Synthesis of copolymeric hydrogels of acrylamide and 2-(hydroxyethyl methacrylate) and its use for the adsorption of basic blue 3 dye

Homo and copolymer hydrogels of acrylamide and 2-hydroxyethyl methacrylate (HEMA) were synthesized by free radical addition polymerization. The synthesized hydrogels were characterized by scanning electron microscopy (SEM), thermal gravimetric and differential thermal analysis (TGA/DTA). The hydrogels were used as an adsorbent for the removal of toxic azo dye Basic blue 3 (BB3) in aqueous medium. To check the swelling property the equilibrium swelling of these synthesized hydrogels were established within 24 h. The effect of pH, time and temperature in the process of BB3 adsorption was studied in detail. The maximum adsorption of BB3 on hydrogels was occurred at pH 9 with 60 min equilibration time. The kinetic data were applied to pseudo first order, pseudo second order and intraparticle diffusion model. The obtained results indicate that the adsorption process, obey pseudo second order kinetics and is diffusion control. The negative value of ΔS and positive values of ΔG and ΔH showed that the adsorption process is orderliness, non-spontaneous and endothermic respectively in nature. The hydrogels were successfully regenerated from the mixture and used again in several steps without a reduction in their efficiency.

Synthesis and Rheological Survey of Xanthan Gum Based Terpolymeric Hydrogels

Graft copolymerization technique was used to synthesize novel biopolymer based terpolymeric hydrogels of xanthan gum (Gx), acrylic acid and N-Isopropyl acrylamide (NIPAM) by using chemical crosslinker N,N′-methylene bisacrylamide (MBA), ammonium persulphate (APS) as a redox initiator and sodium dodecyl sulphate (SDS) for particle size stabilization. The synthesized hydrogels were characterized through FT-IR and SEM techniques, which confirmed the hydrogels formation. Detailed rheology was investigated through applying various rheological models like Bingham model, modified Bingham model and Ostwald power law model to the hydrogels which revealed that the hydrogels were appeared to have shear thinning, non-Newtonian behavior and more elastic. Modified Bingham model provided best fit understanding to our prepared materials. The maximum activation energy (Ea) 13.87 kJ/mol was obtained for composition having more Gx compared to others, showing a strong relationship with viscosity. The hydrogels has potential to find applications in food industry, cosmetics, degradation of dyes and removal of heavy metals from waste water.

Rheological Investigation of GO Doped p(APTMACl) Composite Hydrogel

The aim of the present work is an approach towards the exploration of comprehension of rheological work on polymer composites synthesized by ex-situ dispersion of graphene oxide (GO) in poly(3-acrylamidopropyl trimethyl ammonium chloride (APTMACl) cationic hydrogel template. FTIR was carried out for confirmation of polymer synthesis and existence of GO in hydrogel network. The rheological investigation via frequency sweep curve (shear measurement) and oscillatory sweep (dynamic mechanical analysis) at different temperature 20, 25, 30, 35, 40 and 45 °C was performed. The storage (G′) and loss (G′′) moduli as a function of angular frequency, yield stress, tangent loss, damping factor and retention property were also studied to confirm the visco-elastomeric nature of the GO@p(APTMACl) composite and their semi solid response at different range of temperature. Various rheological models like Bingham model, modified Bingham model and Ostwald’s power law were applied. The temperature dependency was further tested via Arrhenius-Frenkel-Eyring equation. The sample showed best fitting in the modified Bingham model, which justified the pseudo plastic semi solid behavior of GO@p(APTMACl) composite within the linear visco-elastic region (LVER). All the properties from rheological study show best mechanical property and make the composite hydrogel good for drug delivery and for other environmental applications.

Preparation and Physicochemical Characterization of Dual Responsive and Chemically Modified Cellulose Based Copolymer Hydrogels

This research work is based on the preparation and physicochemical characterization of Poly(N-isopropylacrylamide)–Cellulose–Poly(Acrylic acid) [PNIPAAm–Cellulose–PAAc] based terpolymer hydrogels. The free radical polymerization reaction was initiated by the presence of ammonium persulphate (APS) and crosslinking between different monomers was occurring through N,Nl- Methylene bis-acrylamide (MBA). Confirmation of polymerization process was done by FT-IR and UV-visible spectroscopy. The prepared hydrogels were further characterized by different physicochemical techniques like rheology, Ostwald viscometry and dynamic light scattering (DLS). The effect of external stimuli like temperature, pH and composition of the samples on the physicochemical behavior was also carried out by dynamic rheology, swelling measurement and DLS. Various other properties like elasticity, shear stress, shear strain, loss modulus, storage modulus and complex viscosity was investigated by rheology. DLS was used to trace the size and swelling behavior of the samples. From the results obtained it was found that all the microgel samples are stimuli responsive and most of their physicochemical properties were prominently varying while changing the internal as well as the external experimental variable. These changes in physicochemical behavior of the gel can be attributed to two possibilities; the change in the hydrophobic character of gel (PNIPAAm) with temperature and also to the weakening of intermolecular hydrogen bonds with increase in temperature. As a result of this the PAA chains may undergo a transition from a compact conformation to an expanded coil conformation, resulting in the swelling of the hydrogels.

Thermal and Rheological Study of Nanocomposites, Reinforced with Bi-Phase Ceramic Nanoparticles

In this study the synthesis of bi-phase nanoparticles of Fe1.46Zn0.5La0.04Cu0.5O4 (FZLCs) ceramics were first carried out by Sol-gel method and then nanocomposites of FZLCs with polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG) and polyethylene oxide (PEO) were prepared by one-pot blending technique. XRD, FT-IR, TG/DTA and SEM techniques were applied for complete characterization of composites. Rheological and dielectric properties of all nanocomposites were studied in detail for their comparative performance. TGA results reveal the highly thermal stability for all nanocomposites in this order i.e. FLZCs/PEO > FLZCs/PVA > FZLCs/PVP > FZLCs/PEG. Rheological properties show that these materials are rigid, pseudo plastic and non-Newtonian in nature. The increase in values for storage modulus (G′) and loss modulus (G′′) with increasing angular frequency owed to the shear thinning behavior of these nanocomposites. Dielectric properties show good agreement to that of energy storage substances which means that these materials have potential to be applied in storage devices.

One-Pot Synthesis and Rheological Study of Cationic Poly (3-acrylamidopropyltrimethyl ammoniumchloride) P(APTMACl) Polymer Hydrogels

The main objective of this research work is to explore the complete and extensive rheological studies of cationic poly (3-acrylamidopropyl trimethyl ammonium chloride) P(APTMACl) hydrogel, prepared by free radical polymerization method at room temperature. Hydrogel was characterized by various techniques such as SEM, FTIR and TGA, whereas rheological properties of synthesized hydrogel were obtained using frequency sweep and frequency curve analysis in different temperature range. Storage modulus (G′) and loss modulus (G′′) were investigated as a function of angular frequencies and shear stress at various temperatures. Rheological models like Bingham plastic model, modified Bingham and Ostwald power law were applied to understand the rheological performance of the gels. Flow curves obtained at different temperatures indicate that P(APTMACl) hydrogel shows a non-Newtonian pseudo plastic behavior. All results concluded that rheology is a powerful tool to study the complete visco-elastic behavior of polymer hydrogel for multiple applications.

Uptake of heavy metal ions from aqueous media by hydrogels and their conversion to nanoparticles for generation of a catalyst system: two-fold application study

Poly(methacrylic acid) (P(MAA)), poly(acrylamide) (P(AAm)) and poly(3-acrylamidopropyltrimethyl ammonium chloride) (P(APTMACl)) were synthesized as anionic, neutral and cationic hydrogels, respectively. The synthesized hydrogels have the ability to be used as absorbents for the removal of selected heavy metal ions such as Cu²⁺, Co²⁺, Ni²⁺ and Zn²⁺ from aqueous media. Absorption studies revealed that the absorption of metal ions by the hydrogels followed the order Cu²⁺ > Ni²⁺ > Co²⁺ > Zn²⁺. For the mechanism of absorption, both Freundlich and Langmuir absorption isotherms were applied. Metal ion entrapped hydrogels were treated using an in situ chemical reduction method in order to convert the metal ions into metal nanoparticles for the synthesis of hybrid hydrogels. The synthesis and morphology were confirmed using FT-IR and SEM, while the absorbed metal amounts were measured using TGA and AAS. The hybrid hydrogels were further used as catalysts for the reduction of macro (methylene blue, methyl orange and congo red) and micro (4-nitrophenol and nitrobenzene) pollutants from the aqueous environment. The catalytic performance and re-usability of the hybrid hydrogels were successfully investigated.

Poly(methacrylic acid) (P(MAA)), poly(acrylamide) (P(AAm)) and poly(3-acrylamidopropyltrimethyl ammonium chloride) (P(APTMACl)) were synthesized as anionic, neutral and cationic hydrogels respectively.