Polymers from carbon dioxide: Polycarbonates,polyurethanes

The world polymer industry claims over 2 million tons per year, though most synthetic polymers use petroleum feedstocks, there is a growing effort to prepare polymers from renewable raw materials concerning the depleting fossil fuel resources. In this short review, we would like to emphasize the potential that CO₂ based polymers, polycarbonates and polyurethanes from copolymerization of CO₂ and epoxides, have to mitigate the above concerns, where the newly developed metal catalyst systems allow not only their high efficient synthesis, significant advances have been achieved in stereo-controlled copolymerization. It is also noteworthy that the physical and chemical properties of CO₂ based polymers may be tailored, which help to pave the way from their lab curiosities to practical application, as new applications have been realized such as biodegradable disposal bags, and hydrolysis and oxidation resistant water borne adhesives.     

GRAFT COPOLYMERIZATION OF VINYL MONOMERS ONTO JUTE FIBERS

Abstract

Among the various types of copolymerization, graft copolym-erization has attracted considerable attention among applied polymer chemists. Graft copolymerization is a process of copolymerization of one kind of monomer in its polymeric state with another polymer which may be either synthetic or natural. So a graft copolymer is a high polymer whose molecule consists of two or more polymeric parts of different composition, chemically united together. Graft copolymerization onto textile fibers is a challenging field of research with unlimited future prospects [1-10]. This is attractive to chemists as a means of modifying macromolecules since, in general, degradation is minimized. The desirable properties of the polymer are retained, and copolymerization Drovides additional properties throuerh the added polymer.     

Chemical modification of natural polymers in China

Abstract

This paper introduces the main Chinese research work on the chemical modification of natural polymers including silk, Chinese lacquer, gutta-percha, cellulose, and chitin. The following aspects of this research work are emphasized: research on the mechanism of graft copolymerization of vinyl monomer onto natural polymers, research on overcoming the defects of natural polymers to allow further application by chemical modification, and research on exploring new applications of natural polymers.     

Graft Copolymers

The preparation of graft copolymers is a domain of polymer chemistry that has received considerable interest. Grafting of vinyl monomers to natural and synthetic polymers by means of chemical or radiation-initiated polymerization has been suggested as a potentially good means of altering the properties of the base polymer. Graft polymerization is different from random or block copolymerization in that it leaves the main polymeric backbone essentially intact. A graft copolymer may combine some of the characteristic properties of each polymer or have properties entirely different from either of the components. Hence such products made of selected polymer combinations can have highly specific properties tailor-made for a particular application.     

蛋白质接枝共聚研究进展

接枝共聚是一种有效的化学修饰方法,经过接枝改性后,高分子化合物的物理、机械和化学性质都能得到改善。文章从引发体系、接枝单体两个方面综述了酪蛋白和丝素蛋白的接枝共聚改性机理以及接枝产物的结构和性能。接枝反应中引发剂浓度和接枝单体浓度都有一个最佳值,接枝产物的热性能和力学性能都有所提高。     

Precision Biopolymers from Protein Precursors for Biomedical Applications

The synthesis of biohybrid materials with tailored functional properties represents a topic of emerging interest. Combining proteins as natural, macromolecular building blocks, and synthetic polymers opens access to giant brush‐like biopolymers of high structural definition. The properties of these precision polypeptide copolymers can be tailored through various chemical modifications along their polypeptide backbone, which expands the repertoire of known protein‐based materials to address biomedical applications. In this article, the synthetic strategies for the design of precision biopolymers from proteins through amino acid specific conjugation reagents are highlighted and the different functionalization strategies, their characterization, and applications are discussed.     

Well-defined graft copolymers: from controlled synthesis to multipurpose applications

Graft copolymers with a large number of side chains chemically attached onto a linear backbone are endowed with unusual properties thanks to their confined and compact structures, including wormlike conformation, compact molecular dimensions and notable chain end effects. Growing attention has been paid to these interesting macromolecules due to their importance in understanding the correlation between architectures and properties, as well as their potential applications. To date, the synthesis and properties of graft copolymers in both solution and bulk have been extensively investigated, along with their applications. In this tutorial review, recent advances in synthetic approaches towards the construction of well-defined graft copolymers are discussed in detail and applications of these interesting macromolecules are highlighted by selected examples.     

The Challenge for High Polymers in Medicine,Surgery, and Artificial Internal Organs

High polymers are used in medicine, surgery, or artificial organs in three ways: 1) to construct complete artificial replacements for human organs, 2) to repair, sustain, or augment function of normal organs, and 3) to provide a biochemical function.

Artificial hearts, heart lung machines, and artificial kidneys are examples of artificial organs that man is designing and building to replace natural organs. Plastics are used widely in their construction. Plastics offer a variety of properties needed for these applications, including ease of fabrication, chemical inertness, and nontoxic properties, and a wide range of physical properties in hardness, flexibility, and permeability.

Externally, as adjuncts or assists to natural organs, there are many applications of plastics in present use from clothing to glasses to dentures. Internally, the applications include vascular prostheses, check valve balls for heart valves, encapsulating resins for pacemakers, meshes and foams for reconstructive surgery, drainage tubes, and cannulae for hemodialysis. The plastics most widely used in surgical implants are polytetrafluoroethylene, polypropylene, saturated aromatic polyesters, and polysiloxanes. Growing use is being made of segmented polyurethanes, acrylics, and epoxy resins. Experimental work is under way on polyelectrolytes and various hydrogels based on polyhydroxyl compounds.

The newest class of applications of high polymers is that wherein the polymer has a definite and specific chemical interaction with the biochemistry of the body, i.e., it plays a pharmaceutical role. Examples of this include: 1) synthetic ion exchange resins for absorbing metabolites from the blood; 2) synthetic polyelectrolytes capable of absorbing specific viruses; 3) synthetic polymers such as (a) polyinosinic-polycytidylic acid (a synthetic ribonucleic acid) or (b) a copolymer of vinyl pyran and an undisclosed comonomer which promotes the production of interferon, a chemical substance normally produced by cells as an antiviral agent; and 4) synthetic natural-like polypeptides, enzymes, and chemical modifications of these with enhanced biologic activity.

The future of the use of high polymers in these applications appears to be in the earliest stages. Half a million Americans die each year of heart disease and 60,000 die of kidney disease, hence the potential for artificial versions of these organs is very large. The use of surgical devices is growing steadily. The use of polymers as drugs has not yet been tapped. In 50 years, biochemists will have a battery of synthetic polymer drugs which will cure many diseases, prevent cancer, speed wound healing, and eventually, it is hoped, provide a chemical regime for regeneration of lost limbs and organs.     

Two-Dimensional Chromatography as an Essential Means for Understanding Macromolecular Structure

Current liquid chromatography techniques allow to determine distributions of various properties for macromolecules. The polydisperse nature of macromolecules regulates the structure-property relationship and is responsible for the vast degree of fine-tuning of application properties. The understanding of macromolecular structure is fundamental for the use of polymers in increasingly specific applications. The coexistence of property distributions requires multi-dimensional (combined) chromatography methodologies. The use and implementation of two-dimensional (2D) separation methods and their benefits are described in this paper for synthetic polymers. Similar approaches have been used successfully for mapping complex natural and bio polymers.     

Graft Copolymerization of Vinyl Monomers onto Cellulose and Cellulosic Materials

Abstract

Graft copolymerization is a novel method which has wide application in synthesizing new forms of polymeric materials and also in modifying the properties of natural polymers [1,2]. Much research has been done on grafting polymeric molecules on to cellulose to produce materials of new properties intermediate between those of cellulose and those of synthetics. A variety of property changes can be imparted to cellulose through grafting without destroying the crystallinity or crystallization potential of the substrate or reducing its melting point. Some of the most dramatic changes in properties which have been brought about by grafting to cellulose are viscoelasticity, stereoregularity, hygroscopicity, water repellency, improved adhesion to a variety of substances, settability, soil resistance, bacteriocidal properties, and thermal stability.     

Nucleic Acid/Organic Polymer Hybrid Materials: Synthesis,Superstructures, and Applications

Extensive efforts have been devoted to the development of hybrid structures consisting of biomacromolecules and organic polymers connected through covalent bonds. While the combination of proteins and peptides with synthetic macromolecules has been explored in depth, far fewer examples of nucleic acid/polymer hybrids are known. In this Review we give selected examples of this exciting class of materials which can be arranged as linear block copolymer architectures, as side‐chain polymers, or as cross‐linked networks. Emphasis is placed on the fabrication of these materials as well as on their potential applications in nanoscience, diagnostics, and biomedicine.     

DNA-inspired hierarchical polymer design: electrostatics and hydrogen bonding in concert

Nucleic acids and proteins, two of nature's biopolymers, assemble into complex structures to achieve desired biological functions and inspire the design of synthetic macromolecules containing a wide variety of noncovalent interactions including electrostatics and hydrogen bonding. Researchers have incorporated DNA nucleobases into a wide variety of synthetic monomers/polymers achieving stimuli-responsive materials, supramolecular assemblies, and well-controlled macromolecules. Recently, scientists utilized both electrostatics and complementary hydrogen bonding to orthogonally functionalize a polymer backbone through supramolecular assembly. Diverse macromolecules with noncovalent interactions will create materials with properties necessary for biomedical applications.     

Lignin‐based polymers via graft copolymerization

Lignin is an important source of synthetic materials because of its abundance in nature, low cost, stable supply, and no competition to the human food supply. Lignin, a cross‐linked phenolic polymer, contains a large number of aromatic groups that can be used as a substitute for petroleum‐based aromatic fine chemicals. However, modification of lignin is necessary for its application in advanced materials due to its chemically inert nature and structural complexity. Polymeric modification of lignin via graft copolymerization represents an important avenue for modification because this method forms stable covalent bond linkages between lignin and synthetic functional polymers. In this review, we discuss recent synthetic strategies toward polymeric modification of lignin using graft copolymerization and the special properties and applications of the produced lignin copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3515–3528     

Biomedical applications of biodegradable polymers

Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. To fit functional demand, materials with desired physical, chemical, biological, biomechanical, and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

辐射接枝共聚合反应及其在有机生物医用材料制备中的应用

γ-射线辐射高分子材料表面接枝共聚合是一种绿色的、重要的有机生物材料合成制备方法. 综述了γ-射线辐射接枝共聚反应的原理、特点, 阐述了预辐射接枝共聚和共辐射接枝共聚的方法, 介绍了当前γ-射线辐射接枝共聚反应在改善有机生物医用材料的表面亲水性、生物相容性等方面的应用. 对辐射接枝共聚合制备功能药物载体研究进行了简要介绍.     

Silicification and biosilicification

Biosilicification takes place at or very close pH 7.0 and under ambient conditions of temperature and pressure in vivo. The silicic acid transporters and the proteins facilitating biosilicification in diatoms have been identified. Silica synthesis under mild conditions in vitro has been demonstrated using synthetic polymers with control over the resulting silica morphology. The results presented herein show that the silica synthesis in vitro is not specific to particular enzymes/polypeptides due to their particular chemical structure and activity but that many other synthetic macromolecules are also capable of facilitating silica formation at neutral pH. We also report the synthesis of organic-inorganic hybrid materials that have potential in optoelectronic applications.     

纤维素/明胶复合膜的超分子结构与性能

通过一种绿色的方法在NaOH/尿素水体系中制备出纤维素和明胶组成的复合膜(C/G),并且证明这两种大分子间存在强的氢键作用,导致明胶耐水性明显改善.同时,用戊二醛作为交联剂对复合膜化学交联,进一步提高其抗水性.通过红外光谱(FTIR)、紫外光谱(UV-Vis)、13C固体核磁共振谱、扫描电镜(SEM),力学和溶胀测试对...     

Graft Copolymers from Natural Polymers Using Free Radical Polymerization

The present research work deals with the surface modification of natural cellulosic polymers to develop novel materials for different applications. Natural cellulose-graft-poly (methyl acrylate) copolymers were prepared using the free radical induced graft copolymerization technique. Different reaction parameters were optimized to achieve the highest percentage of grafting of natural cellulose-graft-poly (methyl acrylate) copolymers. The natural cellulose graft copolymers were characterized by FT-IR, SEM, TGA, and physicochemical studies. For the evaluation of swelling and the physicochemical mechanism, swelling and chemical resistance studies were carried out in different solvents as well as chemicals.     

Biological–synthetic hybrid block copolymers: Combining the best from two worlds

Although biopolymers and synthetic polymers share many common features, each of these two classes of materials is also characterized by a distinct and very specific set of advantages and disadvantages. Combining biopolymer elements with synthetic polymers into a single macromolecular conjugate is an interesting strategy for synergetically merging the properties of the individual components and overcoming some of their limitations. This article focuses on a special class of biological–synthetic hybrids that are obtained by site‐selective conjugation of a protein or peptide and a synthetic polymer. The first part of the article gives an overview of the different liquid‐phase and solid‐phase techniques that have been developed for the synthesis of well‐defined, that is, site‐selectively conjugated, synthetic polymer–protein hybrids. In the second part, the properties and potential applications of these materials are discussed. The conjugation of biological and synthetic macromolecules allows the modulation of protein binding and recognition properties and is a powerful strategy for mediating the self‐assembly of synthetic polymers. Synthetic polymer–protein hybrids are already used as medicines and show significant promise for bioanalytical applications and bioseparations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1–17, 2005     

SYNTHETIC POLYMERIC AMPHOLYTES IN SOLUTION

Abstract

Polyampholytes are classified as polyelectrolytes whose macromolecules contain functional groups of acidic and basic character [1, 2]. They possess unique physicochemical properties due to the contamination of oppositely charged units in the polymer chain. The interest in studying polyampholytes arises because they include such important natural polymers as proteins and nucleic acids [3]. Biopolymers possess specific structures, functions, and properties which are fully revealed only in living organisms [4]. Nevertheless, some properties of natural polymers can be simulated by using synthetic amphoteric macromolecules.