A reversibly switching block copolymer surface
We present linear (AB)(n)() multiblock copolymers that exhibit a thermally induced reversible alteration of the surface composition at a sharply defined transition temperature T(s) of 120-170 degrees C depending on the polymer structure. At temperatures below T(s) the surface consists of block A, a...
| Veröffentlicht in: | Langmuir : the ACS journal of surfaces and colloids. - 1991. - 21(2005), 23 vom: 08. Nov., Seite 10573-80 |
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| Format: | Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2005
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| Zugriff auf das übergeordnete Werk: | Langmuir : the ACS journal of surfaces and colloids |
| Schlagworte: | Journal Article |
| Zusammenfassung: | We present linear (AB)(n)() multiblock copolymers that exhibit a thermally induced reversible alteration of the surface composition at a sharply defined transition temperature T(s) of 120-170 degrees C depending on the polymer structure. At temperatures below T(s) the surface consists of block A, a 4,4'-methylenediphenyl diisocyanate (4,4'-MDI) type polyurea, whereas above T(s) the hydrophobic block B, a poly(ricinoleic acid hexanediol ester) dominates the surface composition. The ratio of surface concentrations c(A)/c(B) changes by a factor of at least 1000 within an analyzed depth of approximately 10 A. The full A-B surface transition is obtained within minutes. A mechanism is proposed where microphase crystallization of block A in the bulk effectively locks surface segregation of the hydrophobic block B, yielding an A-rich surface. The topology of the copolymers imposes sufficient restrictions for the lateral separation of the connected constituents such that surface segregation is largely reduced. Only above the transition temperature T(s) of microphase crystallization of block A can block B segregate to the surface, yielding a B-rich surface. Such a scheme of competing self-organizing processes in copolymers may potentially be used to reversibly switch surface properties such as adhesion and wetting in various applications |
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| Beschreibung: | Date Completed 04.05.2007 Date Revised 02.11.2005 published: Print Citation Status PubMed-not-MEDLINE |
| ISSN: | 0743-7463 |