فصلنامه بسپارش
سال یازدهم شماره 4 (پیاپی 41، زمستان 1400)

Blending of polymers is one of the useful methods for developing polymeric materials with improved properties or creating special properties in polymers. The mixture of some polymers is completely or partially miscible, but the mixture of many polymers is immiscible and their microsructure will be multiphase due to high molecular weight and undesirable interactions. Extensive research has been conducted on the development of  blend compatibilization approaches. Surface modifcation of polymers, addition of block copolymers, reactive compatibilization, crosslinking, interpenetrating networks, and more recently the addition of fllers in the micro and nano dimensions are some of the methods used to improve the compatibility of mixtures. The reduction of modulus and its related properties, when adding polymeric compatibilizers has caused researchers to pay more attention to nanoparticles and their compatibility effect. Compatibility mechanisms of polymer blends using nanoparticles can be divided into two modes based on their location in the blend. Firs, nanoparticles in the matrix phase, by forming a three-dimensional network and increasing the viscosity, apply more sress to the dispersed phase, reduce the size of the dispersed regions, and then reduce the coalescence phenomena of dispersed particles. In the second case, the nanoparticles, by locating at the interface between the matrix and dispersed phases reduce the interfacial sress and increase the interfacial adhesion. Also, in this case, they prevent the integration of scattered phase droplets. In this paper, the effect of nanoparticle compatibility on polymer blends, mechanisms, and the afecting sructural factors are reviewed

Reconsructive medicine is a growing feld for repairing damaged tissues in living organisms and is now proposed as a new treatment. For this purpose, polymeric biomaterials (scafolds) and living cells are used. The aim of this sudy was to invesigate the application of bioactive polylactic acid scafolds in the regeneration of various tissues.  Polylactic acid is a synthetic biopolymer that has been proposed in recent years as an important proposal in the production of tissue engineering scafolds. This polymer is a biocompatible, biodegradable and biosorbable material that is completely hydrolyzed in the living organisms and decomposed into water and carbon dioxide molecules. Production of bioactive polylactic acid scafolds that are able to chemically bond with hos cells after in vivo implantation is a very new method in cell therapy. This method has a great impact on the process and speed of repair of various tissues such as urethral tissue, abdominal wall tissue, periodontal ligament, heart tissue, corneal tissue, bladder tissue, vascular tissue, tendon tissue, cartilage tissue, skin tissue, nerve tissue, and bone tissue. In this article, the lates and mos prominent research of clinical scientiss in the world in 2020 and 2021, in order to produce bioactive polylactic acid scafolds for regeneration of body tissues is briefy reviewed.

The feld of drug delivery is a very hot research area as it afects the life of millions of patients every year. Although pharmaceutical agents can be adminisrated in diferent ways, the efectiveness of certain drug delivery sysem (DDS) is directly related to the method of their adminisration. Polyurethanes are one of the mos important classes of polymers, that play an essential role in the development of many diferent biomedical devices due to their exceptional compatibility, mechanical properties and fexibility. Polyurethanes are formed by the reaction reviewed of isocyanates and diols to produce urethane-bonded polymers (-NH-COO-) in their main chain, which is similar to the peptide bonds in the sructure of proteins. Because of this similarity, they have also been used as part of the human body, such as dialysis membranes, intra-aortic balloons, heart valves, temporary scafolds and breas implants. There are many types of polyurethane sructural blocks available that allow the chemical and physical properties of polyurethane to be tailored to their intended applications, especially in the medical and pharmaceutical felds. In this paper, the synthesis and properties of polyurethane, sructure, thermal sability, hardness, solvent resisance, drug delivery, mechanical properties as well as biodegradability and biocompatibility with special emphasis on the application of the polymer in controlled release of drugs and delivery to the target tissue were.

One of the important goals of the pharmaceutical indusry is to increase the therapeutic efectiveness of drugs for  patients and reduce their side efects. In order to fulfll these targets, the drugs should be prescribed to each patient individually and in accordance with the patient's genetic information, because in each patient, the amount of drug absorption, the time that drug reaches the target tissue and the efect of drug on the patient's organ are diferent. This clearly shows the importance of personalized medicine. Medication in personalized medicine leads to patient comfort and adaptation. The production of personalized drugs with 3D printing technology has been possible, which has  received a lot of attention in recent years. Using this technology, it is possible to design and made drugs with diferent shapes and color for children and load some drugs in one dosage (polypill) for elderly people. Also, using this  technology, the drug release pattern can be adjused by changing the thickness or type of polymer layer. The drug  release profle can be designed in such a way that each drug in polypill has special release pattern. In this article, after explaining the importance of personalized drug delivery, some encapsulated drugs in polymeric carriers are discussed. Then, some new drug delivery sysems, such as wound dressings and microsyringes produced with this technology in recent years, are briefy reviewed.

Today, the growing need for energy due to the development of human societies is inevitable. Given the limited energy resources of the planet as well as the environmental pollution caused by the consumption of fossil fuels, the use of solar energy as a clean energy is an undeniable necessity. The use of photovoltaic converters, i.e. solar cells, is one of the efective solutions for the optimal use of this huge source of energy. So far, several sudies have been conducted on the design, manufacture and optimization of solar cells. One of the mos invaluable approaches is machine learning methods. Machine learning is considered as a new branch of academic science that provides valuable new information by processing exising data. Areas of application of machine learning in the design and manufacture of polymer solar cells are divided into three general categories: predicting the solar cells efciency, selecting appropriate materials, and optimizing the manufacturing process. In this article, we have tried to briefy introduce the machine learning methods and then explain their applications in the feld of designing and manufacturing solar cells. Due to several research activities, this article is limited to peer-reviewed articles in the years 2019 and 2020.

The sudy of degradation kinetics of epoxy nanocomposites is very important because it can determine the temperature range and service life of the sysem. Degradation kinetics modeling has become widely used as an essential tool for engineers to predict the thermal durability of materials before their usage in indusry, leading to reduced coss and product development, manufacturing coss, time and quality of the designed product. Dispersion and disribution of clay nanoparticles in epoxy resin matrix are two important factors in the physical and mechanical properties of epoxy nanocomposites. Also, the inhibitory properties of clay nanoparticles or layered silicates agains hydrogen and oxygen, as well as the type of sructure can cause thermal sability of epoxy resin. Surface modifcation of the clay nanoparticles could play a delaying role in the degradation reaction of epoxy nanocomposites. The content of the added clay nanoparticles and the type of production process  are two important factors in invesigating the degradation kinetics of epoxy resin in the presence of clay nanoparticles. In this paper, the efect of modifed and unmodifed clay nanoparticles on the degradation kinetics of epoxy resin and diferent models of degradation kinetics, activation energy, thermogravimetric analysis and weight loss percentage and the efect of diferent types of clay nanoparticles on the degradation kinetics of epoxy resin are reviewed.