Overcoming Barriers in PEEK Molecular Weight Testing.
Polyether ether ketone (PEEK) is a standout material in the world of high-performance polymers, prized for its strength, thermal stability, and chemical resistance. However, these same properties that make PEEK so valuable also make it notoriously difficult to analyze – especially when it comes to determining molecular weight using size-exclusion chromatography (SEC), also known as gel permeation chromatography (GPC).
At SGS PSI, we’re leveraging a powerful chemical strategy to overcome this challenge: derivatization with 1,2-ethanedithiol. This method significantly improves the solubility and chromatographic behavior of PEEK and similar polymers, enabling more accurate and reproducible SEC results.
The Challenge: SEC is a cornerstone technique for determining molecular weight distributions in polymers. But for PEEK, its semi-crystalline structure and limited to nonexistent solubility in any SEC solvent prevents analysis in its native form.
The Solution: Derivatization with 1,2-Ethanedithiol
1,2-Ethanedithiol (EDT) reacts with the carbonyl groups in PEEK’s backbone, forming thioacetal linkages. This chemical transformation disrupts intermolecular interactions and enhances solubility in organic solvents compatible with SEC, enabling the derivatized material to be tested under normal conditions.
How It Works:
Sample Preparation: PEEK is dissolved or suspended in a suitable reaction medium.
Derivatization: EDT is added under controlled conditions, reacting with ketone groups to form thioacetals.
Purification: The derivatized polymer is isolated and purified.
SEC Analysis: The modified polymer is now soluble and stable in SEC solvents, allowing for accurate molecular weight profiling.
Benefits of This Approach
Improved Solubility: Enables complete dissolution in SEC-compatible solvents.
Broader Applicability: Works with other ketone-containing high-performance polymers.
Compatibility: Integrates seamlessly with standard SEC systems and detectors.
Applications and Impact
This derivatization method is particularly valuable for:
Quality control of high-performance polymer batches
R&D of new PEEK-based materials
Comparative studies of polymer degradation or processing effects
By enabling reliable SEC analysis, this technique supports better decision-making in material selection, formulation, and performance prediction.
Looking Ahead
SGS PSI is actively refining this derivatization protocol and broadening its use across other challenging polymers. If your team is working with PEEK or similar materials and facing analytical hurdles, we’d be happy to collaborate or share our methodology.
