Mass Spectrometry Imaging of Time-Dependently Photodegraded Light Stabilizers in Polyethylene Films Using...

Area of Science:

• Polymer Science
• Analytical Chemistry
• Materials Science

Background:

• Light stabilizers are essential additives for enhancing polymer durability and performance.
• Understanding additive degradation mechanisms is critical for designing advanced polymer materials.
• Existing analytical techniques face challenges in elucidating additive distribution and degradation pathways within polymers.

Purpose of the Study:

• To investigate the distribution and molecular structure of photodegradation products of oligomeric hindered amine light stabilizers (o-HALS) in polyethylene films.
• To establish a method for preparing polymer films with controlled photodegradation regions to study light irradiation time effects.
• To elucidate the photodegradation mechanism of o-HALS in polymer materials using advanced mass spectrometry imaging techniques.

Main Methods:

• Utilized tapping-mode scanning probe electrospray ionization mass spectrometry imaging (t-SPESI-MSI) to analyze additive distribution and changes over time.
• Employed liquid extraction surface analysis tandem mass spectrometry (LESA-MS/MS) to identify the molecular structure of degradation products.
• Developed a novel method for creating polymer films with multiple photodegradation zones to correlate degradation with light exposure duration.

Main Results:

• t-SPESI-MSI demonstrated a decrease in o-HALS signal intensity and progressive changes in degradation products with increasing light irradiation time.
• LESA-MS/MS identified that degradation products result from the fragmentation of o-HALS within the polymer matrix.
• The study proposes a detailed mechanism involving multiple, stepwise reactions for the formation of photodegradation products.

Conclusions:

• The combined application of t-SPESI-MSI and LESA-MS/MS provides a powerful approach for direct analysis of o-HALS photodegradation in polymers.
• This methodology enables a comprehensive understanding of degradation mechanisms, paving the way for improved polymer stabilization strategies.
• The findings are crucial for the development of more resilient and longer-lasting polymer materials.