ISSN:
1432-1017
Keywords:
Key words Diacetylenic lipids
;
Polymerization
;
Microfluorescence
;
Filmbalance
;
AFM
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Physics
Notes:
Abstract Molecular films from polymeric materials play an important role in basic research as well as in technology. We have synthesized the double chain diacetylenic ammonium lipid N-bis-(10, 12-pentacosadiinoyl)-oxy-ethyl)-N-methyl-amine (ONCO). We have characterized monomolecular films at the air/water interface by means of microfluorescence filmbalance techniques and by atomic force microscopy (AFM). ONCO forms stable monomolecular films that exhibit a fluid-solid phase transition with a transition enthalpy of 90 kJ/mol at 10 °C and neutral pH. The coexistence pressure was found to decrease with decreasing protonation, which is in contrast to the commonly found Coulomb mechanism. A change in the chain packing due to a different nitrogen bond angle is discussed as a possible mechanism. This model is cor-roborated by the finding that crystals at high and at low pH differ in their polymerization properties as measured by microfluorescence.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s002490050080
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