Ionic Liquid Polymer Solutions Stabilized by Transition Metal Complexes
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Solution Overview
Problem
Current polymer solutions, particularly those using NMMO and ionic liquids, face issues with thermal and rheological instability, leading to degradation and decreased polymerization degree, which affects fiber quality and process viability, with existing stabilization methods either failing to provide adequate thermal stability or introducing unwanted metal residues in the final product.
Innovation Solution
Incorporating low concentrations of inorganic salts of transition metals, such as Cu, Co, Ni, Mn, Zn, or Ag, into polymer solutions dissolved in ionic liquids, which form complexes with the solvent and polymer, enhancing thermal and rheological stability and allowing for consistent spinning conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If high temperatures are used to reduce viscosity and enable deformation of concentrated cellulose solutions, then the deformability of the solution is improved, but the thermal stability deteriorates leading to solvent degradation and decreased degree of polymerization
Solution Approach 1:
The patent introduces transition metal salts (Cu, Co, Ni, Mn, Zn, or Ag) as stabilizing additives that change the chemical parameters of the solution system. These metals form complexes with the solvent and polymer, fundamentally altering the thermal and rheological properties of the solution, enabling it to maintain stability at lower temperatures while remaining deformable.
Solution Approach 2:
Transition metal salts act as intermediary substances that mediate between the solvent and polymer, forming complex structures that stabilize the system. The metal ions serve as bridging elements that create a more stable coordination environment, preventing direct degradation reactions between the solvent and polymer at elevated temperatures.
2Temperature
If NMMO is used as solvent at temperatures above 90°C to maintain molten state, then the solvent remains in usable state, but degradation reactions are accelerated leading to discoloration and decreased degree of polymerization
Solution Approach 1:
The transition metal salts are added in advance to the solution system to prevent degradation reactions before they occur. The metals form protective complexes with the solvent and polymer, creating a stabilized system that resists thermal degradation even when heated to necessary processing temperatures, thereby counteracting harmful degradation effects proactively.
3Productivity
If basic compounds are added to increase dissolution rate and lower viscosity, then the solution processability is improved, but the thermal stability deteriorates due to increased acidity at C-2 of imidazolium IL promoting reactions with cellulose
Solution Approach 1:
Instead of using basic compounds that alter pH and create stability issues, the patent employs transition metal salts that change the chemical environment through complex formation. This alternative parameter change achieves solution processability improvement without the detrimental pH-related side effects, maintaining thermal stability while enhancing dissolution and reducing viscosity.
4Quantity of substance
If metallic cations are used as components of ionic liquids to improve dissolving properties, then the dissolution capability is improved, but residual metal contents in the final product increase requiring greater processing effort
Solution Approach 1:
The patent separates the stabilizing function from the ionic liquid composition itself. Instead of incorporating metallic cations into the IL structure, transition metal salts are added as separate stabilizing agents in minimal concentrations (0.01-1% by weight). This extraction approach provides the necessary dissolution enhancement while minimizing residual metal content in the final fiber product, reducing downstream processing requirements.
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 addition of transition metal salts significantly increases thermal stability, reduces solvent degradation, and improves the mechanical properties of fibers, while minimizing residual metal content in the final product, enabling lower processing temperatures and more efficient spinning processes.
Implementation Method 1
adding salt compounds of transition metals, for example Cu, Co, Ni, Mn, Zn or Ag cations, which form complexes with the solvent and with the polymer, in particular with the cellulose
Implementation Method 2
a polymer solution which is obtained by dissolving polymers, the polymers being cellulose or their fiber-forming derivatives, in an ionic liquid or a mixture of ionic liquid
Data Source
AI summary
Rheologically and thermally stabilized polymer solution, in which the polymers are dissolved in ionic liquids or a mixture of ionic liquids and non-solvent, where the polymer solution contains at least one complexing transition metal compound in a concentration of 0.01-1 wt.%, relative to the weight of the polymers, is claimed. Independent claims are included for: (1) preparing a polymer solution comprising maintaining the temperature during the solvent, storage and spinning process below 110[deg] C, preferably in the range of Is 45-80[deg] C; and (2) moldings produced from the polymer solution, where the polymer is regenerated in the form of fibers, nonwovens, films, beads, flakes or foams.