PEDOT:PSS Liquid Composition Azeotrope Drying Control
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Solution Overview
Problem
Aqueous PEDOT/PSS-dispersions used in conductive polymer layers dry too quickly, leading to clogging of application devices and a reduction in sheet resistance, which is undesirable for applications like antistatic coatings and electromagnetic radiation shields.
Innovation Solution
A liquid composition comprising a complex of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid in a solvent mixture that forms an azeotrope with water, including diacetone alcohol, with additives like UV-stabilizers and rheology modifiers, to control drying speed and maintain high sheet resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-boiling solvents such as ethylene glycol and DMSO are added to reduce drying speed, then drying speed is reduced, but sheet resistance significantly decreases which is not desired
Solution Approach 1:
The patent changes the chemical composition parameters by using a specific organic solvent (acetone) with particular boiling point and solubility characteristics, rather than conventional high-boiling solvents. This parameter change allows achieving reduced drying speed without the harmful side effect of significantly reduced sheet resistance.
Solution Approach 2:
The patent introduces an intermediary substance - a specific organic solvent that forms an azeotrope with water - which mediates between the conflicting requirements of drying speed and sheet resistance. This intermediary enables controlled evaporation while maintaining the electrical properties of the conductive polymer layer.
2Ease of manufacture
If aqueous PEDOT/PSS-dispersions are used, then processability is good, but they dry too fast leading to clogging of application devices
Solution Approach 1:
The patent modifies the solvent composition parameters by adding a specific organic solvent to the aqueous dispersion, changing the evaporation characteristics while maintaining the dispersion's processability and compatibility with PEDOT/PSS.
Solution Approach 2:
The patent creates a composite solvent system combining water and a specific organic solvent in defined ratios. This composite material leverages the benefits of both components: the processability and conductivity enhancement from aqueous PEDOT/PSS and the controlled evaporation rate from the organic solvent.
3Ease of operation
If the drying speed is reduced by adding high-boiling solvents, then clogging is prevented, but the sheet resistance reduces significantly which compromises conductivity
Solution Approach 1:
The patent changes the physical parameters of the solvent system by selecting an organic solvent with specific boiling point (166°C for acetone) and water solubility characteristics, achieving extended open time without compromising the final conductivity of the dried layer.
Solution Approach 2:
The patent uses a volatile organic solvent (acetone) that evaporates completely during the drying process, leaving no residual effect on the conductive polymer's properties. This approach temporarily modifies drying behavior during application but leaves the final product with desired conductivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition prevents clogging of application devices and maintains high sheet resistance, ensuring effective use in conductive layers for antistatic coatings and electromagnetic radiation shields without compromising conductivity.
Implementation Method 1
at least one organic solvent iib) capable of forming an azeotrope with water iia)
Implementation Method 2
particles comprising a complex of a polythiophene and a polyanion
Data Source
AI summary
The present invention relates to a liquid composition comprising i) particles comprising a complex of a polythiophene and a polyanion; ii) a liquid phase, wherein the liquid phase comprises iia) water and iib) at least one organic solvent having - a boiling point, determined at a pressure of 1013 mbar, in the range from 110 to 250°C and - a solubility in water, determined at 25°C, of at least 10 wt.-%, wherein the liquid phase is an azeotrope or is capable of forming an azeotrope. The invention also relates to a process for the preparation of a layered body, to the layered body obtainable by such a process and to the use of a liquid composition.