Potential PFAS products from thermal decomposition of munitions: a DFT analysis of pyrolysis products of fluoropolymers in the presence of energetic compounds

Per- and polyfluoralkyl substances (PFAS) are one of the most recalcitrant anthropogenic chemicals that can bioaccumulate and have carcinogenic properties. Their ubiquity in environmental matrices and resistance toward traditional disposal techniques pose a serious threat to the environment and public health. This thesis serves as a preliminary analysis of a novel source of PFAS, the disposal of munitions. Most munitions contain energetic compounds, to serve as the source of energy in detonation events, and fluoropolymers, to bind formulations as a means of stabilization, to seal the formulation away from the elements, or to serve as a fluorine source in pyrolants. Energetic compounds degrade through a variety of pathways, but the major pathways involve the formation of radicals and extreme heat. Despite the extreme recalcitrance of fluoropolymers, the conditions of detonation events are more than sufficient to initiate thermal decomposition in even the most robust fluoropolymers. The thermal decomposition of fluoropolymers involves highly reactive radical intermediates too. Since both energetic compounds and fluoropolymers undergo radical degradation mechanisms, PFAS radical recombination products are expected to be formed. There is little known about such potential PFAS products since they contain functionalities not seen in other sources of PFAS, so a summary of the synthesis and degradation reactions that these species are known to undergo from synthesis work is provided. This work also contains a detailed computational investigation of chemical bonding in such potential PFAS products from the pyrolysis of fluoropolymers in the presence of energetic compounds. Such investigations provide insight to the mechanisms of PFAS production and the types of functional groups to expect which provide guidance to the future analytical work by narrowing the scope of the system. The more that computational work is able to mimic experimental results, the more efficient future laboratory work will be. Thus, this thesis concludes by proposing possible future directions for this work, which includes a wide variety of ways to expand the system to be a more comprehensive representation of reality.

Name thesis:degree_name

Master of Science (M.S.)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Chemistry

Grantor dc:publisher

Colorado School of Mines. Arthur Lakes Library

Year dc:date.issued

2023

Author dc:creator

• Triumph, Zachary C.

Advisor dc:contributor.advisor

• Vyas, Shubham

Committee members dc:contributor.committeemember

• Domaille, Dylan
• Strathmann, Timothy J.

• chemical bonding
• density functional theory
• fluoropolymers
• per- and polyfluorinated alkyl substances
• PFAS

Statement dc:rights

• Copyright of the original work is retained by the author.

Language dc:language.iso

eng, English

Identifier

T 9593

OAI identifier oai:identifier

oai:repository.mines.edu:11124/178601