Preparation of cationic polyacrylamide by aqueous two-phase polymerization

One-Step Preparation of Antifouling Polysulfone Ultrafiltration Membranes via Modification by a Cationic Polyelectrolyte Based on Polyacrylamide

A novel method for one-step preparation of antifouling ultrafiltration membranes via a non-solvent induced phase separation (NIPS) technique is proposed. It involves using aqueous 0.05-0.3 wt.% solutions of cationic polyelectrolyte based on a copolymer of acrylamide and 2-acryloxyethyltrimethylammonium chloride (Praestol 859) as a coagulant in NIPS. A systematic study of the effect of the cationic polyelectrolyte addition to the coagulant on the structure, performance and antifouling stability of polysulfone membranes was carried out. The methods for membrane characterization involved scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), contact angle and zeta-potential measurements and evaluation of the permeability, rejection and antifouling performance in human serum albumin solution and surface water ultrafiltration. It was revealed that in the presence of cationic polyelectrolyte in the coagulation bath, its concentration has a major influence on the rate of "solvent-non-solvent" exchange and thus also on the rate of phase separation which significantly affects membrane structure. The immobilization of cationic polyelectrolyte macromolecules into the selective layer was confirmed by FTIR spectroscopy. It was revealed that polyelectrolyte macromolecules predominately immobilize on the surface of the selective layer and not on the bottom layer. Membrane modification was found to improve the hydrophilicity of the selective layer, to increase surface roughness and to change zeta-potential which yields the substantial improvement of membrane antifouling stability toward natural organic matter and human serum albumin.

Poly(ethylene glycol)-co-methacrylamide-co-acrylic acid based nanogels for delivery of doxorubicin

Polymeric nanogels have been widely explored for their potential application as delivery carriers for cancer therapeutics. The ability of nanogels to encapsulate therapeutics by simple diffusion mechanism and the ease of their fabrication to impart target specificity in addition to their ability to get internalized into target cells make them good candidates for drug delivery. The present study aims to investigate the applicability of poly(ethylene glycol)-co-methacrylamide-co-acrylic acid (PMA)-based nanogels as a viable option for the delivery of doxorubicin (DOX). The nanogels were synthesized by free radical polymerization in an inverse mini-emulsion and characterized by nuclear magnetic resonance spectroscopy ((1)H NMR), Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction and differential scanning calorimetry. DOX was physically incorporated into the nanogels (PMA-DOX) and the mechanism of its in vitro release was studied. TEM experiment revealed spherical morphology of nanogels and the hydrodynamic diameter of the neat nanogels was in the range of 160 ± 46.95 nm. The size of the nanogels increased from 235.1 ± 28.46 to 403.7 ± 89.89 nm with the increase in drug loading capacity from 4.68 ± 0.03 to 13.71 ± 0.01%. The sustained release of DOX was observed upto 80 h and the release rate decreased with increased loading capacity following anomalous release mechanism as indicated by the value of diffusion exponent (n = 0.64-0.75) obtained from Korsmeyer-Peppas equation. Further, cytotoxicity evaluation of PMA-DOX nanogels on HeLa cells resulted in relatively higher efficacy (IC50~5.88 μg/mL) as compared to free DOX (IC50~7.24 μg/mL) thus demonstrating that the preparation is potentially a promising drug delivery carrier.

Role of salt in the aqueous two-phase copolymerization of acrylamide and cationic monomers: from screening to anion-bridging

Mechanism for the anions effect on the aqueous two-phase copolymerization (ATPP) of acrylamide and cationic monomers in poly(ethylene glycol) (PEG) aqueous solution was proposed.

A survey on cationic polyelectrolytes and their applications: acrylamide derivatives

Cationic polyelectrolytes are water-soluble polymers bearing positive ionic groups along the backbone or in side chains. These cationic polymers are synthesized by free radical polymerization of acrylamide and their derivatives by the copolymerization method, which includes solution, precipitation, and emulsion techniques. The Mannich reaction is another important method by which the cationic polymers can be processed. In this review paper, the preparation methods, interaction mechanisms of these polymers, and their popular industrial applications are summarized. These polymers open a lot of applications in different fields such as paper-making processes, water and wastewater treatment, oil and drilling industries, mineral separation, paint and food industries, cosmetics, and pharmacy. In addition, these polymers are widely used as flocculants and rheology control agents. These polymers are especially employed in oil field operations as viscosity control agents for enhanced oil recovery, drilling fluid additives, and also for modifying flow and stability properties of aqueous solutions and gels. They are used as super-plasticizers, which affect the rheological properties of dense cement suspensions. Mining processes also benefit from the use of acrylamide derivative polymers to flocculate solids in aqueous dispersions. The cationic polymers may interact with different components in the system such as inorganic/organic particles in aqueous dispersions in several ways, which may result in the stability or instability of dispersion. The particles can be destabilized through three different main mechanisms which promote flocculation: polymer bridging, charge neutralization, and polymer adsorption.

A novel and controllable route for preparing high solid-content and low-viscosity poly(acrylamide-co-acrylic acid) aqueous latex dispersions

High solid-content and low-viscosity poly(acrylamide-co-acrylic acid) aqueous latex dispersions were obtained through a novel strategy, which involves swelling followed by diffusion and redox initialized polymerization inside the seed particle.

Unique multiple soluble-insoluble phase transitions in aqueous two-phase copolymerization of acrylamide and a weakly charged comonomer

A unique phenomenon of multiple soluble-insoluble phase transitions was found in the two-phase copolymerization of acrylamide (AM) and a weakly charged comonomer, N,N-dimethylaminoethyl methacrylate (DMAEMA), in the aqueous solution of poly(ethylene glycol) (PEG). As the DMAEMA molar fraction increased from 0 to 0.30, the insoluble-soluble (I-S) phase transition first appeared and then disappeared. Varying the PEG concentration, the salt concentration, or the pH of reaction mixture, the phase transitions were tuned dependently. The volume fractions and refractive indices of continuous and disperse phases, as well as the viscosity change in the phase transitions were investigated, and the results showed that phase reentrance had occurred in the I-S phase transition. The transitional conversion for the first S-I phase transition increased with the DMAEMA molar fraction, indicating the solubility enhancement of charged polyelectrolytes. The content of DMAEMA in the resulting copolymer first increased and then decreased as the polymerization progressed. Accordingly, the droplet size increased in the two S-I phase transitions and decreased in the I-S phase transition. And it was proved that the copolymers were molecularly solubilized after the I-S phase transition. The multiple soluble-insoluble phase transitions were ascribed to the synergistic effect of polymer concentration, solubility enhancement of charged copolymers, and the salting-out effect of ionic comonomers. A generalized mechanism for the multiple soluble-insoluble phase transitions was proposed, which showed that the effects of polymer concentration were dominant in the two S-I phase transitions, while the effects of solubility enhancement played a key role in the I-S phase transition.