جستجوی مقالات مرتبط با کلیدواژه « میکروژل » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Today, the presence of heavy metal ions in the wastewater of various industries is one of the environmental problems of the modern world. Therefore, various methods are used to adsorb and remove heavy metal ions from industrial wastewaters and effluents. One of the effective methods in this field is adsorption by polymer gels, which are divided into different categories including  hydrogels, aerogels, microgels and nanogels. These materials are porous cross-linked polymer networks. Having desirable physical and chemical properties such as high surface area, size variety, high durability, variety of solubility, active adsorption centers, and environmental compatibility, they can absorb heavy metal ions such as lead, cadmium, mercury and copper physically and chemically from contaminated aquatic environments without causing secondary destructive effects with high efficiency. The general structure of these gels is similar to each other, and factors such as pore size, mesh size, and the presence of liquid or gas in the pores create different categories. In this article, each types of gels and their unique properties are introduced first, then the general synthesis methods, special optimizations to enhance the adsorption and mechanisms of metal adsorption by gels are reviewed.

In recent years, there have been several studies on characterization and preparation of polymeric organogels and alcohol-absorbent organogels which are the subgroup of polymeric organogels. Considering the importance of sulfonic monomers to improve the absorption of alcoholic acrylic acid-based adsorbent gels, due to their ability to separate ionic groups in a low-dielectric solvent such as ethanol, and the use of carbopol in medical and pharmaceutical industries, in the present study, the alcohol-absorbent gels were prepared by grafting sulfonated monomer on the surface of carbopol particles.

Alcohol-absorbent gels were prepared by grafting sulfonated monomer through the ultrasonic method. The effect of monomer content on alcohol and saline solution absorbency was investigated through swelling measurement.

In samples with similar particle size, an increase in ionic monomer content increased the absorption of alcohol due to dissociation ability of sulfonic acid groups. For example, in a sample containing 75% ionic monomer, 13% increase in ethylene glycol adsorption and 27% increase in salt absorption were observed compared to that containing 25% ionic monomer. The polymer chains resulting from the grafting of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) on the carbopol particle surface helped to increase absorption under load because of retaining the consistency of the swollen samples. Glass transition temperature (Tg) of the prepared sample decreased by 48% compared to carbopol, because the side chains caused steric hindrance and negative charge on the grafted poly(AMPS) chains resulted in electrostatic repulsion. The study on the effect of physical parameters such as particle size on the alcohol absorbency showed that by increasing the particle size of the prepared samples, the absorption of alcohol dropped significantly because of reduction in the contact area of the particles with the solvent.

Microgels are micrometer-sized particles which consist of a cross-linked polymer network swollen by a solvent, typically water. Nowadays, these materials are an important topic of interdisciplinary research in the fields of polymer chemistry and physics, materials science, pharmacy, and medicine. They have a broad field of actual and potential applications ranging from filler materials in coating industry to modern biomaterials for controlled drug delivery. The most famous examples of microgel materials are cross-linked poly (acrylic acid) and its derivatives with various cross-linker types. One of the major applications of these materials is their use as thickeners. The high surface areas of microgels allow them to absorb large amounts of solvent to increase the viscosity of their solution. The purpose of this paper is to investigate methods for the synthesis of acrylic microgels, and to explain the advantages and disadvantages of each method depending on the application and at the end, a brief description will be made on their main applications.