Properties Of Nanocomposite Hydrogels Research Articles

Influence of TiO2 nanofiller geometry on the rheological and optical properties of poly(acrylic acid)‐based nanocomposite hydrogels

AbstractThe properties of macroscopic polymer nanocomposites are highly dependent on the nanoparticle–polymer interfacial region, which varies with the morphology of the nanoparticles. Herein, we used TiO2 nanofillers with very low aspect ratio, the same chemical composition, and surface functions, but different geometries (nanospheres and nanoplates) dispersed in a poly(acrylic acid) matrix to analyze the influence of the nanoparticle geometry on the properties of nanocomposite hydrogels. The geometry was found to affect the swelling and rheological properties of the nanocomposite polymers. Particularly, the yield strain (from 25% to 130%), modulus (from 17,500 to 25,000 Pa), and brittleness of nanoplates based nanocomposite increased more significantly. Finite‐difference time‐domain simulations demonstrated that nanoplates increased the wavelength of the absorption maxima (224 nm for NS to 240 nm for NP) and charge distribution. The results obtained in this research indicate that the nanofiller shape markedly influences the rheological properties of the nanocomposite polymers, opening the door to further research focused on polymer–nanofiller interactions, and their effect on the macroscopic properties of the nanocomposites.

Reinforcement Effects of Inorganic Nanoparticles for PAM‐g‐carboxymethyl Xylan Nanocomposite Hydrogels

AbstractA variety of 0D nanoparticles (MgO, ZnO, Al2O3, Fe2O3, SiO2, and TiO2) as nanofiller materials are introduced into polyacrylamide‐g‐carboxymethyl xylan (PAM‐g‐CMX) composite hydrogel. The effects of different shapes and different sizes of nanoparticles on the properties of hydrogels are investigated. The properties of nanocomposite hydrogels are analyzed by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy (SEM), rheological analysis, swelling analysis, and mechanical test. Composite hydrogels with nanoparticles exhibit uniform pore structure and smaller pore size in SEM images, resulting in a reduced equilibrium swelling ratio. In addition, the results show that the hydroxyl groups on the surface of the nanoparticles forms hydrogen bonds with the amino groups and carboxyl groups in the PAM‐g‐CMX cross‐linked network which improve the mechanical strength of nanocomposite hydrogels. The hydrogel with 20 nm MgO has the maximum compressive strength (550.9 kPa), tensile strength (28.6 kPa), and the longest elongation (813%) owing to the spherical shape and small size of MnO (20 nm). The hydrogels with nanoparticles maintain the originated 90% strength after 30 cycles of compressive test. The hydrogels with nanoparticles will offer new insights for xylan application.

Fabrication of bentonite reinforced dopamine grafted carboxymethyl xylan cross-linked with polyacrylamide hydrogels with adhesion properties

Two-dimensional bentonite nanomaterials were used as nanofiller materials to synthesize dopamine grafted carboxymethyl xylan cross-linked with polyacrylamide nanocomposite hydrogels. The properties of nanocomposite hydrogels were analyzed by FTIR, XRD, SEM, rheological analysis, swelling analysis and mechanical test. The results showed that bentonite as a nanofiller could promote the mechanical strength of nanocomposite hydrogels, in which the maximum compressive strength, maximum tensile strength and elongation at break of composite hydrogel were 42.17 kPa, 218.29 kPa and 436%, respectively. In addition, the catechol of dopamine imparted nanocomposite hydrogels with adhesion properties, and the composite hydrogels could adhere to glass, plastic, metal and PTFE.

Nanoparticle-Polymer Synergies in Nanocomposite Hydrogels: From Design to Application.

Hydrogels are an important class of soft materials with high water retention that exhibit intelligent and elastic properties and have promising applications in the fields of biomaterials, soft machines, and artificial tissue. However, the low mechanical strength and limited functions of traditional chemically cross-linked hydrogels restrict their further applications. Natural materials that consist of stiff and soft components exhibit high mechanical strength and functionality. Among artificial soft materials, nanocomposite hydrogels are analogous to these natural materials because of the synergistic effects of nanoparticle (NP) polymers in hydrogels construction. In this article, the structural design and properties of nanocomposite hydrogels are summarized. Furthermore, along with the development of nanocomposite hydrogel-based devices, the shaping and potential applications of hydrogel devices in recent years are highlighted. The influence of the interactions between NPs and polymers on the dispersion as well as the structural stability of nanocomposite hydrogels is discussed, and the novel stimuli-responsive properties induced by the synergies between functional NPs and polymeric networks are reviewed. Finally, recent progress in the preparation and applications of nanocomposite hydrogels is highlighted. Interest in this field is growing, and the future and prospects of nanocomposite hydrogels are also reviewed.

Hydrogel with high laponite content as nanoclay: swelling and cationic dye adsorption properties

Superadsorbent poly (acrylamide-co-itaconic acid)/nanoclay hydrogels were prepared by in situ free-radical polymerization of acrylamide and itaconic acid in an aqueous media with nanoclay as a crosslinker. The properties of nanocomposite hydrogels (NCHs) were characterized by FTIR spectroscopy, XRD patterns, and TGA thermal methods. Morphology of the samples was also examined by scanning electron microscopy. The swelling properties and cationic dye adsorption behaviors of the NCHs were also investigated. The adsorption behavior of the cationic dyes such as methylene green (MG), methylene blue (MB), and crystal violet (CV) were studied on the NCHs. The effects of the clay content of the hydrogel on its cationic dye uptake behavior were studied. The adsorption studies indicated that the rates of dye uptake by the NCHs increased in the following order: MG > MB > CV. The effect of time on the different dye adsorption by the NCH was nearly the same. The NCHs may be considered as a good candidate for environmental applications to retain more water and to remove dyes.

Preparation and Properties of Nanocomposite Hydrogel by Photoinitiated Polymerization

A novel hybrid hydrogel (SAT gel) based on covalent crosslinking was prepared by photoinitiated polymerization. Photoactive polystyrene (PS) nanoparticles were successfully synthesized by grafting photoinitiator 2-[p-(2-hydroxy-2-methylpropiophenone)] ethylene glycol methacrylate (HMEM) onto the surface of PS nanoparticles, and characterized by nuclear magnetic resonance (NMR), fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscope (HRTEM) and dynamic light scattering (DLS). In the presence of monomer (AAm), PS nanoparticles acting as multifunctional cross-linking agents, and in-situ polymerization was carried out on the surface of photoactive particles. This study focused on the effect of photoactive PS nanoparticles concentration and illumination time on the morphology and swelling behavior of SAT hydrogels. It revealed that the three-dimensional structure and swelling ratio decreased with the increasing concentration of PS nanoparticles. Moreover, the pore size compressed with extending the illumination time. Embedding photoactive nanoparticles into hydrogels network to prepare novel hydrogels had advantages of controllable polymerization process and short forming time. This method provided a new way to prepare soft materials and to design the intelligent hydrogels.

Poly(sodium 4-styrene sulfonate) and poly(2-acrylamidoglycolic acid) nanocomposite hydrogels: montmorillonite effect on water absorption, thermal, and rheological properties

A systematic study of water absorbency, thermal, and rheological properties was performed on nanocomposite hydrogels of poly(sodium 4-styrene sulfonate) (PSSNa) and poly(2-acrylamide glycolic acid) (PAAG). Montmorillonite was used as clay filler and was previously modified to hydrogel synthesis by addition of (3-acrylamide propyl)trimethylammonium chloride. Syntheses were carried out by in situ radical polymerization, using N,N-methylen-bis-acrylamide as crosslinker reagent. Nanocomposites showed an exfoliated morphology, confirmed by transmission electron microscopy and X-ray diffraction. The water absorption capacity (WAC) of unloaded PSSNa hydrogel was three times higher than for PAAG; due to clay addition, absorption capacity increased for PSSNa nanocomposites and decreased for PAAG. Finally, rheological properties of nanocomposite hydrogels were studied by both dynamic oscillatory test and shear creep analysis. Results showed improvements on mechanical properties, such as yield point, elastic recovery, and storage modulus as consequence of montmorillonite addition.

Effect of silver nanoparticles content on the various properties of nanocomposite hydrogels by in situ polymerization

A series of nanocomposite hydrogels (APEAg series gels) were prepared from acrylic acid, poly(ethylene glycol) methyl ether acrylate, and silver nanoparticles through in situ polymerization by UV irradiation. The effect of the content of silver nanoparticle on the properties of the nanocomposite hydrogels was investigated. Results showed that, with increasing of the content of the silver nanoparticle in the hydrogels, the crosslinking density and shear modulus of the hydrogel were not obviously changed, the electrical conductivities of the nanocomposite hydrogels increased, and their initial rate of Escherichia coli inactivation significantly increased, but their adhesive force only slightly decreased. These materials can be assessed as promising bioadhesive patch or wound-dressing material or electrical massage patch.

Composition dependent changes in the swelling and mechanical properties of nanocomposite hydrogels

We are synthetized thermo- and pH-sensitive gels, which are then tested as skin extenders. Our aim is the development of copolymer and composite hydrogels that, when implanted under the human skin, swell osmotically and thereby induce skin growth. During the polimerization reaction we are produced copolymers with varyable composition, which are proceed from two acrylic compounds [N- isopropyl- acrylamide (NIPAAm), and acrylamide (AAm)]. The mechanical strength and the swelling stability of the gels are enhanced by the addition of fillers [Na- montmorillonite (Na- m.) and with alkyl- ammonium ion organophilized Na- montmorillonites [(C n - m.), n = 4, 12, 18]. With this method we are synthetized composite- hydrogels. The filler content of composites varies between 1 and 25 wt%. We observed that in the case of composites synthesized with the addition of fillers, relatively low filler contents (1–5 wt%) resulted in more extensive swelling and stronger gel structure. In the course of the experiments the monom...

Preparation and properties of nanocomposite hydrogels containing silver nanoparticles by ex situ polymerization

AbstractA series of composite hydrogels containing silver nanoparticle used for bioadhesives were prepared from acrylic acid, poly(ethylene glycol) methyl ether acrylate, and silver nanoparticles through ex situ polymerization. Silver nanoparticles with a narrow size distribution were prepared by the reduction of a silver nitrate solution with ascorbic acid. The influence of the content of the silver nanoparticles in the hydrogels on the equilibrium swelling ratio, mechanical properties, electrical conductivity, and inactivation of Escherichia coli (E. coli) was investigated in this study. The results showed that the swelling ratios of the composite gels were reduced by silver nanoparticles in the gels but were not reduced with an increase in the content of silver nanoparticles. In addition, the crosslinking density and shear modulus of these hydrogels did not increase with an increase in the content of silver nanoparticles. The adhesive force of these hydrogels (the APECAg series) was not obviously changed. Finally, the initial rate of E. coli inactivation for the APECAg series hydrogels showed excellent antibacterial properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3653–3661, 2006