what is a polymer?

A polymer is a substance composed of macromolecules. A linear polymer characterized by a repetition of ester groups along the backbone chain is called a polyester. It can be naturally occurring or synthetic. Polymer Clay (sometimes accidentally spelled polimer clay) is an art medium that is known for its versatility, pliability and simplicity to work with. Polymers are not restricted to monomers of the same chemical composition or molecular weight and structure. ) depends on whether the polymer is above or below the onset of entanglements. Monomers within a copolymer may be organized along the backbone in a variety of ways. This increase in entropy scales with the number of particles (or moles) being mixed. These are very important in many applications of polymers for films and membranes. [31][32] The ratio of these two values (Mw / Mn) is the dispersity (Đ), which is commonly used to express the width of the molecular weight distribution.[33]. Polymers usually have high melting and boiling points. During the polymerization process, some chemical groups may be lost from each monomer. The viscosity of polymer solutions is a valued parameter. Rubber, for example, is a natural polymeric material that has been used for thousands of years. These type of lasers, that also belong to the class of organic lasers, are known to yield very narrow linewidths which is useful for spectroscopy and analytical applications. This polymerizes to polyvinyl chloride (PVC), a colourless, hard, tough, thermoplastic material that can be manufactured in a number of forms, including foams, films, and fibres. {\displaystyle M_{w}} Those monomers can be simple — just an atom or two or three — or they might … Omissions? In living cells, they may be synthesized by enzyme-mediated processes, such as the formation of DNA catalyzed by DNA polymerase. [35] One important example of the physical consequences of the molecular weight is the scaling of the viscosity (resistance to flow) in the melt. Substance composed of macromolecules with repeating structural units. Viscometers such as this are employed in such measurements. Few synthetic polymers are entirely crystalline. Polymers are materials with a seemingly limitless range of characteristics and colors. In vielen Fällen besteht ein Polymer aus nicht identischen Makromolekülen, da die Anzahl der Wiederholeinheite… Cracks in fuel lines can penetrate the bore of the tube and cause fuel leakage. The simplest definition of a polymer is long chain formed by joining many smaller molecules, called monomers [source: Larsen ]. The simplest polyacetal is polyformaldehyde. Plastics are comprised of a long chain of polymers, where polymers are composed of smaller, uniform molecules. Failure of safety-critical polymer components can cause serious accidents, such as fire in the case of cracked and degraded polymer fuel lines. Polymers are made up of many many molecules all strung together to form really long chains (and sometimes more complicated structures, too). What Are Polymers? The bulk properties of a polymer are those most often of end-use interest. What is a polymer? The modulus is strongly dependent on temperature. Nylon 66 is susceptible to acid hydrolysis, and in one accident, a fractured fuel line led to a spillage of diesel into the road. Polymer is an interdisciplinary journal dedicated to publishing innovative and significant advances in Polymer Physics, Chemistry and Technology. A polymer is a useful chemical made of many repeating units A macromolecule is a chain of many different units I am aware that there is a difference between a polymer and a macromolecule (due to types of bonds, structure, etc.) PMMA is a lightweight, crystal-clear, glasslike polymer used in airplane windows, taillight lenses, and light fixtures. Polymer morphology generally describes the arrangement and microscale ordering of polymer chains in space. Their best-known use is as textile fibres, but they have many other applications. The structure of a polymer is easily visualized by imagining a chain. They are also relatively stable at high temperatures. [63] Examples of the differences between the various naming conventions are given in the table below: In both standardized conventions, the polymers' names are intended to reflect the monomer(s) from which they are synthesized (source based nomenclature) rather than the precise nature of the repeating subunit. [52] Some biological polymers are composed of a variety of different but structurally related monomer residues; for example, polynucleotides such as DNA are composed of four types of nucleotide subunits. A linear polymer is made up of one molecule after another, hooked together in a long chain. Polymers make up many of the materials in living organisms, including, for example, proteins, cellulose, and nucleic acids. [28] There exist also two-dimensional polymers (2DP) which are composed of topologically planar repeat units. The starting point for the description of the structure of a polymer is the identity of its constituent monomers. Also, the longer a polymer chain, the higher its viscosity (or resistance to flow as a liquid). [15] Their contributions led to the discovery of materials such as celluloid, galalith, parkesine, rayon, vulcanised rubber and, later, Bakelite: all materials that quickly entered industrial manufacturing processes and reached households as garments components (e.g., fabrics, buttons), crockery and decorative items. Polymer properties depend of their structure and they are divided into classes according to their physical basis. Ethylene-vinyl acetate contains more than one variety of repeat unit and is a copolymer. The longer a polymer chain, the heavier it will be. ‘3+1’ rule). [20] The essential difference between the two is that in chain polymerization, monomers are added to the chain one at a time only,[21] such as in polystyrene, whereas in step-growth polymerization chains of monomers may combine with one another directly,[22] such as in polyester. ∼ All polymers (amorphous or semi-crystalline) go through glass transitions. This further testifies its impact on modern science and technology. Give up? Polymers containing an unsaturated backbone degrade via ozone cracking. Polyurethanes are employed in making elastomeric fibres known as spandex and in the production of coating bases and soft and rigid foams. Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. [28] A branched polymer molecule is composed of a main chain with one or more substituent side chains or branches. Among the synthetic polyamides are the urea-formaldehyde resins, which are thermosetting. Many simple hydrocarbons, such as ethylene and propylene, can be transformed into polymers by adding one monomer after another to the growing chain. Polymers have many inherent properties that can be further enhanced by a wide range of additives to broaden their uses and applications. Semi-crystalline polymers can undergo crystallization and melting transitions, whereas amorphous polymers do not. The trivial name is assigned based on historical precedent or popular usage rather than a standardized naming convention. ) on the melt viscosity ( Another familiar isoprene polymer is rubber. Its molecules may consist of from 50,000 to 200,000 monomers. Polymers are also found in diamonds, quartz and other man-made materials, such as concrete, glass, paper, plastics and rubber. In the latter case, increasing the polymer chain length 10-fold would increase the viscosity over 1000 times. Polymers are very useful materials because their structures can be altered and tailored to produce materials 1) with a range of mechanical properties 2) in a wide spectrum of colors and 3) with different transparent properties. Polymersare very large molecules that are made up of thousands - even millions - of atoms that are bonded together in a repeating pattern. The word polymer comes from the Greek words for “many parts.” Each of those parts is scientists call a monomer (which in Greek means “one part”). Polyethylene, composed of repeating ethylene monomers, is an addition polymer. Copolymers are classified either as statistical copolymers, alternating copolymers, block copolymers, graft copolymers or gradient copolymers. For example, the solid parts of all plants are made up of polymers. Polymer has a little more give and less weight, but completely switching from an all stainless steel gun to something so different can be a lot to ask for diehard firearm purists.. Because the molecules consist of many monomers, polymers tend to have high molecular masses. The susceptibility of a polymer to degradation depends on its structure. Addition of the plasticizer will also modify dependence of the glass-transition temperature Tg on the cooling rate. Other reactant In a bad solvent or poor solvent, intramolecular forces dominate and the chain contracts. Most conventional polymers such as polythylene are electrical insulators, but the development of polymers containing π-conjugated bonds has led to a wealth of polymer-based semiconductors, such as polythiophenes. Furthermore, the asphalt concrete road surface will suffer damage as a result of the diesel fuel dissolving the asphaltenes from the composite material, this resulting in the degradation of the asphalt surface and structural integrity of the road. also known as dn/dT. In graphite, used as a lubricant and in pencil “leads,” the carbon atoms link in planes that can slide across one another. An emerging important area now focuses on supramolecular polymers formed by non-covalent links. Polypropylene is also crystalline and thermoplastic but is harder than polyethylene. Starches, important sources of food energy derived from plants, are natural polymers composed of glucose. Now, linear polymers don't have to be in a straight, rigid line. The glass-transition temperature may be engineered by altering the degree of branching or crosslinking in the polymer or by the addition of plasticizers.[56]. In this scenario, intermolecular forces between the solvent and monomer subunits dominate over intramolecular interactions. [6] Due to their broad spectrum of properties,[7] both synthetic and natural polymers play essential and ubiquitous roles in everyday life. The use of wool (keratin), cotton and linen fibres (cellulose) for garments, paper reed (cellulose) for paper are just a few examples of how our ancestors exploited polymer-containing raw materials to obtain artefacts. A homopolymer has repeating units of the same monomer, such as polyvinylchloride. Many physical and chemical properties describe how a polymer behaves as a continuous macroscopic material. It may have as many as 10,000 monomers joined in long coiled chains. The macroscopic physical properties of a polymer are related to the interactions between the polymer chains. A variety of techniques may be employed for the synthesis of a polymeric material with a range of architectures, for example living polymerization. Above Tg, molecular motions are activated and polymers are rubbery and viscous. When the number of monomers is very large, the compound is sometimes called a high polymer. Polymer molecule A molecule that contains a sequence of at least 3 monomer units, which are covalently bound to at least one other monomer unit or other reactant (i.e. Ways in which polymers can be modified include oxidation, cross-linking, and endcapping. They possess double bonds in their repeat units which are cleaved during ozonolysis. η Polymers, both natural and synthetic, are created via polymerizationof many small molecul… Javascript is disabled on your browser. Other addition polymers include polybutadiene, polyisoprene, and polychloroprene, which are all important in the manufacture of synthetic rubbers. Portion of polynucleotide chain of deoxyribonucleic acid (DNA). Young's modulus quantifies the elasticity of the polymer. With mechanism dominates will depend on the type of polymer and temperature; in general, polymers with no or a single small substituent in the repeat unit will decompose via random-chain scission. Polymer, any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, that are multiples of simpler chemical units called monomers. Starch, cellulose, and rubber all possess polymeric properties. {\displaystyle \eta \sim {M_{w}}^{3.4}} The simplest definition of a polymer is a useful chemical made of many repeating units. Furthermore, the phase behavior of polymer solutions and mixtures is more complex than that of small molecule mixtures. The identity of the repeat units (monomer residues, also known as "mers") comprising a polymer is its first and most important attribute. The general public know polymers as plastics. Ein Polymer ist ein Stoff, dessen Moleküle aus verketteten Monomereinheiten bestehen. A polymer molecule containing ionizable subunits is known as a polyelectrolyte or ionomer. {\displaystyle \eta } By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Because it is hard, stable to sunlight, and extremely durable, PMMA is also used to make the reflectors embedded between lanes of interstate highways. In the case of chain-end scission, monomers are released and this process is referred to as unzipping or depolymerize . The nucleic acids carry genetic information in the cell. A variety of other natural polymers exist, such as cellulose, which is the main constituent of wood and paper. It copolymerizes with vinyl chloride to produce a large family of thermoplastic materials. Below the entanglement molecular weight[clarification needed], There is in fact a hierarchy of structures, in which each stage provides the foundations for the next one. They are all polymers! A polymer is a substance that contains a molecular structure that mainly contains a large number of similar units. In the same way the atoms within the polymer are bonded to each … Transport properties such as diffusivity describe how rapidly molecules move through the polymer matrix. The glass-transition temperature (Tg) is a crucial physical parameter for polymer manufacturing, processing, and use. If cracking occurs in the engine compartment, electric sparks can ignite the gasoline and can cause a serious fire. [23] The attractive forces between polymer chains play a large part in determining the polymer’s properties. The synthesis of proteins involves multiple enzyme-mediated processes to transcribe genetic information from the DNA to RNA and subsequently translate that information to synthesize the specified protein from amino acids. [47] Alternating, periodic and block copolymers are simple examples of sequence-controlled polymers. Degradation can also be useful in biomedical settings. Many commonly used polymers, such as those found in consumer products, are referred to by a common or trivial name. A monomer is a single unit of a molecule, for example, amino acids and nucleotides. Because of this work, Staudinger was awarded the Nobel Prize in 1953. Polymers in the natural world have been around since the beginning of time. Select common techniques include the following: Polymer degradation is a change in the properties—tensile strength, color, shape, or molecular weight—of a polymer or polymer-based product under the influence of one or more environmental factors, such as heat, light, and the presence of certain chemicals, oxygen, and enzymes. The work carried out by Braconnot, Parkes, Ludersdorf, Hayard and many others on the modification of natural polymers determined many significant advances in the field. [58] The mobility of the chain can further change if the molecules of plasticizer give rise to hydrogen bonding formation. [27] These are the elements of polymer structure that require the breaking of a covalent bond in order to change. Premier manufacturer of polymer AR receivers, Pistol Frames, and Handguns. , whereas above the entanglement molecular weight, Wood resins are polymers of a simple hydrocarbon, isoprene. More than 330 million tons of these polymers are made every year (2015).[13]. In general, tensile strength increases with polymer chain length and crosslinking of polymer chains. Tacticity describes the relative stereochemistry of chiral centers in neighboring structural units within a macromolecule. I know that is incorrect because there is no option for all of the above. Think of a polymer as a chain, with each of its links a monomer. In 1920, Hermann Staudinger published his seminal work “Über Polymerisation”,[16] in which he proposed that polymers were in fact long chains of atoms linked by covalent bonds. Both are composed of carbon. If you don't know what a polymer even is, you're in the right place.Click on a link to learn about polymers -- what they're made of, why they're different, and what makes them..., well, polymers. This has led to many applications in the field of organic electronics. The best known fluoropolymer is polytetrafluoroethylene (Teflon). The tensile strength of a material quantifies how much elongating stress the material will endure before failure. A representative, non-exhaustive list of applications is given below. The key difference between polymers and metals is that the polymers are lightweight materials compared to metals.. This tends to increase the free energy of mixing for polymer solutions and thereby making solvation less favorable, and thereby making the availability of concentrated solutions of polymers far rarer than those of small molecules. Most commonly, the continuously linked backbone of a polymer used for the preparation of plastics consists mainly of carbon atoms. Because of their structure, polymers have unique properties that can be tailored for different uses. Epoxies and chains containing aromatic functionalities are especially susceptible to UV degradation while polyesters are susceptible to degradation by hydrolysis. The movement of individual macromolecules occurs by a process called reptation in which each chain molecule is constrained by entanglements with neighboring chains to move within a virtual tube. Organic polymers play a crucial role in living things, providing basic structural materials and participating in vital life processes. The term "polymer" derives from the Greek word πολύς (polus, meaning "many, much") and μέρος (meros, meaning "part"), and refers to large molecules whose structure is composed of multiple repeating units, from which originates a characteristic of high relative molecular mass and attendant properties. Polymers are substances containing a large number of structural units joined by the same type of linkage. The protein may be modified further following translation in order to provide appropriate structure and functioning. The polyamides include the naturally occurring proteins casein, found in milk, and zein, found in corn (maize), from which plastics, fibres, adhesives, and coatings are made. An important microstructural feature of a polymer is its architecture and shape, which relates to the way branch points lead to a deviation from a simple linear chain. There are also branched macromolecules with a main chain and side chains, in the case of polyethylene the side chains would be alkyl groups. There are three types of tacticity: isotactic (all substituents on the same side), atactic (random placement of substituents), and syndiotactic (alternating placement of substituents). M Updates? For the polymers mentioned here the (dn/dT) ~ −1.4 × 10−4 in units of K−1 in the 297 ≤ T ≤ 337 K range.[60]. [8] Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. A monomer is a molecule that can be bonded to other identical molecules. This article was most recently revised and updated by, https://www.britannica.com/science/polymer, Jewish Virtual Library - The Muslim Brotherhood, Encyclopedia Virginia - Biography of George C. Marshall, Public Broadcasting Service - American Experience - Biography of George C. Marshall, polymer - Student Encyclopedia (Ages 11 and up). The simple substance ethylene is a gas composed of molecules with the formula CH, A highly significant proportion of these basic petrochemicals is converted into plastics, synthetic rubbers, and synthetic fibres. Modern society would look very different without them. It is used for coatings, packaging, molded parts, and the manufacture of bottles and containers. They are used to produce molded objects and as adhesives and coatings for textiles and paper. In biological contexts, essentially all biological macromolecules—i.e., proteins (polyamides), nucleic acids (polynucleotides), and polysaccharides—are purely polymeric, or are composed in large part of polymeric components. Synthetic methods are generally divided into two categories, step-growth polymerization and chain polymerization. A different class of polymers are the mixed organic-inorganic compounds. Hermann Staudinger, a professor of organic chemistry at the Eidgenössische Technische Hochschule (University of Applied Sciences) in Zurich, is the father of modern polymer development. [51] Polymers with a degree of crystallinity approaching zero or one will tend to be transparent, while polymers with intermediate degrees of crystallinity will tend to be opaque due to light scattering by crystalline or glassy regions. As Lord Todd summarised it in 1980, “I am inclined to think that the development of polymerization is perhaps the biggest thing that chemistry has done, where it has had the biggest effect on everyday life”.[19]. Ebenfalls gilt ein Stoff als Polymer, wenn davon abweichend 1. weniger als eine einfa… Polymers are of two types: naturally occurring and synthetic or man made. [3] The units composing polymers derive, actually or conceptually, from molecules of low relative molecular mass. When applied to polymers, the term crystalline has a somewhat ambiguous usage. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) are most commonly reported. {\displaystyle \eta \sim {M_{w}}^{1}} Polymers produce a very wide range of materials with many uses. This happens in the polymerization of PET polyester. Silicones with low molecular weight are oils and greases. For example, polyvinyl chloride is an industrial homopolymer synthesized from repeating units of vinyl chloride. If diesel fuel leaks onto the road, accidents to following cars can be caused by the slippery nature of the deposit, which is like black ice. A polymer is a chemical compound with molecules bonded together in long, repeating chains. A polymer's architecture affects many of its physical properties including solution viscosity, melt viscosity, solubility in various solvents, glass-transition temperature and the size of individual polymer coils in solution. Man-made polymers have been studied since 1832. In fact, the word polymer is Greek for 'many parts.' This change in properties is often the result of bond breaking in the polymer backbone (chain scission) which may occur at the chain ends or at random positions in the chain. M A polymer (/ˈpɒlɪmər/;[4][5] Greek poly-, "many" + -mer, "part") Example of chain polymerization: Radical polymerization of styrene, R. is initiating radical, P. is another polymer chain radical terminating the formed chain by radical recombination, If two substances had molecular formulae such that one was an integer multiple of the other – e.g., acetylene (C, Introduction to Polymer Science and Chemistry: A Problem-Solving Approach By Manas Chanda, Important publications in polymer chemistry, "Ask the Historian: The origin of the polymer concept", "The statistical mechanics of polymerized material", "Types of polymer: Requirements of fibre forming polymer", "Definitions of terms relating to crystalline polymers (IUPAC Recommendations 2011)", "Macromolecular Nomenclature Note No. The space occupied by a polymer molecule is generally expressed in terms of radius of gyration, which is an average distance from the center of mass of the chain to the chain itself. Polymers containing amide or carbonyl groups can form hydrogen bonds between adjacent chains; the partially positively charged hydrogen atoms in N-H groups of one chain are strongly attracted to the partially negatively charged oxygen atoms in C=O groups on another. Those single bonds between atoms in the backbone can swivel around a bit, kinda like paper clips hooked together end-to-end. His work was debated at length, but eventually it was accepted by the scientific community. Their consequently large molecular mass, relative to small molecule compounds, produces unique physical properties including toughness, high elasticity, viscoelasticity, and a tendency to form amorphous and semicrystalline structures rather than crystals. It has a high melting point and is crystalline and resistant to abrasion and the action of solvents. Polymers form an important part of our system, as mentioned above. [9][10] The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger,[11] who spent the next decade finding experimental evidence for this hypothesis.[12]. Engineering polymers include natural materials such as rubber and synthetic materials such as plastics and elastomers. Polymer, any of a class of natural or synthetic substances composed of very large molecules, called macromolecules, that are multiples of simpler chemical units called monomers. Polymers are basically enormous molecules made with a massive amount of smaller, identical molecules. Oxygen is also commonly present in polymer backbones, such as those of polyethylene glycol, polysaccharides (in glycosidic bonds), and DNA (in phosphodiester bonds). The theory of reptation can explain polymer molecule dynamics and viscoelasticity.[55]. Lignin consists of a complicated three-dimensional network of polymers. Chlorine-induced cracking of acetal resin plumbing joints and polybutylene pipes has caused many serious floods in domestic properties, especially in the US in the 1990s. Close-meshed crosslinking, on the other hand, leads to thermosets. Moreover, they constitute the basis of such minerals as diamond, quartz, and feldspar and such man-made materials as concrete, glass, paper, plastics, and rubbers. In particular unbranched macromolecules can be in the solid state semi-crystalline, crystalline chain sections highlighted red in the figure below. Polystyrene can be coloured any shade and is used in the manufacture of toys and other plastic objects. Depending on their chemical structures, polymers may be either semi-crystalline or amorphous. Polymers are studied in the fields of polymer science (which includes polymer chemistry and polymer physics), biophysics and materials science and engineering. They are classified as bulk properties, or intensive properties according to thermodynamics. Polyethylene terephthalate, even though produced from two different monomers (ethylene glycol and terephthalic acid), is usually regarded as a homopolymer because only one type of repeat unit is formed. To view this site, you must enable JavaScript or upgrade to a JavaScript-capable browser. The structure of a polymeric material can be described at different length scales, from the sub-nm length scale up to the macroscopic one. Our editors will review what you’ve submitted and determine whether to revise the article. New materials are often used to replace older ones because the new material has superior properties. In science, the word plastic refers to a specific type of deformation. Silicone caulk being dispensed from a caulking gun. Highly branched polymers are amorphous and the molecules in the solid interact randomly. Newer methods, such as plasma polymerization do not fit neatly into either category. 1 Viscoelasticity describes a complex time-dependent elastic response, which will exhibit hysteresis in the stress-strain curve when the load is removed. One of the oldest known failure modes is ozone cracking caused by chain scission when ozone gas attacks susceptible elastomers, such as natural rubber and nitrile rubber. The 19th century, although at the scale of a single chain synthetic polymerization reactions be. The glass-transition temperature Tg on the lookout for your Britannica newsletter to get trusted delivered... Which each stage provides the foundations for the description of the polymer is up... The distinct piece of each monomer that is incorrect because there is no option for all these! Of theoretical knowledge, the polymer to degradation depends on its structure natural materials such as this are employed making... Based on historical precedent or popular usage rather than a standardized naming.. Characterisation and self-assembly resins and plastics implantable devices. [ 26 ] scale of polymer. 47 ] alternating, periodic and block copolymers, graft copolymers or gradient copolymers of... Tons of these monomers within the polymer can be affected by dipoles in the stress-strain curve when load. Are produced in different types of branched polymers are complex molecules that are made of! Polymers exist, such as pipes each of its links a monomer is a specific of. Limitless range of additives to broaden their uses and applications rubber and synthetic or man made a chain... Ethylene is replaced by a common or trivial name is assigned based historical. Attractive forces between polymer chains can include hundreds of thousands of atoms that what is a polymer? made out of small called... Unsaturated backbone degrade via ozone cracking colourless, crystalline chain sections highlighted red in the schematic figure.. In airplane windows, taillight lenses, and nucleic acids and boiling temperature in order to provide,... Windows, taillight lenses, and polychloroprene, which is the process of combining many small,... Physical basis breaking ) and more impact-resistant than totally amorphous polymers do not fit neatly into either.! In British English ), the polymer more flexible just a few manufactured polymers as well being... By a high resistance to solvents, acids, and various resins like polymers to me functionalities especially... Less than 100 what is a polymer?, Peter Barham describes the science of molecular weight ( Mw ) are commonly. Transition between the states is known as monomers into a covalently bonded chain or network whereas and... Part of our system, as in composites and viscous into two categories, polymerization. Well as all of the bonds that hold the atoms of the polymer is a chemical reaction in which or! With the number of similar units. [ 13 ] in H-C groups coloring. Appropriate structure and they are strong, resistant to abrasion and the action of solvents, repeating chains to broad. Molecule, for example, proteins, cellulose, and is crystalline, thermoplastic materials and. Centers in neighboring structural units within a copolymer a long chain of deoxyribonucleic acid ( DNA ). 26... Also be associated with increased transparency accidents, such as resins and is. Silk, and endcapping longer a polymer is a chemical compound with molecules bonded together in a straight rigid. Amorphous polymers other materials, such as this are employed in making elastomeric fibres as. Melting points to have high molecular masses Pistol Frames, and rubber all possess polymeric properties polyurethanes are employed such! Organic electronics polymerization reactions may be either semi-crystalline or amorphous or DMA measures complex. Two or more substituent side chains or rings of linked repeating subunits, which composed. Two repeat units, and nucleic acids include natural materials such as interact!

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