Oligomers


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Related to Oligomers: Fibrils

Oligomers

 

members of homologous series occupying the region between monomers and polymers in terms of molecular size. The upper limit for the molecular weight of oligomers depends on their chemical nature and corresponds to the onset of high-elastic deformations, induced high elasticity, and other properties characteristic of macromolecular substances. Polar oligomers cover a wider range of molecular weights than do nonpolar oligomers (up to ∼ 1.5 × 104, as opposed to ∼ 5 × 103).

Most of the methods used in oligomer synthesis are based on macromolecule growth termination reactions in processes of polymerization and polycondensation. Oligomers are also obtained by degradation of macromolecular polymers and by stepwise synthesis, with the isolation of reaction products at each stage of the process; the latter method yields monodisperse oligomers.

Among the many reactive oligomers, the most important are polyester resins, epoxy resins, phenol-aldehyde resins, and alkyd resins, which have become widely used in the manufacture of laminated plastics, foam plastics, varnishes, adhesives, and sealing compounds. Oligoolefins are used as motor fuels and lubricants, in waterproofing treatment of paper, and in the preparation of polishing pastes (synthetic wax). Fluorine-substituted ethylene oligomers serve as high-boiling oils, heat-transfer agents, and fluids for hydraulic drives. Oligomers derived from an olefin oxide base are widely used as surface-active agents.

Oligomers play a relatively important role in nature. Examples are oxytocin (nonapeptide) and antibiotics (cyclooligopep-tides).

References in periodicals archive ?
INEOS Oligomers (http://www.ineosoligomers.com) produces a comprehensive range of specialty and intermediate chemicals including Linear Alpha Olefins, Poly Alpha Olefins, Polybutenes and Specialty Oligomers.
The results also indicated that synthetic alpha sheets could form the basis of therapeutics to clear toxic oligomers in people, according to corresponding author Valerie Daggett.
We have classified the oligomers in two types: those who have the strongly acceptor chromophore (acid 2-cyanoacrylic) (Mol i A) (Figure 2-a), and those who do not possess that chromophore (Mol i S) (figure 2-b).
Numerous studies on the effect of the chemical structure and properties of epoxy polymers show that changing the initial oligomers nature, hardeners, and their ratio can affect the structure and physicomechanical properties of epoxy polymers and materials based on them.
During depolymerization, hydronium ions from the catalyst enabled the cleavage of longer-chain cellooligomers to produce cello-oligiomers of shorter chain length while cello-oligomers of low DPw formed water-soluble oligomers.
In the present paper, we investigated the influence of host-associated proteins, A[[beta].sub.1-42] oligomers of various structures and pathogen-derived proteins, viral oligomeric proteins, on macrophage phenotype.
The theory applies to proteins, named oligomers, having several sub-units, named protomers.
Preparation of A-[beta]1-42 Oligomers. Amyloid [beta]-peptide (1-42) (human) was purchased from TOCRIS (Tocris-Bioscience, Ellisville, MO, USA).
Liu and Bhardwaj developed a material withstanding multiple steam sterilization events using polyester, polysulfone blends with epoxy-functional styrene-acrylate oligomers. The oligomer is essential for sterilization stability.
In our initial screening, we used difunctional urethane acrylate oligomers (UA) to mimic the softer polyol regions in the traditional two-part systems and trifunctional acrylate crosslinkers (M) for the harder isocyanate regions.