Mass Spectrometry Gains Popularity for Polymer Analysis

Mass spectrometry (MS) hasn’t always been the go-to technique for polymer analysis, with polymer scientists favoring more familiar techniques such as Gel Permeation Chromatography (GPC) or Nuclear Magnetic Resonance Spectrometry (NMR). However, MS is gaining popularity in the polymer analysis world. Polymer applications are becoming increasingly more sophisticated, be it the incorporation of sustainable and recycled polymers in consumer products, or the design of smart polymers in biomedical applications such as smart drug delivery systems (Frontiers in Materials, Computational Materials Science). This ever-increasing sample complexity means that analysts are constantly having to find new ways to examine their polymers, to fully understand their properties.  

Mass Spectrometry as a Tool for Materials Science 

In recent years, the development of MS has moved towards providing solutions that address the sample complexity and diversity often found in polymer analysis, offering multiple methods of sample introduction and ionization techniques. This means MS has evolved into a highly useful tool for materials science, enabling polymer chemists to investigate macromolecules, chain-by-chain. In contrast to other common tools for polymer characterization such as size exclusion chromatography, MS analysis of polymers can offer absolute mass determination with unrivalled accuracy. As described in a recent review:  

“The increasingly important role of high-resolution mass spectrometry is emphasized because of its unrivalled ability to describe unique species within polymer ensembles, rather than to report the average properties of the ensemble.” (Mass spectrometry as a tool to advance polymer science | Nature Reviews Chemistry) 

Overcoming Challenges with Polymer Mass Spectrometry 

The challenges in analyzing polymers by MS traditionally lie in their size or molar mass being outside the range applicable to the dynamic range of the instruments. However, a move to greener, more sustainable polymers often results in low molar masses and sometimes oligomeric-like structures being synthesized. Other challenges with polymer MS analysis include problems with desorbing and ionizing high molar mass polymers and in identifying the composition and structures of unique species given the sheer number of species in most polymer samples.  

The Waters™ Mass Spectrometry technology can help address some of the challenges in polymer analysis. Using the universal source, architecture analysts can access multiple ionization and chromatographic techniques, increasing the scope of polymers/materials that can be analyzed by MS. This universal architecture is also compatible with novel inlet technologies from third‐party manufacturers which you can easily utilize across the Waters systems, providing access to new and innovative techniques (e.g., the introduction of samples by direct insertion into a pyrolysis furnace for analysis by Gas Chromatography Mass Spectrometry). The introduction of atmospheric ionization techniques has opened the possibility of MS to the polymer industry, in particular the desorption, ionization, and structural interrogation of high-molar-mass macromolecules, as well as strategies to lower spectral complexity. 

Benefits and Enhancements of High-Resolution Mass Spectrometry 

High-resolution mass spectrometry (HRMS) in particular, allows a polymer analyst to make accurate mass measurements of monomer and oligomer confirmation and end-group determination, that can aid primary structure elucidation and confirmation.  

Applying tandem mass spectrometry to polymer analysis can: 

• Allow for structural interrogation of individual macromolecular chains  
• Offer the analyst an insight into specific polymer attributes including determination of the polymer sequence, sidechains, and end group functionalities 

The addition of ion mobility (IMS) to HRMS offers the ability to investigate and enhance the analysis of complex polymer mixtures, isomers, and higher-order molecular architectures based on a gas-phase separation inside a mass spectrometer using molecular size, shape, and charge.  

Other Technique Developments 

Although there is still some skepticism about the use of MS for polymer analysis, the developments in the technique have without doubt made MS more accessible to polymer scientists and positioned it as a complimentary technique to the likes of GPC and NMR. Other techniques increase the scope of samples which a suitable for MS such as: 

• Matrix Assisted Laser Desorption/Ionization  
• Time-of-Flight Mass Spectrometry (MALDI TOF MS) 
• Desorption Electrospray Ionization (DESI) 

Paired with IMS, the universal source architecture of our systems allows an analyst to explore polymer composition and architecture, positioning HRMS as a valuable tool in the design and development of advanced polymeric materials. 

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Resources

Mass spectrometry for polymers – White Paper

Mass Spectrometry Solutions for Polymer Research and Development (waters.com) 

Smart Polymers for Advanced Applications: A Mechanical Perspective Review

Mass spectrometry as a tool to advance polymer science | Nature Reviews Chemistry 

Additional Resources 

Blog: Accelerate Complex Materials Formulation Screening with Mass Spectrometry Analysis 

Blog: Supercharging Mass Spectrometry in the Fight Against SARS-COV-2