Controlled evaporative assembly of polymers from confined solutions

Three-Dimensional Coffee-Ring Effect Induced Deposition on Foam Surface for Enhanced Photothermal Conversion

Uniformly depositing a thin layer of functional constituents on porous foam is attractive to realize their concentrated interfacial application. Here, a simple but robust polyvinyl alcohol (PVA)-mediated evaporation drying strategy to achieve uniform surface deposition on melamine foam (MF) is introduced. Solutes can be accumulated homogeneously to the surface periphery of MF due to the enhanced coffee-ring effect of PVA and its stabilizing effect on various functional constituents, including molecules and colloidal particles. The deposition thickness is positively correlated with the feeding amounts of PVA but seems to be independent of drying temperature. 3D outward capillary flow driven by the combination of contact surface pinning and continual interfacial evaporation induces the forming of core-shell foams. The enhanced interfacial photothermal effect and solar desalination performance using PVA/polypyrrole-coated MF as a Janus solar evaporator are demonstrated.

Deposition of Quantum Dots in a Capillary Tube

The ability to assemble nanomaterials, such as quantum dots, enables the creation of functional devices that present unique optical and electronic properties. For instance, light-emitting diodes with exceptional color purity can be printed via the evaporative-driven assembly of quantum dots. Nevertheless, current studies of the colloidal deposition of quantum dots have been limited to the surfaces of a planar substrate. Here, we investigate the evaporation-driven assembly of quantum dots inside a confined cylindrical geometry. Specifically, we observe distinct deposition patterns, such as banding structures along the length of a capillary tube. Such coating behavior can be influenced by the evaporation speed as well as the concentration of quantum dots. Understanding the factors governing the coating process can provide a means to control the assembly of quantum dots inside a capillary tube, ultimately enabling the creation of novel photonic devices.

Self-assembly of large-scale P3HT patterns by confined evaporation in the capillary tube

Large-scale P3HT stripe patterns based on a controlled evaporation self-assembly method in a capillary tube have been fabricated.

Controlled evaporative self-assembly of poly(acrylic acid) in a confined geometry for fabricating patterned polymer brushes

A simple yet robust approach was exploited to fabricate large-scaled patterned polymer brushes by combining controlled evaporative self-assembly (CESA) in a confined geometry and self-initiated photografting and photopolymerization (SIPGP). Our method was carried out without any sophisticated instruments, free of lithography, overcoming current difficulties in fabricating polymer patterns by using complex instruments.

Microwave-assisted one-step patterning of aqueous colloidal silver

A new approach of utilizing microwave to pattern gradient concentric silver nanoparticle ring structures has been presented. The width and height of a single ring and the space between adjacent rings can be adjusted by changing the silver colloidal concentration and the microwave output power. By simply enhancing the ambient vapour pressure to the saturated value during microwave-assisted evaporation, sub-100 nm rings can be deposited in between adjacent micro-rings over a distance of millimetres. Combined with microwave sintering, this approach can also create conductive silver tracks in a single step, showing huge potential in fabricating micro- and nano-electronic devices in an ultra-fast and cost-effective fashion.

Evaporation of solutions and colloidal dispersions in confined droplets

We present a model that describes the drying of solutions and colloidal dispersions from droplets confined between two circular plates. This confined geometry, proposed by Clément and Leng [Langmuir 20, 6538 (2004)], casts a perfect control of the evaporation conditions, and thus also of the concentration kinetics of the solutes in the droplet. Our model, based on simple transport equations for binary mixtures, describes the concentration process of the solute inside the droplet. Using dimensionless units, we identify the different numbers that govern the concentration field of the solute, and we detail how to extract kinetic and thermodynamic information on the binary mixture from such drying experiments. We finally discuss, using numerical resolution of the model and analytical arguments, several specific cases: dilute solutions, a colloidal hard sphere dispersion, and a binary molecular mixture.