ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Alkyl-perfluoroalkyl compounds are known to form a microphase-separated structure due to the thermodynamic immiscibility between the fluorinated and the protonated segments [1,2]. Many similarities between bulk and surface structures of such polymers were found in the past [2,3,4] which can be explained by both microphase separation in the bulk as well as surface segregation of the fluorinated parts. Basing on this concept, polymers with chemically different main chains were attached with alkylperfluoroalkyl side chains (particularly, oxydecylperfluorodecyl chains, -O-(CH〈sub〉2〈/sub〉) 〈sub〉10〈/sub〉-(CF 〈sub〉2〈/sub〉) 〈sub〉9〈/sub〉-CF 〈sub〉3〈/sub〉). Combined investigations by means oftemperature-dependent X-ray scattering, molecular modeling and DSC measurements were performed to characterize the bulk structure in dependence on the flexibility of the main chain as well as the density of side chains. The polymers under investigation show one or more phase transitions in the temperature range from room temperature to 300 °C which can be assigned as transitions between different smectic structures. These phases are characterized to have positive aswell as negative expansion coefficients, respectively, indicating changes of the tilt angle of the side chains and/or the degree of interdigitation. The polymer melts feature a high memory behavior evidenced by reversed imaging of the scattering patterns in the heating and cooling runs
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/07/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.443-444.223.pdf
Permalink