Monolayer films of PS-b-PEO diblock copolymers at the air/water- and an oil/water-interface |
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Authors: | G Rother G H Findenegg |
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Institution: | I. N. Stranski-Institut für Physikalische und Theoretische Chemie Technische Universit?t Berlin Stra?e des 17. Juni 112 10623 Berlin Germany, DE
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Abstract: | Amphiphilic diblock copolymers consisting of a hydrophobic polystyrene block (PS) and a hydrophilic poly(ethylene oxide)
block (PEO) with block sizes of 1000 or 3000 g/mol for both blocks were studied at the air/water and toluene/water interface.
Measurements of the film pressure π of spread monolayers at the water surface reveal two limiting regimes of the π−a
m isotherms, in which the mean molecular area a
m is determined either by the size of the hydrophilic or the hydrophobic blocks of the PS-PEO molecules. The interfacial activity
of the block copolymers at the toluene/water interface was studied by measuring the interfacial tension σ over a wide range
of concentrations. Pronounced differences in the temperature dependence of the interfacial tension were observed, depending
mostly on the block length of the hydrophilic PEO block. From the temperature dependence of σ it is inferred that for the
block copolymers with the PEO block size of 3000 g/mol the phase inversion temperature (PIT) is well above 60 °C while for
those with a PEO block size of 1000 g/mol the PIT is below or near 25 °C in the toluene/water system.
Received: 5 February 1998 Accepted: 16 February 1998 |
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Keywords: | Adsorption at liquid interfaces block copolymers film pressure interfacial tension polymer surfactants |
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