Domain formation, polymerization induced

The authors surmised that the crosslinking polymerization of 14 resulted in the formation of only small polymers. They estimated an aggregation number, N < 10, for the domains of crosslinked 14 [43]. The careful analysis of the phase behavior of these lipids and the effect of polymerization at selected conditions coincided with the realization that polymerization of a lipid that is miscible with a second nonreactive lipid could cause phase separation of the lipids into enriched domains. This polymerization-induced lipid domain formation is considered more completely in the following section of this review. 

Fig. It. Structures of crosslinkable phosphatidylcholines which have been usefully employed for polymerization-induced domain formation left to right the compounds are bis-DenPCig,ig bis-SorbPC1717 and bis-AcrylPC1616, where the subscripts indicate the number of atoms in the fatty acid chain.

Armitage, B., Klekota, P.A., Oblinger, E., and O Brien, D.F. (1993) Enhancement of energy transfer on bilayer surfaces via polymerization-induced domain formation, J. Am. Chem. Soc., 115, 7920-7921. 

The information provided by the 31P-NMR spectra of DOPE/16 as a function of temperature and the extent of polymerization was critical to the characterization of the nature of the lipid structures responsible for the destabilization of the photolyzed DOPE/16 vesicles [73]. The progressive appearance of an isotropic NMR signal at the expense of the lamellar signal (Fig. 14) indicated that a lipid structure with isotropic symmetry was associated with the photo-induced leakiness of DOPE/16 vesicles. The enriched domains of PE facilitates the interaction and formation of intermediate lipid structures between bilayers, with the eventual development of an ILA(s) that connect the bilayers of an... 

The polymerization of propylene using complex 14 activated by MAO (Al Zr ratio=500, solvent toluene, 25 °C) yielded 80 g polymer-mol Zrl-hrl with a molecular weight Mw= 115,000 and polydispersity=2.4 [119]. The reaction was carried out in liquid propylene to avoid, as much as possible, the epimerization of the last inserted monomer unit and to allow rational design of the elastomeric polymer. The formation of elastomeric polypropylene is consistent with the proposed equilibrium between ds-octahedral cationic complexes with C2 symmetry inducing the formation of the isotactic domain, and tetrahedral complexes with C2v symmetry responsible for the formation of the atactic domain (Scheme 7). The narrow polydispersity of the polypropylene obtained supports the polymerization mechanism in which the single-site catalyst is responsible for the formation of the elastomeric polymer. 

Polymerization of surfactant within a bilayer membrane induced a formation of specific domain that concentrated cyanine and porphyrin molecules to enhance the energy transfer. The energy transfer efficiency increased up to 71% at a 100% polymerization, whereas the efficiency was 9% without polymerization. 

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