Collision induced dissociation study of ester-based polyurethane fragmentation reactions.

Area of Science:

• Analytical Chemistry
• Polymer Science
• Mass Spectrometry

Background:

• Polyurethanes (PURs) are versatile polymers with complex structures.
• Characterizing PURs in mixtures, especially with starting materials like polyesters, presents analytical challenges.

Purpose of the Study:

• To develop a method for distinguishing and characterizing different polyurethane structures within a complex mixture.
• To utilize fragmentation patterns and ion mobility for detailed polymer analysis.

Main Methods:

• Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) combined with collision-induced dissociation (CID).
• Ion mobility separations (IMS) were employed to analyze complex mixtures, including polybutylene adipate and PURs.
• A general fragmentation model for PURs was generated based on CID data.

Main Results:

• Two primary PUR fragmentation mechanisms were identified.
• The fragmentation model successfully differentiated linear vs. cyclic PURs, hard-block vs. soft-block PURs, and the degree of blockiness.
• The method allowed for the localization of MDI linkages and resolved isobaric species.

Conclusions:

• The combined MALDI-TOF MS/CID and IMS approach provides a powerful tool for detailed polyurethane characterization.
• This methodology enables the distinction of subtle structural variations in complex polymer mixtures.