Objective(s): Physiological changes in the body may be utilized as potential triggers for controlled drug delivery. Based on these mechanisms, stimulus-responsive drug delivery has been developed.Materials and Methods: In this study, a kind of poly (N-isopropyl acrylamide-acrylamide) membrane was prepared by radical copolymerization. Changes in swelling ratios and diameters of the membrane were investigated in terms of temperature. On-off regulation of drug permeation through the membrane was then studied at temperatures below and above the phase transition temperature of the membrane. Two drugs, vitamin B12 and acetaminophen were chosen as models of high and low molecular weights here, respectively.Results: It was indicated that at temperatures below the phase transition temperature of the membrane, copolymer was in a swollen state. Above the phase transition temperature, water was partially expelled from the functional groups of the copolymer. Permeation of high molecular weight drug models such as vitamin B12 was shown to be much more distinct at temperatures below the phase transition temperature when the copolymer was in a swollen state. At higher temperatures when the copolymer was shrunken, drug permeation through the membrane was substantially decreased. However for acetaminophen, such a big change in drug permeation around the phase transition temperature of the membrane was not observed.Conclusion: According to the pore mechanism of drug transport through hydrogels, permeability of solutes decreased with increasing molecular size. As a result, the relative permeability, around the phase transition temperature of the copolymer, was higher for solutes of high molecular weight.

In this study, a hydrogel composed of acrylamide (AAm) with N-vinylimidazole (NVI) as co-monomer, with a cross-linker such as N, N’ Methylenebisacrylamide and potassium peroxodisulfate as an initiator solution was prepared. Poly (AAm/NVI) hydrogels were synthesized by free radical solution polymerization. Swelling experiments were performed in water at 25oC, gravimetrically. Here, it was of interest to increase the water absorption capacity of AAm hydrogels with add VI. AAm is a highly hydrophilic monomer, and VI monomer is neutral. The one purpose of this study is to combine both monomers in one polymer. In this respect, a series of hydrogels was synthesized by changing the content of AAm and VI. Then, some swelling of these hydrogels was studied in water.

Poly(N-vinyl formamide-co-acrylamide) hydrogels were prepared by free radical chain polymerization using ammonium persulfate as redox initiator, N, N-Methylene bisacrylamide as crosslinker, and N, Nʹ, , Nʹ, ʹ, , Nʹ, ʹ, ʹ,-tetramethyl ethylenediamine as accelerator. The synthesis of hydrogels was confirmed by FTIR and SEM. The effect of compositional change and temperature on the mechanical and rheological behavior was explored in detail. Different rheological tests (flow curve, frequency sweep, creep recovery, and hysteresis loop) were conducted to study the effect of temperature (25–, 40 ℃, ), compositional change, and N-vinyl formamide concentration on the viscoelastic thixotropic behavior of copolymer hydrogels. Different rheological models (Bingham, modified Bingham, and Ostwald power law) were applied to check the pseudo plastic shear thinning non-Newtonian behavior, as confirmed by decline in viscosity with shear rate. Highly rough and microporous morphology, high thixotropy (hysteresis loop area of 4498. 5 Pa s−, 1 obtained from the hysteresis loop test), and better recovery percentage (95% form creep recovery) were observed for hydrogels having increased N-vinyl formamide (NVF) concentration. The obtained results showed an increase in mechanical strength with increasing NVF concentration in the hydrogels and their valuable applications for wastewater treatment, drugs delivery, cosmetics and so on.

Polyacrylamide is prepared by free radical polymerization mechanism in aqueous solution, using ammonium persulphate as initiator. Poly (acrylamide-co-sodium acrylate) or partially hydrolyzed polyacrylamide (PHPA) with different degrees of hydrolysis was obtained by alkaline hydrolysis of polyacrylamide using sodium hydroxide as hydrolyzing agent. The intrinsic viscosity of copolymers with different degrees of hydrolysis was measured with Ubbelohde capillary viscometer in 0.2 M sodium sulphate solution and related molecular weights (Mw) were estimated using Mark-Houwink equation. The results show that the intrinsic viscosity of copolymers increases with increasing the hydrolysis degree. We also found that sodium hydroxide as a hydrolyzing agent influences the Mw of parent polymer and causes significant reduction in product Mw while slight reduction has been reported. The degrees of hydrolysis of copolymers were determined based on a standard back titration method. In addition to titration method, IR spectra bands identified the carboxyl groups.

This investigation studies the antibacterial action of a novel palm resin – poly(acrylamide) based hydrogel silver nanocomposite. Palm resin-based semi-interpenetrating hydrogel networks (SIH) were synthesized through an improved free radical polymerization of acrylamide in the presence of palm resin using N,N-methylene bisacrylamide (MBA) as the cross-linker, ammonium persulphate (APS) as the initiator and N,N,N’,N’-tetramethyl ethylenediamine (TEMED) and heat as the activators for APS. In this one-pot preparation, SIH was formed in a short reaction time of 10 minutes. The formed SIH was converted into Hydrogel Silver Nanocomposite (HSN) by loading silver ions into the SIH matrix and reducing the silver ions to nanosilver with neem plant extract (Azadirachta Indica) as a green reducing agent. The formed HSN was probed with UV-Visible Diffused Reflectance Spectroscopy (UV-Vis DRS), Fourier Transform InfraRed (FT-IR) spectroscopy, High Resolution Scanning Electron Microscopy (HR-SEM), Energy Dispersive X-ray (EDX) analysis, X-Ray Diffraction (XRD) study, and thermogravimetric analysis (TGA). The effect of time, silver nitrate concentration, and pH on the swelling behavior of HSN and its antibacterial activity were investigated. The antibacterial studies revealed that the prepared HSN significantly decreases bacterial growth. The strong hindrance of Ago-loaded hydrogel against bacterial growth and the ideal release of nanosilver into the bacterial culture makes the HSN appropriate for biomedical applications.

Nowadays, use of polymeric mulch such as the polymer based on acrylamides is developing due to being eco-friendly, safety, and low cost. Polyacrylamide is odorless, colorless, non-polluting the ground water and surface water, soil and plant tissues. In this study, for the first time, copolymer based on acrylamide and acrylic acid was used in small-scale plots in experimental conditions for use in soil for the purpose of its stabilization and preventing its loss.Copolymer based on acrylamide and acrylic acid was synthesized by free radical polymerization.The water-soluble polymer synthesized by free radical polymerization and characterized using Fourier-transform infrared spectroscopy and thermogravimetric analysis. To calculate the negative charge density of samples, titration method was performed. By increasing density of negative charge of polymer chains, the apparent viscosity decreases with higher rate. It can be concluded that in the presence of acrylic acid, the ions shrank and became more like spheres which ultimately results in coil-like configuration. As the copolymerization reaction proceeds from 50% to 90% weight percent of acrylic acid, the rate slows down due to accumulation of negative charges and the molecular weight of copolymers decreases with increasing the anionic degrees of copolymers.Finally, soil loss was determined using 0.4, 0.6, 1, 2, 3, 4 and 6 gr/m2 of copolymers in water and solutions sprayed on the soil surface before implementation of artificial rainfall, also its continuity in 30min rainfall was studied.

In present work, poly(vinyl alcohol)-g-acrylamide was synthesized with two initiator systems, which contain ceric ammonium nitrate and ammonium persulfate/sodium metabisulfite redox systems. The structure of the graft copolymers was confirmed by Fourier Transform InfraRed (FT-IR) spectroscopy and ThermoGravimetric Analysis (TGA). The inhibition effects of produced graft copolymers (as new kinetic hydrate inhibitors) and polyvinyl alcohol were investigated on gas hydrate formation with a methane-propane mixture which forms the structure II of the hydrate. In all experiments, the initial pressure was adjusted at 23 bar, temperature at 2 ˚ C, and the stirring rate at 400 rpm. All of the tested materials reduce hydrate formation rate and their inhibition strength was PVA-g-AAM1