Sulfonated Polyethylene with Periodic Acid Groups
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for synthesizing sulfonated polymers, such as sulfonated polyethylene, result in random placement of functional groups, leading to uncontrolled acid aggregation and limited structural organization, which is undesirable for applications like proton conducting membranes.
Innovation Solution
The development of sulfonated polyethylene with periodically or quasiperiodically separated sulfonic acid groups along the polymer backbone, achieved through acyclic diene metathesis polymerization and subsequent hydrogenation and saponification, allowing for controlled placement and separation of sulfonic acid units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If random copolymerization methods are used to synthesize sulfonated polymers, then the synthesis process is simple and widely applicable, but the functional groups are randomly placed leading to uncontrolled acid aggregation and poor structural organization
Solution Approach 1:
The patent introduces a preliminary organizing step where a directing agent or template is introduced during polymerization to pre-establish the desired periodic arrangement of functional groups. This allows the polymerization to proceed with controlled placement rather than random distribution, resolving the contradiction between manufacturing simplicity and structural precision.
Solution Approach 2:
The patent employs an intermediary substance (directing agent, template, or catalyst) that mediates the polymerization process to ensure periodic placement of functional groups. This intermediary controls the spatial arrangement during synthesis, enabling precise functional group placement while maintaining a relatively simple overall process.
2Manufacturing precision
If vinyl copolymerization is used to create alternating copolymers, then the functional groups are placed at regular intervals of three carbon atoms, but the number of covalently bonded carbon atoms between functionalized carbons is restricted
Solution Approach 1:
The patent changes the fundamental parameters of the polymerization approach by moving from vinyl copolymerization (which fixes spacing at three carbons) to step-growth polymerization or ring-opening polymerization of cyclic monomers. This parameter change allows flexible control of the number of carbon atoms between functional groups while maintaining periodic regularity, thus resolving the contradiction between precision and adaptability.
3Manufacturing precision
If ring-opening polymerization of cycloalkene monomers is used, then the placement of functional groups can be controlled, but the ring size is limited to seven or eight atoms due to synthesis difficulty and cost
Solution Approach 1:
The patent inverts the traditional approach by first creating linear monomers with the desired number of carbon atoms between functional groups, then using these linear monomers in step-growth polymerization. This inversion bypasses the ring-size limitation entirely, allowing any desired spacing while maintaining periodic placement control through the monomer design.
4Manufacturing precision
If sulfonic acid groups are placed periodically along the polymer backbone, then structural organization and proton conductivity are improved, but the synthesis process becomes more complex requiring multiple steps
Solution Approach 1:
The patent performs preliminary placement of protecting groups or directing moieties on monomers before polymerization, or introduces a template during polymerization that directs periodic functional group placement. This preliminary organization enables the subsequent deprotection or removal steps to yield periodically sulfonated polymers, trading some process complexity for precise structural control.
Solution Approach 2:
The patent uses an intermediary template or directing agent during polymerization that facilitates periodic placement of functional groups. This intermediary is later removed or transformed, leaving the desired periodic structure. The intermediary mediates the complexity by providing a temporary organizational framework that simplifies the overall synthetic strategy.
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 enables the formation of sulfonated polyethylene with regular sulfonic acid group placement, enhancing structural organization and potential for improved proton conductivity and ion transport in membranes.
Implementation Method 1
The ring opening metathesis copolymerization, ROMP, for example, of a carboxylic acid functionalized cyclooctene with cyclooctene
Implementation Method 2
subsequent hydrogenation of the double bounds of the polymer formed upon olefin metathesis
Implementation Method 3
ADMET polymerization of one or more sulfonic ester substituted α,ω-alkyldienes, where at least one methylene unit separates the terminal ene groups from the sulfonic ester substituted methylene unit, subsequent hydrogenation of the ene units in the resulting polymer, and subsequently the hydrolysis of the sulfonic ester to the sulfonic acid
Data Source
AI summary
A sulfonated polyethylene is achieved where a polymethylene backbone with substituted methylene units having one or two sulfonic acid groups or salts of the sulfonic acid groups periodically, quasiperiodically, or quasirandomly separated from each other by unsubstituted methylene units along the polymer backbone. The sulfonated polyethylene is prepared by suspending a sulfonated ester polyethylene in a polar aprotic non-solvent, whereupon the addition of a strong base saponifies the esters with the dissolving of the resulting sulfonated polyethylene having salts of sulfonic acid groups.