Polyaniline Coating via Photocurable Polymer Crosslinking
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Solution Overview
Problem
Current methods for forming electrically-conductive polyaniline patterns are complex and costly, requiring conductive substrates, multiple processing steps, and post-treatment with acidic solutions, making them unsuitable for roll-to-roll manufacturing and flexible applications.
Innovation Solution
A method involving a photocurable composition with water-soluble reactive polymers, crosslinked via [2+2] photocycloaddition, followed by aniline oxidation, to form durable and water-insoluble polyaniline patterns within or on crosslinked polymers, which serve as templates for emeraldine salt formation, allowing for high-resolution patterns without additional processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional chemical oxidative polymerization of polyaniline is used, then electrical conductivity is achieved, but the coating remains soluble in water and requires additional patterning and crosslinking steps
Solution Approach 1:
The patent combines the polymerization and crosslinking steps into a single simultaneous process. The water-soluble polymer with pendant crosslinkable groups serves dual function: as the dopant source for polyaniline formation and as the crosslinking matrix that provides water insolubility. This eliminates the need for separate patterning and crosslinking steps required in traditional methods.
Solution Approach 2:
The water-soluble polymer with pendant crosslinkable groups is pre-synthesized before the polymerization step. This preliminary preparation of the polymer backbone with built-in crosslinking capability allows the subsequent polymerization and crosslinking to occur simultaneously, reducing overall process complexity.
2Manufacturing precision
If lithographic patterning methods are used to form polyaniline patterns, then high resolution patterns are achieved, but the process becomes expensive and incompatible with roll-to-roll manufacturing
Solution Approach 1:
The patent replaces mechanical lithographic patterning methods with a chemical self-organizing approach. The water-soluble polymer with pendant groups spontaneously forms ordered structures during polymerization, eliminating the need for expensive lithographic equipment and complex mechanical patterning steps while maintaining high resolution.
Solution Approach 2:
The polymer system performs self-patterning through its inherent chemical structure. The water-soluble polymer with pendant crosslinkable groups automatically organizes into ordered patterns during the polymerization process, eliminating the need for external patterning tools and reducing manufacturing complexity.
3Manufacturing precision
If electropolymerization is used to form polyaniline films, then uniform conductive coatings are achieved, but conductive substrates are required which limits flexible application
Solution Approach 1:
The water-soluble polymer with pendant crosslinkable groups acts as an intermediary medium that enables polyaniline formation on non-conductive flexible substrates. This intermediary polymer provides the necessary chemical environment for polymerization and subsequent crosslinking, replacing the need for conductive substrates required in electropolymerization.
4Reliability
If strong acid doping is used to achieve electrical conductivity, then conductive polyaniline is formed, but the acid volatilizes from thin coatings reducing durability
Solution Approach 1:
The patent creates a composite structure where polyaniline is embedded within a crosslinked polymer matrix. The water-soluble polymer with pendant crosslinkable groups forms this matrix, which traps and retains the dopant acid, preventing its volatilization from thin coatings while maintaining electrical conductivity.
Solution Approach 2:
The patent changes the physical state and chemical environment of the dopant acid by incorporating it into a crosslinked polymer network. This parameter change from free acid to network-trapped acid prevents volatilization while maintaining the doping function necessary for electrical 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
Enables the creation of high-resolution, durable, and water-insoluble polyaniline patterns suitable for flexible substrates and roll-to-roll manufacturing, reducing complexity and cost while ensuring electrical conductivity.
Implementation Method 1
exposing the photocurable composition to radiation sufficient to cause crosslinking via [2+2] photocycloaddition of the (b) recurring units
Implementation Method 2
contacting the crosslinked polymer with an aniline reactive composition comprising an aniline monomer and up to 0.5 molar of an aniline oxidizing agent, in a molar ratio of from 1:0.5 to 1:1.5 of the aniline monomer to the aniline oxidizing agent, thereby forming an electrically-conductive polyaniline
Data Source
AI summary
A method is used to provide an electrically-conductive polyaniline pattern by providing a uniform layer of a photocurable composition on a substrate. The photocurable composition comprises a water-soluble reactive polymer comprising (a) greater than 40 mol % of recurring units comprising sulfonic acid or sulfonate groups, and (b) at least 5 mol % of recurring units comprising a pendant group capable of crosslinking via [2+2] photocycloaddition. The photocurable composition is exposed to cause crosslinking via [2+2] photocycloaddition of the (b) recurring units, thereby forming a crosslinked polymer. Any remaining water-soluble reactive polymer is removed. The crosslinked polymer is contacted with an aniline reactive composition having aniline monomer and up to 0.5 molar of an aniline oxidizing agent, thereby forming an electrically-conductive polyaniline disposed either within, on top of, or both within and on top of, the crosslinked polymer.