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| | Rudy Lafrance is what people contact him when his full name is used by individuals but he doesn't like Virginia is where my property is but I have to proceed for my family I'm a credit authoriser as well as the pay continues to be really fulfilling I cannot make it my occupation actually although what I really enjoy doing is shows<br><br>[http://onlinemedication.page.tl/Homepage.htm neighborhood pharmacy] |
| |title = IUPAC definition for copolymer
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| |quote = A [[polymer]] derived from more than one species of [[monomer]].
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| Note: Copolymers that are obtained by [[copolymerization]] of two monomer species<br/>are sometimes termed bipolymers, those obtained from three monomers terpolymers,<br/>those obtained from four monomers quaterpolymers, etc.
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| <ref name=goldbook1996>
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| {{cite journal
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| |url = http://goldbook.iupac.org/C01335.html
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| |doi = 10.1351/goldbook.C01335
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| |title = Glossary of basic terms in polymer science (IUPAC Recommendations 1996)
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| |last1 = McNaught |first1 = A. D. |last2 = Wilkinson, A.
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| |journal = [[Pure and Applied Chemistry]] |volume=68 |year=1996 |pages=2287–2311
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| }}</ref>
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| '''[[Copolymer#Types of copolymers|Alternating copolymers]]''': A copolymer consisting of [[macromolecule]]s comprising<br/>two species of monomeric units in alternating sequence.
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| Note: An alternating copolymer may be considered as a [[Polymer#Monomers and repeat units|homopolymer]] derived from<br/>an implicit or hypothetical monomer.<ref name=goldbook1996>{{cite journal|title=Glossary of basic terms in polymer science (IUPAC Recommendations 1996)|journal=[[Pure and Applied Chemistry]]|year=1996|volume=68|issue=12|pages=2287–2301|doi=10.1351/goldbook.A00250|url=http://goldbook.iupac.org/A00250.html}}</ref>
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| '''[[Copolymer#Types of copolymers|Block copolymers]]''': A portion of a macromolecule, comprising many constitutional<br/>units, that has at least one feature which is not present in the adjacent portions.<ref name=goldbook1996>{{cite journal|title=Glossary of basic terms in polymer science|journal=[[Pure and Applied Chemistry]]|year=1996|volume=68|issue=12|pages=2287–2311|doi=10.1351/pac199668122287|url=http://iupac.org/publications/pac/68/12/2287/}}</ref>
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| '''[[Copolymer#Types of copolymers|Graft macromolecule]]''': A macromolecule with one or more species of<br/>block connected to the main chain as side-chains, these side-chains having constitutional<br/>or configurational features that differ from those in the main chain.<ref>{{cite journal|title=Glossary of basic terms in polymer science (IUPAC Recommendations 1996)|journal=[[Pure and Applied Chemistry]]|year=1996|volume=68|issue=12|pages=2287–2311|doi=10.1351/pac199668122287|url=http://pac.iupac.org/publications/pac/pdf/1996/pdf/6812x2287.pdf}}</ref>
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| }}
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| [[Image:Lfg polymer milk (cropped).jpg|thumb|right|150px|Vinyl Copolymer Milk]]
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| A '''heteropolymer''' or '''copolymer''' is a [[polymer]] derived from two (or more) [[monomer]]ic species, as opposed to a [[homopolymer]] where only one monomer is used.<ref>{{cite book|author=Odian, G. |title=Principles of Polymerization|publisher=Wiley-Interscience|year=2004|chapter=6|isbn=0-471-27400-3|url=http://books.google.com/?id=6cjgZbFHI4kC&pg=PA464|page=464}}</ref> '''Copolymerization''' refers to methods used to chemically synthesize a copolymer.
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| Commercially relevant copolymers include [[ABS plastic]], [[Styrene/butadiene co-polymer|SBR]], [[Nitrile rubber]], [[styrene-acrylonitrile]], styrene-isoprene-styrene (SIS) and [[ethylene-vinyl acetate]].
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| ==Types of copolymers==
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| [[Image:Copolymers.svg|right|thumb|350px|Different types of copolymers]]
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| Since a copolymer consists of at least two types of constituent units (also [[structural unit]]s), copolymers can be classified based on how these units are arranged along the chain.<ref>{{cite journal|title=Glossary of Basic Terms in Polymer Science|journal=Pure Appl. Chem.|year= 1996|volume=68|pages=2287–2311|doi=10.1351/pac199668122287|last1=Jenkins|first1=A. D.|last2=Kratochvíl|first2=P.|last3=Stepto|first3=R. F. T.|last4=Suter|first4=U. W.|issue=12}}</ref> These include:
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| *'''Alternating copolymers''' with regular alternating A and B units (2)
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| *'''Periodic copolymers''' with A and B units arranged in a repeating sequence (e.g. (A-B-A-B-B-A-A-A-A-B-B-B)<sub>n</sub>)
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| *'''Statistical copolymers''' are copolymers in which the sequence of monomer residues follows a statistical rule. If the probability of finding a given type monomer residue at a particular point in the chain is equal to the mole fraction of that monomer residue in the chain, then the polymer may be referred to as a truly '''random copolymer'''<ref name="PC14">Painter P. C. and Coleman M. M., ''Fundamentals of Polymer Science'', CRC Press, 1997, p 14.</ref> (3).
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| *'''Block copolymers''' comprise two or more homopolymer subunits linked by covalent bonds (4). The union of the homopolymer subunits may require an intermediate non-repeating subunit, known as a '''junction block'''. Block copolymers with two or three distinct blocks are called '''diblock copolymers''' and '''triblock copolymers''', respectively.
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| Copolymers may also be described in terms of the existence of or arrangement of '''branches''' in the polymer structure. '''Linear copolymers''' consist of a single main chain whereas '''branched copolymers''' consist of a single main chain with one or more polymeric side chains.
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| Other special types of branched copolymers include '''star copolymers''', '''brush copolymers''', and '''comb copolymers'''. In [[gradient copolymers]] the monomer composition changes gradually along the chain.
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| {{anchor|terpolymer}}
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| A '''terpolymer''' is a copolymer consisting of three distinct [[monomer]]s. The term is derived from ''ter'' (Latin), meaning thrice, and [[polymer]].
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| *'''Stereoblock copolymers'''
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| [[File:Stereobl.png|thumb|left]]
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| A special structure can be formed from one monomer where now the distinguishing feature is the [[tacticity]] of each block.
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| ===Graft copolymers===
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| '''Graft copolymers''' are a special type of branched copolymer in which the side chains are structurally distinct from the main chain. The [[:File:Copolymers.svg|illustration]] (5) depicts a special case where the main chain and side chains are composed of distinct homopolymers. However, the individual chains of a graft copolymer may be homopolymers or copolymers. Note that different copolymer sequencing is sufficient to define a structural difference, thus an A-B diblock copolymer with A-B alternating copolymer side chains is properly called a graft copolymer.
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| For example, suppose we perform a [[radical polymerization|free-radical polymerization]] of [[styrene]] in the presence of [[polybutadiene]], a [[synthetic rubber]], which retains one reactive C=C [[covalent bond|double bond]] per [[residue (chemistry)|residue]]. We get [[polystyrene]] chains growing out in either direction from some of the places where there were double bonds, with a one-carbon rearrangement. Or to look at it the other way around, the result is a polystyrene backbone with polybutadiene chains growing out of it in both directions. This is an interesting copolymer variant in that one of the ingredients was a polymer to begin with.
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| As with block copolymers, the quasi-[[composite material|composite]] product has properties of both "components". In the example cited, the rubbery chains absorb energy when the substance is hit, so it is much less brittle than ordinary polystyrene. The product is called high-impact polystyrene, or HIPS.
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| ===Block copolymers===
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| A special kind of copolymer is called a "block copolymer". Block copolymers are made up of blocks of different [[polymerized]] [[monomers]].<ref>[http://www.princeton.edu/~polymer/block.html Polymer Research Laboratory] (Princeton.edu accessed Aug 15, 2008)</ref> For example, PS-b-PMMA is short for polystyrene-b-poly([[methyl methacrylate]]) and is usually made by first polymerizing [[styrene]], and then subsequently polymerizing MMA from the reactive end of the polystyrene chains. This polymer is a "diblock copolymer" because it contains two different chemical blocks. Triblocks, tetrablocks, multiblocks, etc. can also be made. Diblock copolymers are made using [[living polymerization]] techniques, such as atom transfer free radical polymerization ([[ATRP (chemistry)|ATRP]]), reversible addition fragmentation chain transfer ([[RAFT (chemistry)|RAFT]]), [[ring-opening metathesis polymerization]] (ROMP), and living cationic or living anionic [[living polymerization|polymerization]]s.<ref>Hadjichristidis N., Pispas S., Floudas G. Block copolymers: synthetic strategies, physical properties, and applications – Wiley, 2003.</ref> An emerging technique is [[chain shuttling polymerization]]. The most powerful strategy to prepare block copolymers is the chemoselective stepwise coupling between polymeric precursors and heterofunctional linking agents.<ref>{{cite journal|doi=10.1002/marc.200700127|url=http://www3.interscience.wiley.com/cgi-bin/fulltext/114280481/PDFSTART|title=Universal Methodology for Block Copolymer Synthesis|year=2007|last1=Bellas|first1=Vasilios|last2=Rehahn|first2=Matthias|journal=Macromolecular Rapid Communications|volume=28|pages=1415|issue=13}}</ref> This method enables access to peculiarly exotic structures such as tetrablock quaterpolymers ABCD.<ref>{{cite journal|doi=10.1002/macp.200800463|title=Block Copolymer Synthesis via Chemoselective Stepwise Coupling Reactions|year=2009|last1=Bellas|first1=Vasilios|last2=Rehahn|first2=Matthias|journal=Macromolecular Chemistry and Physics|volume=210|pages=320|issue=5}}</ref>
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| Recent research in block copolymers suggests that they may be useful in creating self-constructing fabrics with potential utility in semiconductor arrays (for example, computer memory devices) by assembling fine details atop a structured base created using conventional [[microlithography]] methods.<ref>[http://www.networkworld.com/community/node/31115 Self-growing material promises chip, storage advances] (NetworkWorld accessed Aug 15, 2008)</ref>
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| ====Phase separation====
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| [[File:Sbs block copolymer.jpg|thumb|right|SBS block copolymer in [[Transmission electron microscopy|TEM]]]]
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| Block copolymers are interesting because they can "microphase separate" to form periodic [[nanostructures]], as in the styrene-butadiene-styrene block copolymer shown at right. The polymer is known as [[Kraton (polymer)|Kraton]] and is used for shoe soles and [[adhesive]]s. Owing to the microfine structure, the transmission electron microscope or [[Transmission electron microscopy|TEM]] was needed to examine the structure. The butadiene matrix was stained with [[osmium tetroxide]] to provide contrast in the image. The material was made by [[living polymerization]] so that the blocks are almost [[monodisperse]], so helping to create a very regular microstructure. The [[molecular weight]] of the polystyrene blocks in the main picture is 102,000; the inset picture has a molecular weight of 91,000, producing slightly smaller domains.
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| [[Image:SBSstructure.svg|thumb|right|SBS block copolymer schematic microstructure]]
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| Microphase separation is a situation similar to that of [[oil]] and [[water]]. Oil and water are immiscible - they phase separate. Due to incompatibility between the blocks, block copolymers undergo a similar phase separation. Because the blocks are covalently bonded to each other, they cannot demix macroscopically as water and oil. In "microphase separation" the blocks form [[nanometer]]-sized structures. Depending on the relative lengths of each block, several morphologies can be obtained. In diblock copolymers, sufficiently different block lengths lead to nanometer-sized spheres of one block in a matrix of the second (for example [[Polymethyl methacrylate|PMMA]] in polystyrene). Using less different block lengths, a "hexagonally packed cylinder" geometry can be obtained. Blocks of similar length form layers (often called [[lamella (materials)|lamellae]] in the technical literature). Between the cylindrical and lamellar phase is the [[gyroid]] phase. The nanoscale structures created from block copolymers could potentially be used for creating devices for use in computer [[memory]], nanoscale-templating and nanoscale separations.<ref>Oz Gazit, Rafail Khalfin, Yachin Cohen and Rina Tannenbaum "Self-assembled diblock copolymer "nanoreactors" as catalysts for metal nanoparticle synthesis" Journal of Physical Chemistry C 113 (2009) 576. http://dx.doi.org/10.1021/jp807668h</ref>
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| Polymer scientists use [[thermodynamics]] to describe how the different blocks interact. The product of the degree of polymerization, ''n'', and the Flory-Huggins [[interaction parameter]], <math>\chi</math>, gives an indication of how incompatible the two blocks are and whether or not they will microphase separate. For example, a diblock copolymer of symmetric composition will microphase separate if the product <math>\chi N</math> is greater than 10.5. If <math>\chi N</math> is less than 10.5, the blocks will mix and microphase separation is not observed. The incompatibility between the blocks also affects the solution behavior of these copolymers and their adsorption behavior on various surfaces.<ref>Eli Hershkovitz, Allen Tannenbaum and Rina Tannenbaum, "Adsorption of block co-polymers from selective solvents on curved surfaces" Macromolecules 41 (2008) 3190. http://dx.doi.org/10.1021/ma702706p</ref>
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| ==Copolymer equation==
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| An alternating copolymer has the formula: -A-B-A-B-A-B-A-B-A-B-, or -(-A-B-)<sub>n</sub>-. The molar ratios of the monomer in the polymer is close to one, which happens when the reactivity ratios r<sub>1</sub> & r<sub>2</sub> are close to zero, as given by the [[Mayo–Lewis equation]] also called the '''copolymerization equation''':<ref>''Copolymerization. I. A Basis for Comparing the Behavior of Monomers in Copolymerization; The Copolymerization of Styrene and Methyl Methacrylate'' [[Frank R. Mayo]] and [[Frederick M. Lewis]] [[J. Am. Chem. Soc.]]; '''1944'''; 66(9) pp 1594 - 1601; {{DOI|10.1021/ja01237a052}}</ref>
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| <math>\frac {d\left [M_1 \right]}{d\left [M_2\right]}=\frac{\left [M_1\right]\left (r_1\left[M_1\right]+\left [M_2\right]\right)}{\left [M_2\right]\left (\left [M_1\right]+r_2\left [M_2\right]\right)}</math>
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| where r<sub>1</sub> = k<sub>11</sub>/k<sub>12</sub> & r<sub>2</sub> = k<sub>22</sub>/k<sub>21</sub>
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| ==Copolymer engineering==
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| Copolymerization is used to modify the properties of manufactured plastics to meet specific needs, for example to reduce crystallinity, modify [[glass transition temperature]] or to improve solubility. It is a way of improving mechanical properties, in a technique known as [[rubber toughening]]. Elastomeric phases within a rigid matrix act as crack arrestors, and so increase the energy absorption when the material is impacted for example. [[Acrylonitrile butadiene styrene]] is a common example.
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| ==See also==
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| {{commons category|Copolymers}}
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| * [[Polymer#Monomer_arrangement_in_copolymers|Copolymers section of Polymer article]]
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| * [[Thermoplastic elastomer]]
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| * [[Tholin]]
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| ==References==
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| {{reflist|2}}
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| ==External links==
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| *[http://www.chem.rochester.edu/~chem421/copoly.htm Introduction to Polymer Chemistry]
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| [[Category:Polymer chemistry]]
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| [[pl:Kopolimeryzacja]]
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| [[tr:Kopolimer]]
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Rudy Lafrance is what people contact him when his full name is used by individuals but he doesn't like Virginia is where my property is but I have to proceed for my family I'm a credit authoriser as well as the pay continues to be really fulfilling I cannot make it my occupation actually although what I really enjoy doing is shows
neighborhood pharmacy