287694 Surface Segregation of Well-Defined Comb Polymers

Tuesday, October 30, 2012: 10:40 AM
Butler East (Westin )
Boxi Liu1, Roderic P. Quirk1, Mark D. Foster1, Renfeng Hu2 and David T. Wu3, (1)Department of Polymer Science, The University of Akron, Akron, OH, (2)Chemical Engineering Department, Colorado School Of Mines, Golden, CO, (3)Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO

Interfacial segregation phenomenon in polymer blends of different chain architectures may be employed to control interfacial properties. It has been theoretically predicted by Wu et al.1 that a long-chain, branched polymer blended with its linear analog will be preferentially segregated to the interfaces of the blend film. Among the long-chain branching architectures, comb polymers are promising candidates for achieving substantial surface segregation for tailoring surface properties, since their high degree of branching provides a significant driving force for surface segregation when chain ends prefer the surface. We prepared comb polystyrenes with well-defined architectural details by living anionic polymerization via the “grafting-through” approach. Neutron reflectivity (NR) and secondary ion mass spectrometry (SIMS) analyses reveal that the comb polymers that are still miscible with linear analogs in the bulk segregate so strongly to the surface that the surface concentration of combs is nearly 100 vol% under certain conditions. The level of surface segregation is affected by factors including comb architecture, bulk concentration, and chain end chemistry. Surprisingly, thermal annealing is not necessary to achieve strong surface segregation for these comb polymers. Wu’s linear response theory suggests that a modest surface attraction on the order of kT for chain ends is sufficient to generate surface composition profiles that match the experimentally measured surface composition and segregation length scale.

Acknowledgements:  NSF support (CBET 0730692 & 0731319) is gratefully acknowledged.

Reference:

1     Wu, D. T.; Fredrickson, G. H. Macromolecules 1996, 29, 7919-7930.


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