Technology & Engineering
Oligomer
An oligomer is a molecule composed of a small number of repeating units, typically between 3 and 20. In the field of technology and engineering, oligomers are important in the development of materials such as plastics, adhesives, and coatings. They are used to modify the properties of these materials, such as strength, flexibility, and durability.
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3 Key excerpts on "Oligomer"
eBook - PDFElements of Polymer Science & Engineering
An Introductory Text and Reference for Engineers and Chemists
- Alfred Rudin(Author)
- 1998(Publication Date)
- Academic Press(Publisher)
2 1 Introductory Concepts and Definitions reader may have learned in other branches of science. This should not be cause for alarm, since all the more important definitions that follow are clear in the contexts in which they are normally used. Ll.l Polymer Polymer means many parts and designates a large molecule made up of smaller repeating units. Thus the structure of polystyrene can be written H H H H t i l l '^ CH2-C-CH2-C- CH2-C-CH2-C--(o) (S) (o) (^ M Polymers generally have molecular weights greater than about 5000 but no firm lower limit need be defined since the meaning of the word is nearly always clear from its use. The word macromolecule is a synonym for polymer. 1.1.2 Monomer A monomer is a molecule that combines with other molecules of the same or different type to form a polymer. Acrylonitrile, CH2=CHCN, is the monomer for polyacrylonitrile: H H t I ^ C H ^ -C -C H o -C -C H o -I I CN CN 1-2 which is the basic constituent of acrylic fibers. 1.1.3 Oligomer An Oligomer is a low-molecular-weight polymer. It contains at least two monomer units. Hexatriacontane (n-CH3—(CH2)29—CH3) is an Oligomer of polyethylene A^^ CH2CH2CH2CH2CH2CH2CH2CH2CH2 '^l 1-3 H 1 1 c-1 CN CH2-H 1 1 -C -1 CN 1.1 Some Definitions 3 Generally speaking, a species will be called polymeric if articles made from it have significant mechanical strength and Oligomeric if such articles are not strong enough to be practically useful. The distinction between the sizes of Oligomers and the corresponding polymers is left vague, however, because there is no sharp transition in most properties of interest. The terms used above stem from Greek roots: mews (part), poly (many), oligo (few), and mono (one). 1 . 1.4 Repeating Unit The repeating unit of a linear polymer (which is defined below) is a portion of the macromolecule such that the complete polymer (except for the ends) might be produced by linking a sufficiently large number of these units through bonds between specified atoms.
eBook - PDFThe Elements of Polymer Science and Engineering
An Introductory Text for Engineers and Chemists
- Alfred Rudin(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
This should not be cause for alarm, since all the more important definitions that follow are clear in the contexts in which they are normally used. 1.1.1 Polymer This word means many parts and designates a large molecule made up of smaller repeating units. Thus the structure of polystyrene can be written Η Η Η Η I I I ι ~ CH 2 —C—CH 2 — C—CH 2 —C—CH 2 — C ~ 1-1 Polymers generally have molecular weights greater than about 5000 but no firm lower limit need be defined since the meaning of the word is nearly always clear from its use. The word macromolecule is a synonym for polymer. 1.1.2 Monomer A monomer is a molecule which combines with other molecules of the same or different type to form a polymer. Acrylonitrile, C H 2 = C H C N , is the monomer for poly acrylonitrile: Η Η Η Η I I I I ~ CH 2 —C — CH 2 — C — CH 2 — C —CH 2 — C ~ I I I I CN CN CN CN 1-2 which is the basic constituent of acrylic fibers. 1.1 Some Definitions 3 1.1.3 Oligomer An Oligomer is a low-molecular-weight polymer. It will contain at least two monomer units. Hexatriacontane (n-CH 3 —(CH 2 )29-CH 3 ) is an Oligomer of polyethylene — C H 2 C H 2 C H 2 C H 2 C H 2 C H 2 C H 2 C H 2 C H 2 — 1 -3 Generally speaking, a species will be called polymeric if articles made from it have significant mechanical strength and Oligomeric if such articles are not strong enough to be practically useful. The distinction between the sizes of Oligomers and the corresponding polymers is left vague, how-ever, because there is no sharp transition in most properties of interest. The terms used above stem from the Greek roots: meros (part), poly (many), oligo (few), and mono (one). 1.1.4 Repeating Unit The repeating unit of a linear polymer (which is defined below) is a portion of the macromolecule such that the complete polymer (except for the ends) might be produced by linking together a sufficiently large number of these units through bonds between specified atoms.
eBook - PDF- Klaus M¿llen, G. Wegner, G. Wegner, Klaus Müllen, G. Wegner, Klaus Müllen(Authors)
- 2008(Publication Date)
- Wiley-VCH(Publisher)
Researchers with different backgrounds are involved with the study of Oligomers: polymer scientists have prepared Oligomers as models for polymers, while organic chemists have made Oligomers as higher homologs of monomers - with the under- standing that 'real' compounds are monodisperse. This book is concerned with conjugated Oligomers and their role as electronic materials. Since Oligomers have long been a topic of polymer research [ 1, 4, the introduction will first outline some general aspects of the chemistry and physics of Oligomers, then describe the role of 7r-conjugation in Oligomers and finally consider the function of Oligomers in materials science, for example, as active components of devices. 1. General Aspects of Oligomer Research The controlled synthesis of Oligomers with well-defined endgroups and chain lengths by a condensation mechanism requires a step-wise approach. Consider the reaction of terephthalic acid 1 with an alkanediol2 to yield Oligomers with the repeating unit 3. The first condensation step between the two bifunctional components requires one acid and one $coho1 function, respectively, to carry different protection groups, say P' and P-. What is important for further transformations of the result- ing monoester 4 is that the protecting groups can be cleaved separately and the next condensation be initiated at either end. While this Oligomer synthesis is conceptually straightforward, it becomes increasingly tedious for higher Oligomers. Not surpris- ingly, therefore, Oligomers are also made using a random approach, e.g., through the direct coupling of bifunctional starting compounds such as diols and diacids. While the stoichiometry of reactions can be varied to favor Oligomer formation,
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