Stratification of polymer–colloid mixtures<i>via</i>fast nonequilibrium evaporation

Lee, Kyoungmun; Choi, Siyoung Q.

doi:10.1039/d0sm01504k

Cited by 8 publications

(8 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When dispensing a colloid-PEG droplet on a substrate at 80 °C, the resultant fast evaporation leads to a sharp increase in both the concentration of nanoparticles and PEG near the air–liquid interface. With the increasing concentration of components as well as the associated viscosity of the solution (Figure S9), a skin layer at the droplet surface forms. ,, The fast evaporation of the droplet also results in a surface capture effect. , Because of this effect, a rapidly descending air–liquid interface can kinetically capture nanoparticles near the droplet surface (Figure b). With more and more nanoparticles getting captured by the surface, nanoparticles pack into an equilateral triangular structure and then form an FCC lattice with its (111) plane oriented parallel to the droplet surface due to the attractive capillary force between nanoparticles (Figure c). ,,, To support this surface capture effect, the descending rate of the droplet air–liquid interface ( v in ) should be larger than the diffusion rate of the particles ( v p ) .…”

Section: Resultsmentioning

confidence: 99%

“…This is indicated by the blue center of the deposition, suggesting the formation of the (111) plane orientation of the FCC lattice in the skin phase. In addition, nanoparticles should be wettable by PEG (Figure e). , Otherwise, the polymer and nanoparticles would self-stratify to a polymer layer and a nanoparticle layer (Figure S11). Both the peak near 3650 cm –1 in the Fourier transform infrared spectra (FTIR) of the colloid-PEG mixture and the slightly increased diameter of colloidal nanoparticles indicate the good wettability of the PEG on nanoparticles (Figure f and Figure S12).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Heterogeneous Self-Assembly of a Single Type of Nanoparticle Modulated by Skin Formation

et al. 2023

ACS Nano

View full text Add to dashboard Cite

Self-assembly of colloidal nanoparticles has generated tremendous interest due to its widespread applications in structural colorations, sensors, and optoelectronics. Despite numerous strategies being developed to fabricate sophisticated structures, the heterogeneous self-assembly of a single type of nanoparticle in one step remains challenging. Here, facilitated by spatial confinement induced by a skin layer in a drying droplet, we achieve the heterogeneous self-assembly of a single type of nanoparticle by quickly evaporating a colloid-poly (ethylene glycol) (PEG) droplet. During the drying process, a skin layer forms at the droplet surface. The resultant spatial confinement assembles nanoparticles into face-centered-cubic (FCC) lattices with (111) and (100) plane orientations, generating binary bandgaps and two structural colors. The self-assembly of nanoparticles can be regulated by varying the PEG concentration so that FCC lattices with homo- or heterogeneous orientation planes can be prepared on demand. Besides, the approach is applicable for diverse droplet shapes, various substrates, and different nanoparticles. The one-pot general strategy breaks the requirements for multiple types of building blocks and predesigned substrates, extending the fundamental understanding underlying colloidal self-assembly.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Heterogeneous Self-Assembly of a Single Type of Nanoparticle Modulated by Skin Formation

et al. 2023

ACS Nano

View full text Add to dashboard Cite

show abstract

“…The study shows the stratification of the mixture may not rely on the drying rate. 35 According to the Pe = v ev H/D, the stratification of the coating is mainly related to the diffusion constant D under a constant evaporation rate. With the polymer concentration increasing under evaporation, the viscosity of the mixture near the liquid−air interface increases, .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The microstructure, or rather the distribution of nanoparticles and polymer binder in the coating, plays a vital role on the performance of SSC. The preceding works, including simulation, modeling, and experiment, show that the stratified structures of the polymer-on-top or particle-on-top can be realized by tailoring the nanoparticle/polymer interaction, hydrodynamic interactions, gyration radius or length of polymer, molecular weight of polymer, and evaporation rate, , as well as the sedimentation of aggregated particles or floating-up of lightweight particles (e.g., hollow glass spheres and aerogel particles). , Nevertheless, the implementation of these strategies puts forward high requirements for polymer-to-particle matching, processing conditions, and nanoparticle features. This demonstrates that there are still many challenges to overcome (e.g., construction and structural regulation of the hard colloidal-soft polymer composite SSC by a simple approach) before widespread industrial application of high-performance water-based composite SSC can be achieved.…”

Section: Introductionmentioning

confidence: 99%

Self-Stratifying Coating with Robust and Durable Superhydrophobic Underlayer Constructed by Amphiphilic Janus Nanoparticles

Yang

Liu

et al. 2023

Chem. Mater.

View full text Add to dashboard Cite

The multifunctional gradient self-stratifying coating (SSC) is attractive in many applications, but the robustness and durability of the functionalities still remains challenging. Here, a water-based SSC composed of amphiphilic Janus nanoparticles (JNPs) and binder latex is constructed by an extremely simple one-step drying method. The surface-partitioned “soft–hard” JNPs are specially designed and synthesized, in which the hard side of the JNPs (fluorosilane modified silica) imparts hydrophobicity and mechanical strength to the SSC, and the soft side contributes to the uniform dispersion of the hydrophobic JNPs in a water-based mixture and strong adhesion of JNPs to binder. Coatings with various microstructures and properties could be obtained simply by adjusting the binder solid content. Among them, the desirable SSC with a binder-rich upper layer and a JNPs-rich lower layer possesses a smooth surface and a superhydrophobic underlayer. The superhydrophobic underlayer of this SSC exhibits durable superhydrophobicity after 300 abrasion cycles and remarkable water repellency after heavy pull-off as well as good flexibility (film-forming). Our designs could provide new strategies for the development of low-cost and high-performance water-based SSC.

show abstract

“…Processing effects are well studied for other types of binary systems where the constituents have disparate sizes, such as colloid/colloid, polymer/colloid, and linear polymer/polymer systems. − These studies have shown that the ratio of the Péclet numbers of the constituents plays an important role in dictating surface enrichment in these blends. The Pe number describes the relative rates of solvent evaporation and solute diffusion: where η is the solvent viscosity, R h is the hydrodynamic radius of the particle, H is the initial film thickness, E is the rate of evaporation, k is the Boltzmann’s constant, and T is the temperature.…”

Section: Introductionmentioning

confidence: 99%

Impact of Processing Effects on Surface Segregation of Bottlebrush Polymer Additives

et al. 2022

View full text Add to dashboard Cite

The surface properties of polymeric materials govern interactions with the surroundings and are responsible for various application-relevant properties. Recent studies have shown that bottlebrush polymers can be used to modify the surface chemistry of the polymers because they spontaneously segregate to the interfaces when they are blended with the linear polymers, driven in large part by entropic effects that arise from the unique architecture of bottlebrush polymers. However, while prior work has largely focused on equilibrium segregation profiles, kinetic and processing effects can also drive bottlebrush additives to surfaces and interfaces. In solution-cast blends of polymers and colloids, vertical stratification is controlled by the relative Pećlet (Pe) numbers of the constituents, i.e., the relative rates of solvent evaporation and solute diffusion. Herein, we studied processing effects that drive bottlebrush additives to interfaces when blended with linear polymers. We prepared blends of bottlebrush polystyrene (BBPS) and linear perdeuterated polystyrene (dPS), where the BBPS sidechain length was fixed at N sc = 48, the BBPS backbone length ranged from N b = 30−260, and the dPS chain length ranged from N m = 40−548. The relative Pe numbers of BBPS and dPS were varied by changing the solvent and sizes of BBPS and dPS. In contrast to other binary blends where the constituents have disparate sizes (e.g., colloid/colloid, polymer/colloid, and polymer/polymer), we found that the relative Pe number cannot account for the degree of segregation observed in these bottlebrush and linear polymer blends. For a fixed BBPS side-chain length, we observe stronger surface segregation of bottlebrush additives when the blend is cast using lower boiling point solvents and/or for blends with longer bottlebrush polymers. We further show that solvent annealing of the film can increase the enrichment of bottlebrush additives near surfaces. This study provides insight into the interplay of processing effects and blend thermodynamics that govern surface segregation of bottlebrush polymer additives.

show abstract

Stratification of polymer–colloid mixturesviafast nonequilibrium evaporation

Abstract: In drying liquid films of polymer-colloid mixtures, the stratification in which polymers are placed on top of larger colloids is studied. It is often presumed that the formation of segregated...

Cited by 8 publications

References 42 publications

Heterogeneous Self-Assembly of a Single Type of Nanoparticle Modulated by Skin Formation

Heterogeneous Self-Assembly of a Single Type of Nanoparticle Modulated by Skin Formation

Self-Stratifying Coating with Robust and Durable Superhydrophobic Underlayer Constructed by Amphiphilic Janus Nanoparticles

Impact of Processing Effects on Surface Segregation of Bottlebrush Polymer Additives

Contact Info

Product

Resources

About