen (KF) to study the effect of incorporation of Ag NPs on the drug release behavior of the Pec-g-PAMPS. The presence of silver nanoparticles enhanced both swelling of the gel beads and the extent of drug release significantly.