Crossover from semi-dilute to densely packed thin polymer films at the air-water interface and structure formation at thin film breakup

A series of poly(n-butyl acrylate) (PnBA, 5 to 32 kg mol-1) homopolymers and diblock copolymers with poly(ethylene glycol) (PEG, constant molecular weight of 0.3 kg mol-1) is synthesized for the purpose of the investigation of quasi-2D polymer films at the air-water interface. The presented compress...

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Bibliographic Details
Published in:Soft matter 2018, Vol.14 (23), p.4750-4761
Main Authors: Appel, Christian, Kraska, Martin, Rüttiger, Christian, Gallei, Markus, Stühn, Bernd
Format: Article
Language:English
Subjects:
Block copolymers
Breakup
Chemical synthesis
Compression
Copolymers
Dilution
Isotherms
Microscopy
Molecular chains
Molecular weight
Mud-water interfaces
Polyethylene glycol
Polymer films
Polymers
Thin films
Variation
X-ray scattering
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Summary:A series of poly(n-butyl acrylate) (PnBA, 5 to 32 kg mol-1) homopolymers and diblock copolymers with poly(ethylene glycol) (PEG, constant molecular weight of 0.3 kg mol-1) is synthesized for the purpose of the investigation of quasi-2D polymer films at the air-water interface. The presented compression isotherms show a transition from θ solvent behavior for PnBA homopolymers to good solvent conditions when the volume fraction of the PEG in the block copolymers is increased by decreasing the molecular weight of PnBA. A transition from a semi-dilute regime to a densely packed layer is observed in the pressure isotherms for all the polymers. In the densely packed films we found first evidence for thin film breakup of a thin polymer film directly at the air-water interface. Combination of results from Brewster-Angle-Microscopy and Surface X-ray scattering provide a consistent picture of the film breakup. Our results suggest a preferred length scale of 2.5 μm. This scenario is analogous to a spinodal mechanism driven by thermal fluctuations of the film height.
ISSN:1744-683X
1744-6848
DOI:10.1039/c8sm00629f