Conjugated Thiophene Dimer Preparation for Capacitor Conductivity
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Solution Overview
Problem
The formation of unconjugated dimers and oligomers in polythiophene polymers disrupts conductivity, leading to increased equivalent series resistance (ESR) and leakage current in capacitors, making it difficult to achieve high conductivity in large-scale manufacturing processes.
Innovation Solution
A process involving heating a mixture of thiophene monomer and non-conjugated thiophene oligomer at temperatures between 100° C to 250° C, followed by polymerization, to convert non-conjugated dimers and oligomers into conjugated forms, resulting in a polymer with improved conductivity and reduced ESR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional in-situ polymerization is used to form polythiophene polymers, then the polymer can be formed and used as a conductive coating, but unconjugated dimers and oligomers are formed which disrupt conjugation and reduce conductivity
Solution Approach 1:
The patent applies preliminary action by pre-forming conjugated dimers and oligomers through controlled chemical polymerization before the main in-situ polymerization process. This pre-formed conjugated material is then incorporated into the polymerization mixture, ensuring that conjugated segments are already present before polymerization begins, thereby preventing disruption of conjugation continuity
Solution Approach 2:
The patent changes chemical parameters by using specific ratios of monomer to conjugated dimer/oligomer (e.g., 95:5 to 50:50 weight ratios), controlling reaction temperature, and adjusting oxidizer concentration to optimize the formation of conjugated structures while maintaining manufacturing feasibility
2Manufacturing precision
If Ullmann coupling is used to synthesize conjugated dimers and oligomers, then high ratios of conjugated structures can be achieved, but harsh chemicals and conditions are required making it unsuitable for large-scale manufacturing
Solution Approach 1:
The patent changes the chemical parameters by using milder oxidizers (FeCl3, FeBr3, FeI3, or persulfates) instead of the harsh conditions required for Ullmann coupling. The reaction is conducted in common solvents at controlled temperatures with monomer-to-dimer ratios optimized for scalability, maintaining high conjugation ratios while enabling large-scale manufacturing
Solution Approach 2:
The patent uses inexpensive, readily available materials such as iron-based oxidizers and common organic solvents that can be easily handled and disposed of, replacing the expensive and hazardous reagents required for Ullmann coupling, thereby improving ease of manufacture for large-scale production
3Manufacturing precision
If non-conjugated dimers are converted to conjugated dimers using dehydrogenating agents, then conjugated structures can be formed, but the process is not practical for manufacturing environments
Solution Approach 1:
Instead of converting non-conjugated dimers after formation, the patent performs preliminary action by directly forming conjugated dimers and oligomers through controlled chemical polymerization before incorporation into the final polymer. This eliminates the need for subsequent dehydrogenation steps and their associated manufacturing complexities
Solution Approach 2:
The patent extracts the problematic dehydrogenation step from the overall process by directly synthesizing conjugated structures in the first place. This removes the need for separate conversion steps involving dehydrogenating agents, simplifying the manufacturing process while maintaining high conjugation degrees
4Reliability
If acid is present in the oxidizer solution to prevent Fe3+ precipitation, then the polymerization can proceed, but acid promotes formation of non-conjugated linkages increasing ESR and leakage current
Solution Approach 1:
The patent changes the pH parameter by using weak acids (acetic acid, formic acid, or p-toluenesulfonic acid) at controlled concentrations (0.1-5% v/v) rather than strong acids. This maintains Fe3+ solubility while minimizing acid-catalyzed formation of non-conjugated linkages, thereby reducing ESR and leakage current while preserving polymerization stability
Solution Approach 2:
The patent introduces a mediator approach by using the weak acid as an intermediate that balances two competing requirements: maintaining Fe3+ solubility to enable polymerization while minimizing harmful acid-catalyzed side reactions. The weak acid acts as a buffer that prevents extreme pH conditions that would promote non-conjugated linkage formation
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
This approach enhances the degree of conjugation, leading to improved capacitor performance with lower ESR and increased polymer growth rate, allowing for better coating quality and reduced production cycles, thus making the process compatible with existing manufacturing facilities.
Implementation Method 1
heating the thiophene mixture at a temperature of at least 100° C. to no more than 250° C.
Implementation Method 2
followed by polymerizing the conjugated thiophene precursor
Data Source
AI summary
An improved process for forming a conjugated thiophene precursor is described as in the formation of an improved polymer prepared from the conjugated thiophene and an improved capacitor formed from the improved polymer. The improved process includes forming a thiophene mixture comprising thiophene monomer, unconjugated thiophene oligomer, optionally a solvent and heating the thiophene mixture at a temperature of at least 100° C. to no more than the lower of 250° C. or the boiling point of a component of said thiophene mixture with the lowest boiling point temperature.