Sharif Digital Repository

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... 

In the past few decades, many attempts have been made to combine the benefits of homogeneous and heterogeneous catalysts. The immobilization of homogeneous catalysts onto the surface of heterogeneous supports is the result of such efforts. In this research, immobilized heterogeneous catalysts were designed and synthesized based on double network hydrogels, which produce from interpenetrating of two biocompatible and biodegradable polymer networks. In order to provide magnetic responsibility and easy separation of catalyst from the reaction mixture, the magnetic nanoparticles were dispersed onto the surface of double network hydrogel. Finally, various metal nanoparticles such as palladium and... 

Today, catalysts have shown the growing applications in chemical industries especially for drug synthesis. Using immobilized heterogeneous catalysts is a sensible way to benefit from advantages of both heterogeneous and homogeneous catalysts. In this regards, homogeneous catalysts are immobilized on to a solid support through various methods. However, low loading amount of homogenous part and subsequently insufficient catalytic activity are main limitations of immobilized heterogeneous catalysts. For this reason, polymeric supports have been introduced to immobilize metal ions or nanoparticles. These polymeric supports not only possess advantages such as anti-corrosive properties, simple... 

Hyderogels are hydrophilic polymers with three dimensional network structure, due to their high water absoption, their application to life and industry is increasing from day to day, such as tissue engineering, actuators and sensors, drug delivery and therapeutic treatment. In this project, it has been attempted to produce polyacrylamide/alginate double network hydrogels with the use of graphene oxide nanosheets to indicate that it is possible to combine toughness and self-healing in a hydrogel with the opposite nature of each other. To evaluate mechanical properties, uniaxial tensile test and loading-unloading test were used. The results indicate that increase the weight ratio of acrylamide... 

In recent years, burns and deep wounds that occur in various accidents are important reasons of death in the world. Therefore, the healing process of burn and full thickness of wounds due to late treatment has always been considered by physicians. Thus, the correct treatment and speed of healing of these types of wounds have always been studied. Many synthetic and natural materials have been used to treat wounds, which among them, hydrogels have received a great attention due to creating a moist environment for wounds and absorbing secretions. However, external mechanical stresses may degrade the therapeutic hydrogel. Recently, self-healing coating hydrogels have been designed and developed... 

Mammalian cardiac tissue lacks the ability to effectively self-regenerate following severe damage. The application of external therapeutic agents with strong mechanical properties is needed to restore its function. Even though conventional therapies have several challenges and limitations, injectable hydrogels, with minimally invasive, can significantly improve cardiac tissue regeneration. Extracellular matrices are the most appropriate biomaterials for synthesizing cardiac scaffolds. The human amniotic membrane obtained from the amniotic sac is a readily available, abundant, and inexpensive candidate that has been successfully utilized for the clinical treatment of cardiac diseases.... 

Osteoarthritis has always been one of the most common diseases in middle age because it causes severe pain and inflammation in the joints of the body. Cartilage tissue does not have the ability to repair itself. For this reason, fabricating and designing the most efficient, least-expensive, and most convenient methods for the treatment of cartilage defects is always an important issue. Today, there are surgical and injectable methods to relieve pain and initiate the body's natural healing response. But due to the many disadvantages and limitations of these methods, tissue engineering science has turned to modifying these methods or providing new methods. One of these methods is the use of...