Selective Adsorption From Polymer Mixtures on Solid Surfaces

Abstract

Selective adsorption from binary polymer mixtures on a crystalline surface is studied in terms of the lattice gas model in conjunction with the results of the association theory. An interplay of the selectivity and the surface induced segregation is shown to result in a variety of competing factors which dominate the adsorption process. The role of the bead diameter, chain length and the surface activity in the preferential adsorption of one component is analyzed. A variation of the selectivity coefficient with the density and composition is also discussed.

Surface ordering in thin films of liquid‐crystalline polymers containing fluorinated and protonated segments: Neutron‐reflectometry study

“…The polymer under consideration consists of short fluorinated and protonated segments. Fluorinated segments are significantly more hydrophobic than hydrogenated chains, resulting in internal segregation 4, 6–8, 28–36. This partition is strong enough to drive liquid crystallinity in semifluorinated alkanes.…”

“…This study addresses the structure of thin films of a polymeric liquid crystal that consists of short alternating methylstilbene units and fluorinated cyclobutane segments. When polymers and liquid crystals are cast into thin films, the interfacial interactions become significant, determining the structure of the film 1–10. Among the most notable effects is surface‐induced segregation, enhancing ordering.…”

“…In the polymer under consideration, the interfacial structure is affected by all of the aforementioned parameters. Extensive experimental1–10 and theoretical studies11–19 address surface segregation of polymers, blends, and diblock copolymers. Theoretical studies11–14 of binary polymer blends have indicated that surface segregation is mainly driven by the difference of surface energies of the polymers.…”

“…The differences in the surface energies results from differences in their chemical composition and are strongly affected by minor differences in their stereochemical configuration. Polymers with lower surface energy tend to segregate to the air interface 4, 6–10. The sensitivity to small chemical variations is demonstrated by the segregation observed in blends of protonated and deuterated polystyrene 9, 10.…”

“…Introducing short fluorinated blocks into different alkanes and polymers results in a strong segregation between the protonated and fluorinated parts. Generally, the fluorinated parts with low surface energy are driven to the air surface 4, 6–8, 28–36. The surface tension decreases in the order of CH 2 (36 dyn/cm) > CH 3 (30 dyn/cm) > CF 2 (23 dyn/cm) > CF 3 (15 dyn/cm) 37.…”