scholarly journals Photoswitching the mechanical properties in Langmuir layers of semifluorinated alkyl-azobenzenes at the air–water interface

2015 ◽  
Vol 17 (43) ◽  
pp. 28844-28852 ◽  
Author(s):  
Antigoni Theodoratou ◽  
Ulrich Jonas ◽  
Benoit Loppinet ◽  
Thomas Geue ◽  
René Stangenberg ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Light Stimulus ◽  
Fluid Interfaces ◽  
Water Interface ◽  
Structure And Dynamics ◽  
Air Water Interface

Manipulation of the structure and dynamics of semifluorinated alkyl-azobenzene layers at the air–water interface by an external light stimulus suggests ways of tailoring responsive fluid interfaces.

scholarly journals The interfacial structure and Young's modulus of peptide films having switchable mechanical properties

2007 ◽  
Vol 5 (18) ◽  
pp. 47-54 ◽  
Author(s):  
A.P.J Middelberg ◽  
L He ◽  
A.F Dexter ◽  
H.-H Shen ◽  
S.A Holt ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Self Assembly ◽  
Molecular Design ◽  
Foam Stability ◽  
Young's Modulus ◽  
Interfacial Structure ◽  
Water Interface ◽  
Air Water Interface ◽  
Peptide Dissociation

We report the structure and Young's modulus of switchable films formed by peptide self-assembly at the air–water interface. Peptide surfactant AM1 forms an interfacial film that can be switched, reversibly, from a high- to low-elasticity state, with rapid loss of emulsion and foam stability. Using neutron reflectometry, we find that the AM1 film comprises a thin (approx. 15 Å) layer of ordered peptide in both states, confirming that it is possible to drastically alter the mechanical properties of an interfacial ensemble without significantly altering its concentration or macromolecular organization. We also report the first experimentally determined Young's modulus of a peptide film self-assembled at the air–water interface ( E =80 MPa for AM1, switching to E <20 MPa). These findings suggest a fundamental link between E and the macroscopic stability of peptide-containing foam. Finally, we report studies of a designed peptide surfactant, Lac21E, which we find forms a stronger switchable film than AM1 ( E =335 MPa switching to E <4 MPa). In contrast to AM1, Lac21E switching is caused by peptide dissociation from the interface (i.e. by self-disassembly). This research confirms that small changes in molecular design can lead to similar macroscopic behaviour via surprisingly different mechanisms.

Linear and nonlinear microrheology of lysozyme layers forming at the air–water interface

Soft Matter ◽  
2014 ◽  
Vol 10 (36) ◽  
pp. 7051-7060 ◽  
Author(s):  
Daniel B. Allan ◽  
Daniel M. Firester ◽  
Victor P. Allard ◽  
Daniel H. Reich ◽  
Kathleen J. Stebe ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Interface ◽  
Nonlinear Mechanical ◽  
Air Water Interface ◽  
Linear And Nonlinear

Microrheology tracks the evolution in the linear and nonlinear mechanical properties of layers of the protein lysozyme adsorbing at the air–water interface as the layers undergo a viscoelastic transition.

scholarly journals Methylguanidinium at the Air/Water Interface: A Simulation Study with the Drude Polarizable Force Field

2020 ◽  
Author(s):  
Jian Zhu ◽  
Jing Huang
Keyword(s):  
Force Field ◽  
Model Compound ◽  
Side Chain ◽  
Water Interface ◽  
Polarizable Force Field ◽  
Polarization Effects ◽  
Structure And Dynamics ◽  
Arginine Side Chain ◽  
Air Water Interface ◽  
Dynamics Simulations

<div>Methylguanidinium is an important molecular ion which also serves as the model compound for arginine side chain. We studied the structure and dynamics of methylguanidium ion at the air/water interface by molecular dynamics simulations employing the Drude polarizable force field. We found out that methylguanidinium accumulate on the interface with a majority adopting tilted conformations. We also demonstrated that methylguanidinium and guanidinium ions have different preference towards the air/water interface. Our results illustrate the importance to explicitly include the electronic polarization effects in modeling interfacial properties.</div><div><br> </div>

Langmuir films and mechanical properties of polyethyleneglycol fatty acid esters at the air-water interface

2016 ◽  
Vol 498 ◽  
pp. 50-57 ◽  
Author(s):  
Stephanie Ortiz-Collazos ◽  
Yan M.H. Gonçalves ◽  
Bruno A.C. Horta ◽  
Paulo H.S. Picciani ◽  
Sonia R.W. Louro ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fatty Acid ◽  
Langmuir Films ◽  
Fatty Acid Esters ◽  
Water Interface ◽  
Air Water Interface ◽  
Acid Esters

scholarly journals Time-dependent vibrational sum-frequency generation spectroscopy of the air-water interface

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Deepak Ojha ◽  
Naveen Kumar Kaliannan ◽  
Thomas D. Kühne
Keyword(s):  
Sum Frequency Generation ◽  
Time Dependent ◽  
Water Molecules ◽  
Water Interface ◽  
Sum Frequency ◽  
Generation Spectrum ◽  
Structure And Dynamics ◽  
Sum Frequency Generation Spectroscopy ◽  
Air Water Interface ◽  
Frequency Generation

Abstract Vibrational sum-frequency generation spectroscopy is a powerful method to study the microscopic structure and dynamics of interfacial systems. Here we demonstrate a simple computational approach to calculate the time-dependent, frequency-resolved vibrational sum-frequency generation spectrum (TD-vSFG) of the air-water interface. Using this approach, we show that at the air-water interface, the transition of water molecules with bonded OH modes to free OH modes occurs at a time scale of $$\sim$$ ~ 3 ps, whereas water molecules with free OH modes rapidly make a transition to a hydrogen-bonded state within $$\sim$$ ~ 2 ps. Furthermore, we also elucidate the origin of the observed differential dynamics based on the time-dependent evolution of water molecules in the different local solvent environments.

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