Dipping versus spraying: exploring the deposition conditions for speeding up layer-by-layer assembly

Area of Science:

• Materials Science
• Polymer Chemistry
• Surface Science

Background:

• Polyelectrolyte multilayers (PEMs) are typically fabricated using layer-by-layer assembly via dipping.
• This method can be time-consuming and may face limitations with certain parameters like short contact times.

Purpose of the Study:

• To investigate and compare polyelectrolyte film fabrication using successive spraying versus classic dipping.
• To examine the influence of spraying parameters on multilayer film formation.

Main Methods:

• Fabrication of poly(styrenesulfonate)/poly(allylamine) films using successive spraying.
• Investigation of parameters: spraying time, polyelectrolyte concentration, and film drying.
• Characterization using atomic force microscopy (AFM) and X-ray reflectometry (XRR).

Main Results:

• Spray deposition provides easily controlled and reliable polyelectrolyte film fabrication.
• Multilayer thickness grows linearly with deposition cycles, similar to dipping.
• Spray deposition yields films with small surface roughness and can succeed where dipping fails (e.g., short contact times).
• The process can be accelerated by omitting the rinsing step due to continuous drainage.

Conclusions:

• Spray-based polyelectrolyte multilayer assembly is a rapid, reliable, and controllable alternative to dipping.
• This method produces high-quality films with low surface roughness.
• The technique offers advantages for specific conditions and process optimization.