page_title: Captodative effect
section_title: Polymer science application
hierarchical_section_title: Captodative effect / Polymer science application
caption_attribution_description: English: This image breaks down the possibly solvent affinity effects based on the different substituents of the monomer
context_page_description: The captodative effect is the stabilization of radicals by a synergistic effect of an electron-withdrawing substituent and an electron-donating substituent. The name originates as the electron-withdrawing group is sometimes called the "captor" group, whilst the electron-donating group is the "dative" substituent. Olefins with this substituent pattern are sometime described as captodative. Radical reactions play an integral role in several chemical reactions and are also important to the field of polymer science.
  When EDGs and EWGs are near the radical center, the stability of the radical center increases. The substituents can kinetically stabilize radical centers by preventing molecules and other radical centers from reacting with the center. The substituents thermodynamically stabilize the center by delocalizing the radical ion via resonance. These stabilization mechanisms lead to an enhanced rate for free-radical reactions. In the figure at right, the radical is delocalized between the captor nitrile, and the dative secondary amine, thus stabilizing the radical center.
context_section_description: Free-radical polymerization, where radicals are the chain carriers in the propagation of the process, accounted for 40 billion of the 110 billion pounds of polymers produced in the United States in 2001. Captodative olefins have a specific advantage of being responsive to solvent effects without the effect of destabilizing the radical. They have also shown to undergo their radical transformation spontaneously which allows them to be useful in polymerization mechanism elucidation and better understood through NMR Studies. Furthermore, captodative ethanes are initiators with unique properties giving higher molecular weight distribution and forming block copolymers through the known radical mechanisms. The polymers obtained from captodatively substituted starting materials exhibit "desirable" properties such as optical activity, differences in polarity, solvent affinity, thermal and mechanical stabilities.
  Polymers with polar substituents are known to have interesting applications including within electrical and optical materials.
  These polymers are typically transparent.
  The Tdi (initial decomposition) of these polymers are relatively low compared to their analogues, but have relatively higher Tdm (maximum rate of weight change temperatures). Meaning although they will start to melt quicker, they will take longer to fully change phases.
  Polymers with large captodative stabilizations starting materials can quickly “unzip” to their starting monomer upon heating.
  Bifunctional polymers, with two different functional groups at every monomer unit, are commonly formed from the captodative monomers.
  Dative groups substantially alter the solubility through Hydrogen bonding in specific bifunctional polymers( see figure above). However no clear correlation has been developed at this time, since not all combinations of substituents and solubilities have been investigated.
  Captodative polymer is highly functional in chelates with certain metals.
caption: Substituents on the monomer can affect solvent affinities
exif: {}