فصلنامه بسپارش
سال یازدهم شماره 2 (پیاپی 39، تابستان 1400)

D eep eutectic solvents (DES) are an alternative for ionic liquids (ILs). These solvents are biodegradable, non- or low-toxic compounds that obtained via simple and convenient way. They are usually prepared by complexing of a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD), forming a deep eutectic mixture, in such a way that the melting point of the  mixture is much lower than the melting points of each component. The recent discovery of natural deep eutectic solvents (NADES) has accelerated their use as an alternative to conventional organic solvents, which are inherently toxic and highly volatile. Polysaccharides are the most abundant natural polymers and are considered as prospective starting resources for the production of green materials and replacement of non-biodegradable plastics. However, films made from pure polysaccharides are usually brittle and demonstrate poor mechanical properties, that limit their use.This has led to to the development of polysaccharide-based materials modified either chemically or by the addition of reinforcing fillers and plasticizers. To date, NADES have been used not only in the extraction, separation or purification of some specific biopolymers, but also as components of polysaccharide-based materials, e.g. plasticizers, compatibilizers or modifiers. NADESs are used as plasticizer, mainly for starch films, however it is also used for cellulose derivatives, chitosan, agar and agarose. In this paper, the potential application of NADES as green, inexpensive and sustainable plasticizers in the production of natural polymer films is reviewed.

D ue to their hydrophilic network and their high ability to absorb and retain large amounts of water, hydrogels are widely used in medicine, industry, and the environment for different applications such as tissue engineering, drug delivery, and adsorption of pollutants. In addition to synthetic materials, hydrogels can be made from non-toxic, highly biocompatible, and biocompatible bio-based compounds. Recently, Diels-Alder cycloaddition reaction has been used to produce hydrogels with improved properties. Following Diels-Alder reaction, a six-membered ring is formed by the [4+2] cycloaddition between an electron-rich diene and an electron-deficient dienophile. To perform this reaction, no catalyst is required, and moreover no by-products are produced. Other important features of Diels-Alder reactions include insensitivity to various functional groups and thermal reversibility through retro-Diels-Alder reaction. However, by using the Diels-Alder reaction, it is possible to produce biocompatible bio-based hydrogels with an enhanced performance like stimulus-responsivity, self-healing property, and in-situ forming ability for a variety of applications. In this article, after a brief review of hydrogels and click reactions, recent studies and their objectives for the preparation of various biobased hydrogels using Dils-Alder reactions are discussed.

Tissue engineering is a novel approach in treatment, in which, three important factors of cell, molecule signals, and scaffolds play a vital role. Nowadays, tissue engineering scientists use nanofibrous scaffolds to treat different diseases, regenerate and replace different body tissues, so as to simulate native tissues, as well as making progress and development in nano fibrous scaffolds engineering studies. To conduct the aforementioned studies, electrospinning is preferred out of various routs, due to its simplicity and cost-effectiveness in fabrication of structures that make the production of micro/nanofibers with a wide range of compositions and forms feasible. Moreover, using various types of biomolecules, biodrugs, and growth factors that are incorporated with in these fibers, would make it possible to improve cell response and treatment yield in tissue engineering processes, along with a suitable control and conduction of the process by selecting a suitable method of molecule loading. Although, there are many challenges regarding loading and controlled delivery of biomolecules through electrospun micro/nanofibers, but they have the potential ability to enhance the drug and growth factor delivery for tissue engineering and drug therapy. In addition, these micro/nanofibers can also be utilized as releasing scaffolds in engineering and medical science.

F or more than sixty years, thousands of patents and articles have been published annually on various manufacturing methods of Ziegler-Natta catalysts and comparing the properties and performance of the obtained catalysts. However, a closer look at these documents reveals that the basic and commercial methods of manufacturing these catalysts may be very limited and that other methods are either not commercializable or are merely subsets of these original methods. In this paper, by reviewing the wide range of numerous patents patented over the past four decades, the main production methods of commercial Ziegler-Natta magnesium-titanium catalysts are categorized based on the morphology of the obtained catalyst. The morphology of Ziegler-Natta catalysts can be divided into two categories: spherical morphology and non-spherical morphology. The morphology of Ziegler-Natta catalysts is one of the most important variables that determines the possibility of using a special catalyst in the polymerization process (gas phase or suspension). Catalysts with spherical morphology can be produced by commercial methods of emulsion, impregnation, and spray drying. In contrast, catalysts with non-spherical morphology can also be produced by commercial methods of reactive precipitation and support conversion

The ever-increasing regulations within the adhesives industry and the continuous demand for more sustainability, have led to the development of environmentally more suitable alternatives to petroleum-based pressure-sensitive adhesives (PSAs). This review provides an overview of the current strategies and methods to develop sustainable, acrylic PSAs derived from renewable resources, such as vegetable oil, lignin, carbohydrates and terpenes. Herein, we emphasize some of the key concepts in the literature within the past decades, which paved the way to the current focus of improving the adhesive properties by employing the full array of natural building blocks. In this context, some recent strategies that give tailor-made adhesive properties to PSAs are also discussed, in view of the desired application. With this critical insight on the large set of research efforts in the context of biosourced acrylic PSAs, we aim to provide a guide for new researchers in this highly emerging field

P atents are one of the most important types of scientific and technological products that contain valuable information about invention, inventor or co-inventors, assignee, classification (IPC, CPC or ...), etc. This kind of information is often not published in journals and other information sources. There are databases dedicated to patents that collect patent information. Access to some of them, such as USPTO and WIPO database is free and others, such as the Derwent database, require subscription. In recent years, some scholarly and citations databases, usually dedicated to providing data on scientific works such as articles, books, etc., have also covered patents. These databases are available for free and subscription and can provide sophisticated search tools which allow simple search, advanced search, semantic search or patent number search, name of materials and chemical compounds and other search methods to obtain the required information from patents. Using advanced tools, it is possible to visualize and analyze patents to understand the development path of certain technologies. In this article, the most important databases providing patent information are introduced. These databases include lenz, Orbit, chemical abstracts service (SciFinder and PatentPAK), etc.