scholarly journals Critical Solutal Marangoni Number Correlation for Short-Scale Convective Instabilities in Drying Poly(vinyl acetate)-Methanol Thin Films

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2955
Author(s):  
Max Tönsmann ◽  
Philip Scharfer ◽  
Wilhelm Schabel
Keyword(s):  
Thin Films ◽  
Vinyl Acetate ◽  
Process Design ◽  
Self Assembly ◽  
Marangoni Number ◽  
Drying Process ◽  
Short Scale ◽  
Convective Instabilities ◽  
Schmidt Numbers ◽  
Dry Film

A new empiric correlation for the critical solutal Marangoni number as function of the Péclet and Schmidt numbers is proposed. It is based on previously published experimental flow field data in drying poly(vinyl acetate)-methanol films with an initial thickness in the range of – and an initial solvent load of to , as well as newly derived concentration profile measurements and 1D drying simulations. The analysis accounts for realistic transient material properties and describes the occurrence of short-scale convective Marangoni (in)stabilities during the entire drying process with an accuracy of 9%. In addition, the proposed correlation qualitatively follows trends known from theory. As convective Marangoni instabilities in drying polymer films may induce surface deformations, which persist in the dry film, the correlation may facilitate future process design for either thin films with uniform thickness or deliberate self-assembly.

scholarly journals Transient Three-Dimensional Flow Field Measurements by Means of 3D µPTV in Drying Poly(Vinyl Acetate)-Methanol Thin Films Subject to Short-Scale Marangoni Instabilities

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1223
Author(s):  
Max Tönsmann ◽  
Philip Scharfer ◽  
Wilhelm Schabel
Keyword(s):  
Flow Field ◽  
Vinyl Acetate ◽  
Three Dimensional ◽  
Field Measurements ◽  
Initial Assessment ◽  
Ambient Conditions ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Short Scale ◽  
Dry Film

Convective Marangoni instabilities in drying polymer films may induce surface deformations, which persist in the dry film, deteriorating product performance. While theoretic stability analyses are abundantly available, experimental data are scarce. We report transient three-dimensional flow field measurements in thin poly(vinyl acetate)-methanol films, drying under ambient conditions with several films exhibiting short-scale Marangoni convection cells. An initial assessment of the upper limit of thermal and solutal Marangoni numbers reveals that the solutal effect is likely to be the dominant cause for the observed instabilities.

Video real-time imaging of artificial membranes during freeze-drying by cryo-electron microscopy

1988 ◽  
Vol 46 ◽  
pp. 16-17
Author(s):  
Alan S. Rudolph ◽  
Ronald R. Price
Keyword(s):  
Real Time ◽  
Self Assembly ◽  
Freeze Drying ◽  
Video Capture ◽  
Drying Process ◽  
Artificial Membranes ◽  
The Past ◽  
Cryo Electron Microscopy ◽  
Spherical Structures ◽  
Capture Techniques

We have employed cryoelectron microscopy to visualize events that occur during the freeze-drying of artificial membranes by employing real time video capture techniques. Artificial membranes or liposomes which are spherical structures within internal aqueous space are stabilized by water which provides the driving force for spontaneous self-assembly of these structures. Previous assays of damage to these structures which are induced by freeze drying reveal that the two principal deleterious events that occur are 1) fusion of liposomes and 2) leakage of contents trapped within the liposome [1]. In the past the only way to access these events was to examine the liposomes following the dehydration event. This technique allows the event to be monitored in real time as the liposomes destabilize and as water is sublimed at cryo temperatures in the vacuum of the microscope. The method by which liposomes are compromised by freeze-drying are largely unknown. This technique has shown that cryo-protectants such as glycerol and carbohydrates are able to maintain liposomal structure throughout the drying process.

Nanoscratch-Directed Self-Assembly of Block Copolymer Thin Films

2021 ◽  
Vol 13 (4) ◽  
pp. 5772-5781
Author(s):  
Dong Hyup Kim ◽  
Ahram Suh ◽  
Geonhyeong Park ◽  
Dong Ki Yoon ◽  
So Youn Kim
Keyword(s):  
Thin Films ◽  
Block Copolymer ◽  
Self Assembly

nnEngineering coumarin-BODIPY thin-films and molecular crystals: tailoring supramolecular self-assembly for organic electronic applications

2021 ◽  
pp. 130437
Author(s):  
Javier Ordóñez-Hernández ◽  
Rafael Arcos-Ramos ◽  
Violeta Alvarez-Venicio ◽  
Vladimir A. Basiuk ◽  
Oscar González-Antonio ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
Molecular Crystals ◽  
Organic Electronic

scholarly journals Strain-Relief Patterns and Kagome Lattice in Self-Assembled C60 Thin Films Grown on Cd(0001)

2021 ◽  
Vol 22 (13) ◽  
pp. 6880
Author(s):  
Zilong Wang ◽  
Minlong Tao ◽  
Daxiao Yang ◽  
Zuo Li ◽  
Mingxia Shi ◽  
...  
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Kagome Lattice ◽  
Tunneling Microscopy ◽  
Kagomé Lattice ◽  
Temperature Scanning ◽  
C60 Films

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.

Different Adsorption States between Thiophene and α-Bithiophene Thin Films Prepared by Self-Assembly Method

2003 ◽  
Vol 42 (Part 2, No. 7B) ◽  
pp. L852-L855 ◽  
Author(s):  
Eisuke Ito ◽  
Jaegeun Noh ◽  
Masahiko Hara
Keyword(s):  
Thin Films ◽  
Self Assembly ◽  
Assembly Method

High-Fidelity Self-Assembly of Crystalline and Parallel-Oriented Organic Thin Films by π–π Stacking from a Metal Surface

Langmuir ◽  
2014 ◽  
Vol 30 (33) ◽  
pp. 10050-10056 ◽  
Author(s):  
Daniel Skomski ◽  
Junyong Jo ◽  
Christopher D. Tempas ◽  
Seyong Kim ◽  
Dongwhan Lee ◽  
...  
Keyword(s):  
Thin Films ◽  
Metal Surface ◽  
Self Assembly ◽  
Organic Thin Films ◽  
High Fidelity ◽  
Π Stacking

Impact of alkyl side chains at self-assembly, electronic structure and charge arrangement in sexithiophene thin films

2011 ◽  
Vol 12 (6) ◽  
pp. 903-910 ◽  
Author(s):  
Steffen Duhm ◽  
Qian Xin ◽  
Norbert Koch ◽  
Nobuo Ueno ◽  
Satoshi Kera
Keyword(s):  
Thin Films ◽  
Electronic Structure ◽  
Self Assembly ◽  
Side Chains ◽  
Alkyl Side Chains

Controlling nanomaterial synthesis, chemical reactions and self assembly in dynamic thin films

2014 ◽  
Vol 43 (5) ◽  
pp. 1387-1399 ◽  
Author(s):  
Xianjue Chen ◽  
Nicole M. Smith ◽  
K. Swaminathan Iyer ◽  
Colin L. Raston
Keyword(s):  
Thin Films ◽  
Chemical Reactions ◽  
Self Assembly ◽  
Nanomaterial Synthesis
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