Sharif Digital Repository

This thesis focouses on the preparation and super-swelling behavior of two superabsorbent hydrogel. In the first section, a new superabsorbent hydrogel based on agar was prepared and the effect of the ratio of some components(AA, AAM, MBA, APS and agar) on the swelling capasity of the hydrogel was studied. Maximum water absorbency of the optimized final product was found to be 614.5 g/g in distilled water. The structure of the hydrogel was characterized by FT-IR method and morphology of the samples was examined by scanning electron microscopy(SEM). Swelling behavior properties of optimized hydrogel sample in different swelling medium were investigated. In the second section, we report the... 

This thesis focuses on the preparation and super-swelling behavior of a superabsorbent hydrogel based on natural macro-molecules and loading potassium nitrite as an agro-chemical onto it. 1-In this investigation a new type of superabsorbent hydrogel based on Gelatin and k-Carrageenan was prepared and the effect of the feed ratio of some components (acrylic acid, MBA, APS, and agar) on the swelling capacity of the hydrogel was systematically studied. The structure of the hydrogel optimized final product was found to be 1064 g/g in distilled water. The structure of the hydrogel was characterized by FT_IR method and morphology of the samples was examined by scamming electron microscopy (SEM).... 

Plasticizers in cementitious systems are additives that upon addition at a low dosage can change the workability, mechanical strength and other properties of cement paste effectively. In this study, tri-block copolymers based on poly ethylene glycol (PEG) was synthesised and their applications in the cementitious systems investigated. The main purpose is the verification of plasticizing effects of these copolymers in the cement paste. ABA tri-block copolymers with PEG (1000 and 1500 g/mol) as B block, poly caprolactone, poly caprolactam, poly lactide and poly glycolide (with different weight ratio) as A block were synthesised via ring opening polymerization with stannous octanoate as... 

Some chemotherapy drugs have unpleasant side effects and use them due to the instability and low solubility in blood flow is associated with problems and limitations.To solve these problems, controlled drug delivery systems have been proposed. In this process, the polymer increased solubility, stability and low toxicity and the active drug realease in a particular tissue or controlled speed. Therefore be less adverse side effects. Dextran is the one of biocompatible and water-soluble polysaccharides that due to its unique characteristics, widely used as carriers in drug delivery. Dextran molecules can bind to drugs and increased solubility, stability, and reduce their side effects.... 

Superabsorbent polymers are mainly used in baby diapers and in agriculture. A less known emerging and potentially important application is the internal curing of cement based materials. About a decade ago, pioneering works demonstrated that using SAP in concrete reduces autogenous shrinkage and cracking, and improves hydration of the cement matrix. However, problems like workability reduction, and deterioration of mechanical strength of the mixture are reported. In this thesis, nanocomposites using nanosilica and acrylic monomers were prepared and used to address the above problems. Nanocomposites exhibit enhanced mechanical strength and reduced sliding friction, compared with conventional... 

In this work, pH sensitive supramolecular shuttles consisting of carbon nanotube-graft-pyrene (CNT-graft-PYR) and hyperbranched polyglycerol with β-cyclodextrin core (β-CD-graft-PG) were synthesized and characterized. Supramolecular systems (PG/CNT/S) were able to load and transport doxorubicin in aqueous solutions. While PG/CNT/S were soluble in phosphate buffer pH 7, they were divided to their individual moieties in pH 5 and therefore CNTs containing staked doxorubicin molecules were precipitated  

The nanoparticles have been widely used in the field of physics, chemistry, electronics and mechanics because of their high surface area. One of their most important applications is in drug delivery systems as smart drug nanocarrier. Magnetic nanoparticles (including Fe2O3, Fe3O4) are the good candidates for this purpose. It is clear that, upon to entrance of nanoparticle into biological media (such as plasma), the surface of nanoparticles were covered by protein layers (protein corona). This layer is very stable and created new surface on the nanoparticles. The protein corona layer intracts with cellular receptors and determines the fate of nanoparticles. Protein corona covers the targeting... 

In recent years, cancer is the second leading cause of human death. Cancer treatment is based on surgery, chemotherapy and radiation therapy. Choice of treatment method depends on the degree of progression and type of cancer. However, the goal is destruction of cancer cells and minimal harmful side effects on healthy cells. In this thesis two types of polysaccharide-anticancer drug conjugate were prepared and evaluated for radiation therapy and chemotherapy; chitosan- and DTPA modified chitosan – Gallium 66 conjugates for radiation therapy and nano diacid starch –cisplatin conjugate for chemotherapy. Chitosan –gallium 66 conjugate was prepared in radiochemical purity higher than 99% at... 

Graphene، a molecular single layer of graphite، has tremendous applications in materials science for the development of nanocomposites، tissue engineering and supercapacitors. Graphene application and its developing applications depend on its essential properties such as excellent mechanical and thermal properties. Accordingly، investigation on graphene has drawn significant attention to itself. Hence، exploitation of these important properties including the induction of graphene sheets in polymer matrix seems to be essential. In the present survey، salep، a biodegradable polysaccharide، has been used for either the reduction of graphene oxide or functionalization of graphene. Then، reduced... 

Double network (DN) hydrogels are a new interpenetrate polymer network (IPN) that are usually contain about 60-90 % water. Despite of this amount of water, they are though and strong. DN hydrogels comprise of two networks, the first one as the brittle gel, is generally high density crosslinked and the second one, the loose and stretchable network, is loosely crosslinked or even without crosslinking. Therefore, we used cationic polymer, chitosan, and anionic polymer, alginate, as the first networks, therefore, we used sodium phosphate for physical crosslinking of chitosan, and calcium chloride as the physical crosslinking agents for alginate network. Also, poly (vinyl alcohol) (PVA), as the... 

Polysaccharide is important in terms of their environmental interest, scientists have been growing. According to the structural properties of this interesting class of natural polymers, in terms of having chemically active groups on the high density polymer housing provides the possibility That can perform chemical reactions with the new properties of these polymers to give. Starch polysaccharides in the project through a chemical reaction to the structure of a third type of bridge Amen to that using 1HNMR and 13CNMR predicted structure was approved. The modified polysaccharide has catalyst activity. This activity in knovenagel reaction for some aldhydes was used and results were... 

Hydrogels are crosslinked hydrophilic polymers that are capable of imbedding large amounts of water or biological fluids usually to equilibrium. Because of their unique properties, these materials have become ubiquitous and indispensable materials in many applications in recent years. Synthetic methods have produced numerous hydrogel materials with excellent properties. However, their nonbiodegradability might pose long-term environmental problems and limit their use. As a consequence, various research groups have put considerable amounts of effort and resources toward development of new absorbent materials from natural polymers such as polysaccharides. In this research, new hydrogel... 

Recently, biopolymers such as alginate, cellulose, chitosan, gelatine, starch and wool have been used as supports for catalytic applications. Several interesting features of the biopolymers for example, bio-degradable, environmentally safe, high sorption capacity, physical and chemical versatility make them attractive to use as supports. This study, the four functionalized biopolymer-based composites were designed and synthesized as well as heterogeneous catalysts used in the synthesis of 1,2,3-triazoles, oxidation of alcohol, reduction of nitroarenes and carbon-carbon coupling reactions.A novel cellulose supported copper NHC complex has been prepared by the reaction of cellulose supported... 

The use of super-swelling polymers is steadily increasing and the applications in industry are continuing to grow. With the authorization of the superabsorbents in food packaging by the Food and Drug Administration recently, demand may soon take off in the market. The worldwide production of SAPs is more than one million tons per year, representing a multibillion-dollar market. However, the increase in prices of petroleum products in recent years may be a drawback for these acrylic-based materials. Thus, there is now a need to develop natural-based super-swelling hydrogels which are more economical and environment friendly. In addition, the super-swelling gels are promising novel functions... 

This thesis focuses on the preparation and super-swelling behavior of four highly porous hydrogels: 1. Firstly, we have developed a collagen-based highly porous hydrogel by neutralizing the grafted poly(acrylamide-co-acrylic acid) after gel formation. Systematically, the certain variables of the graft copolymerization were optimized to achieve maximum swelling capacity. Morphology of the samples was examined by scanning electron microscopy (SEM) and was shown the pores were induced into the hydrogel by water evaporation resulting from neutralization process. The absorbency under load (AUL) and centrifuge retention capacity (CRC) were measured. The synthesized hydrogel exhibited a... 

Atom transfer radical polymerization (ATRP) is a convenient approach to synthesis of polymer with narrow molecular weight distribution. ATRP of acrylamide (AAm) is taken into consideration because of the intrinsic properties of acrylamide such as water solubility and biocompatibility. As reported in many recent works, polymerization of acrylamide by this method didn’t provide monomodal molecular weight distributions. In best condition with strong ligands such as Me4Cyclam, polymerization was carried out in a short time with high yield but polymerization was not highly controlled. It was shown that polymerization of acrylamide under typical ATRP condition displayed a much lower ATRP... 

With the fast progress of nanotechnology, targeted drug delivery systems have been widely developed due to decreasing in the drug dosage and subsequently side effects of them into body. These smart systems are able to response to the surroundings stimuli. External stimuli in comparison with internal stimuli are more controllable, and can release drug at the targeted side in the desirable times. In the recent studies, there has been an increasing interest in the usage of LASER as an external stimulus due to high precision, short time response, and suitable practical function. For cancer therapy, several studies have been done by focusing on the hyperthermia effects of gold nanoparticles. In... 

Today, current methods are used for treatment of cancers. Patient experiences a period of hard treatment during destruction of both healthy and diseased cells. Researchers are following stimulus- response drug delivery systems that they control time and position of drug release. Meanwhile, micellar nanoparticles are important, because it can transport the hydrophobic anticancer drugs from body's physiological barriers. On the other hand, tumour tissue has low pH and high temperature as compared to health tissue. Therefore, using pH and thermosensitive polymer coating could be effective in triggered drug release. In the first study, micellar systems were synthesized which were responsive to... 

In recent years, parallel to the development of industrial, the use of organic solvents and the environmental pollution caused by their increasing, more attention to remove these contaminants growing. Among the various absorbents to absorb pollutants from the environment, iron oxide nanoparticles have many applications in absorption and removal of environmental pollutions due to their high specific surface area, magnetic properties and ease of separation. The aim of this research is synthesis of a magnetic gel for absorption of organic solvents which in its structure magnetic nanoparticle and hydrophobic monomer is used. The most important advantages are the ease of isolation of the desired... 

Nowadays, because of the importance of saving energy resources and also environmental issues, utilization of catalysts are increased in industry and products. In the last decades, a lot of efforts have been devoted to develop novel methods for heterogenizing of the homogeneous catalyst in order to combine the advantages of the both the homogeneous and the heterogeneous catalysts. Among the different solid supports, graphene with high surface area and distinctive mechanical and electronical properties have been introduces as an emerging support for heterogenizing of the homogeneous catalysts. On the other hand, the use of ionic liquid has been developed due to a broad range of polarity, low...