Polymer Termination
Polymer Termination - Related Videos
01:44
Termination of Translation
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2020
The large ribosomal subunit has several important structures essential to translation. These include the peptidyl transferase center (PTC) - which is the site where the peptide bond is formed - and a large, internal, water-filled tube through which the nascent polypeptide moves. This latter structure is called the Peptide Exit Tunnel, and it begins at the PTC and spans the body of the large ribosomal subunit. During translation, as the nascent polypeptide chain is synthesized, it passes through...
02:34
Polymers
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2020
The word polymer is derived from the Greek words “poly” which means “many” and “mer” which means “parts”. Polymers are long chains of molecules composed of repeating units of smaller molecules, known as monomers. They either occur naturally, such as DNA and proteins, or can be constructed synthetically, like plastics. They have varied structural characteristics, such as linear chains, branched chains, or complex networks, that contribute to the properties that they exhibit. Additionally,...
08:44
Tension Tests of Polymers
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2023
Source: Roberto Leon, Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA Polymeric materials are widely used in civil structures, with uses ranging from very soft sealants to more rigid pipes in water and wastewater systems. The most basic definition of a polymer is a molecular structure with repeating subunits. The term polymer comes from Greek, where "poly" means many, and "-mer" means basic unit. Monomers, or single mers, are the specific repeating units. With...
15:16
Loading Drosophila Nerve Terminals with Calcium Indicators
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Cited by 17 •
2007
Calcium is a ubiquitous messenger in the nervous system, essential for triggering neurotransmitter release and changes in synaptic strength. Here we demonstrate a technique for loading Ca2+-indicators into Drosophila nerve terminals. We also demonstrate fabrication of the required apparatus and emphasize points critical for the technique's success.
08:12
Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers
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2022
Here, we describe protocols for the preparation of trans-cyclobutane fused cyclooctenes (tCBCO), their polymerization to prepare depolymerizable olefinic polymers, and the depolymerization of these polymers under mild conditions. Additionally, protocols for the preparation of depolymerizable networks and compression molding of rigid linear plastics based on this system are described.
FAQs
Two principal radical pathways produce different molecular outcomes. In combination, two growing radicals form one larger polymer molecule, so the resulting chain has a combined origin and a corresponding final end-group arrangement. In disproportionation, hydrogen transfer instead creates two nonradical chains with different end-group structures. This distinction matters when interpreting polymer architecture and end-group functionality.
Hydrogen transfer changes the chemical identity of both chains produced during disproportionation. Rather than joining two growing radicals into one molecule, the transfer yields two nonradical chains with different end-group structures. Those end groups provide information about how the reaction stopped and can influence how chemists interpret the final polymer’s composition and functionality.
Termination control helps regulate several characteristics of the final material, including molecular weight, molecular-weight distribution, branching, and end-group functionality. Because these features influence how a polymer is designed and characterized, selecting or managing the termination behavior provides a way to connect chain-growth reaction outcomes with the requirements of coatings, plastics, adhesives, and advanced materials.
Deliberate quenching or reaction with an inhibitor provides an additional route for stopping reactive chain growth. The intervention deactivates reactive polymer chain ends rather than allowing them to continue adding monomer. Chemists can therefore use this approach when they need to halt the process intentionally and establish final end groups for subsequent polymer characterization or material design.
Final end groups record how reactive chain growth ended. Combination, disproportionation, quenching, and inhibitor reactions can produce different end-group structures, making those structures useful for interpreting the termination pathway. Examining end-group functionality also helps connect molecular-level reaction behavior with the measured or intended characteristics of a polymer material.
Controlled termination is relevant wherever polymer structure must match a practical material function. In chemistry, it supports the design and characterization of polymers used in coatings, plastics, adhesives, and advanced materials. Its importance comes from the ability to influence molecular weight, distribution, branching, and end-group functionality, which are central descriptors of the resulting polymer.