Preparation Of Nanocomposite Hydrogels Research Articles

Synthesis of photoactive nanocomposite hydrogels via in-situ photoinitiated thiol-ene click polymerization of acrylates containing norbornene-POSS and norbornene-POSS/Ag NPs

Radical-mediated thiol-ene photopolymerization is a method that has been studied intensively since the beginning of the century due to the nature of click chemistry which can be carried out in a fast, controllable, and easy way under mild environment conditions with no or minimal formation of by-products. In order to improve the properties of the polymeric nanocomposite materials which have been obtained by photopolymerization method and to prepare them for a particular purpose, various nano-sized photo-reactive groups or cross-linking agents have been added to the formulations. The advantage of this study for the preparation of thin-film and hydrogel nanocomposites is based on one-pot thiol-ene photo-click polymerization. The main contribution made by one-component Type II photoinitiator, 2-Mercaptothioxanthone (TX-SH) carries both thiol functionality and chromophoric group on it. Polyhedral oligomeric silsesquioxane (POSS) functionalized with 1 or 3 norbornene units was used as alkene and played a good role in the preparation of nanocomposite hydrogels with/without in-situ formed silver nanoparticles (Ag NPs) with various acrylate content by thiol-ene photo-click polymerization. Especially the good contribution of norbornenylethyl disilanol isobutyl polyhedral oligomeric silsesquioxane (1NBPOSS) or tris-norbornenyl isobutyl polyhedral oligomeric silsesquioxane (3NBPOSS) was seen in terms of conversion percentage of acrylates which was determined by photo differential scanning calorimetry (photo-DSC) and swelling ratios of hydrogels in phosphate buffer solution (PBS) buffer solution. Besides them, obtained nanocomposites displayed good thermal stability values according to the Thermogravimetric analysis (TGA) measurements and scanning electron microscopy (SEM) images confirmed rather small-sized and uniform in-situ formed Ag NPs.

Preparation of Nanocomposite Hydrogel with High Mechanical Strength and Reusability for Cu(Ii) and Pb(Ii) Removal from Water

Preparation of Nanocomposite Hydrogel with High Mechanical Strength and Reusability for Cu(Ii) and Pb(Ii) Removal from Water

Preparation of nanocomposite hydrogels with nanoclay: characterization, swelling properties and dye adsorption behavior

Preparation of nanocomposite hydrogels with nanoclay: characterization, swelling properties and dye adsorption behavior

Self‐Assembled Injectable Nanocomposite Hydrogels Stabilized by Bisphosphonate‐Magnesium (Mg2+) Coordination Regulates the Differentiation of Encapsulated Stem Cells via Dual Crosslinking

Nanocomposite hydrogels consist of a polymer matrix embedded with nanoparticles (NPs), which provide the hydrogels with unique bioactivities and mechanical properties. Incorporation of NPs via in situ precipitation in the polymer matrix further enhances these desirable hydrogel properties. However, the noncytocompatible pH, osmolality, and lengthy duration typically required for such in situ precipitation strategies preclude cell encapsulation in the resultant hydrogels. Bisphosphonate (BP) exhibits a variety of specific bioactivities and excellent binding affinity to multivalent cations such as magnesium ions (Mg2+). Here, the preparation of nanocomposite hydrogels via self‐assembly driven by bisphosphonate‐Mg2+ coordination is described. Upon mixing solutions of polymer bearing BPs, BP monomer (Ac‐BP), and Mg2+, this effective and dynamic coordination leads to the rapid self‐assembly of Ac‐BP‐Mg NPs which function as multivalent crosslinkers stabilize the resultant hydrogel structure at physiological pH. The obtained nanocomposite hydrogels are self‐healing and exhibit improved mechanical properties compared to hydrogels prepared by blending prefabricated NPs. Importantly, the hydrogels in this study allow the encapsulation of cells and subsequent injection without compromising the viability of seeded cells. Furthermore, the acrylate groups on the surface of Ac‐BP‐Mg NPs enable facile temporal control over the stiffness and crosslinking density of hydrogels via UV‐induced secondary crosslinking, and it is found that the delayed introduction of this secondary crosslinking enhances cell spreading and osteogenesis.

Preparation and Characterization of Chitosan - Double Walled Carbon Nanotubes Hydrogels

In the present article, the authors have prepared nanocomposites based on chitosan (CS) and double walled carbon nanotubes (functionalized with carboxyl groups (DWCNT-COOH) and un treated DWCNT) by casting the stable mixture in a mold. Different concentrations of DWCNT were used in the preparation of nanocomposite hydrogels. These differently concentrated DWCNT hydrogels were chemically characterized using Fourier Transform-Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Thermal analysis and calorimetry (TGA). The dispersion of the carbon nanotubes were observed in the chitosan matrix by SEM. The addition of DWCNT in the composite hydrogel significantly reduced the water uptake ability. However, the water uptake ability of the CS/DWCNT-COOH nanocomposite has been better than the CS/ DWCNT. Also, dispersion of functionalized DWCNT in the chitosan matrix, was increased the thermal stability of hydrogels.

Preparation of amphoteric nanocomposite hydrogel under supercritical carbon dioxide and its fast-swelling behaviours

Supercritical carbon dioxide (scCO2) has been widely used in preparation of nanocomposite materials. However, so far there has been no report on preparation of nanocomposite hydrogels by intercalation of hydrophilic monomers into clay under scCO2 condition. In this paper, the fast-swelling amphoteric nanocomposite hydrogels were prepared via the free radical polymerisation of acrylic acid (AA) and N-[3-(dimethylamino) propyl] methacrylamide (DMAPMA) in the presence of clay under scCO2 condition. The composition of the hydrogel was determined by element analysis and Fourier transform infrared spectroscopy (FTIR). Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results illustrated that the clay layers became disordered after intercalation by AA and DMAPMA under scCO2 condition. The swelling kinetics and deswelling characteristics were tested. The results indicated that the hydrogels presented marked swelling rate in deionised or saline water and fast deswelling rate in alcoholic solution.

Preparation of Nanocomposite Hydrogel and Its Adsorption of Heavy Metal Ions

An acylamino and hydroxyl functionalized hydrogel [p(HMAm/HEA)] was newly prepared by the 60 Co-γ-induced polymerization of N-hydroxymethyl acrylamide (HMAm) and 2-hydroxyethyl acrylate (HEA). Then the copolymer p(HMAm/HEA) hydrogel was utilized for in situ nanosized hydrous manganese dioxide (HMO) loading to prepare nanocomposite hydrogel HMO-p(HMAm/HEA) for Pb2+ and Cu2+ removal. The nanocomposite hydrogel was characterized by SEM, TEM and FTIR, showing that p(HMAm/HEA) hydrogel was indeed a copolymer of HMAm and HEA monomers, and the loading of HMO nanoparticles onto p(HMAm/HEA) was successful. Various influencing parameters on heavy metal ions removal by HMO-p(HMAm/HEA), such as initial pH, temperature, initial heavy metal concentration, contact time and competing Ca2+ and Na+, were estimated. The results showed that the adsorption process was temperature-independent, pH-sensitive, Langmuir monolayer adsorption and followed a pseudo-second-order rate equation. The presence of high concentrations of competing Ca2+ and Na+ had no significant effect on the adsorption process. The XPS spectra analyses further indicated that Pb2+ and Cu2+ were adsorbed via the ion exchange of -OH groups. Moreover, HMO-p(HMAm/HEA) could be regenerated by 0.05 mol·L-1 of HCl, and obtained excellent repeated use.

Preparation of Nanocomposite Hydrogels and Its in vitro Release Behaviour on Captopril

Preparation of Nanocomposite Hydrogels and Its in vitro Release Behaviour on Captopril

Study on a novel polyampholyte nanocomposite superabsorbent hydrogels: Synthesis, characterization and investigation of removal of indigo carmine from aqueous solution

The aim of this study was to synthesize and characterize the novel polyampholyte nanocomposite hydrogels (NH) and to investigate the efficiency in the removal of the indigo carmine from the aqueous solutions. Acrylic acid (AA), 2-(diethylamino)ethyl methacrylate (2-DEAEMA) and montmorillonite (MMT) were used as ionic monomers and inorganic component, respectively. In the preparation of NH, in-situ free radical addition polymerization technique was used in the aqueous media. The formation of NH was confirmed by FTIR and XRD analyses. All NH are sensitive to pH and they have zwitter ion characteristics at pH 7.21. The diffusion of water into these gel systems is assumed to be a non-Fickian behavior. The indigo carmine adsorption rate of NH is faster than that of hydrogel. The kinetic studies for indigo carmine adsorption onto NH show that the pseudo-first-order adsorption mechanism is predominant. The adsorption isotherm data indicate that the BET model is the best fit model. It was concluded that the NH synthesized in this study being an adsorbent with the best mechanical properties might be suitable alternative for the removal of indigo carmine from textile aqueous effluents.