Safe and Scalable Syntheses of N,N-Dimethyltrifluoromethanesulfonamide (DMTMSA) and Other Trifluoromethanesulfonamide Solvents for High Energy Density Battery Applications.

A simple, scalable synthetic methodology for the synthesis of N,N-dimethyltrifluoromethanesulfonamide (DMTMSA) and other trifluoromethanesulfonamide solvents is described. No specialized glassware is required, water is the solvent, and an ice bath is used for cooling. Up to 155 g of DMTMSA is synthesized in a single batch in 92% yield. The optimized process is highly mass efficient (PMI = 9.1), and excess dimethylamine may be recovered (93% recovery, 51% decrease in waste) and recycled via a simple short-path distillation.

Defining Reactivity-Deconstructability Relationships for Copolymerizations Involving Cleavable Comonomer Additives.

The incorporation of cleavable comonomers as additives into polymers can imbue traditional polymers with controlled deconstructability and expanded end-of-life options. The efficiency with which cleavable comonomer additives (CCAs) can enable deconstruction is sensitive to their local distribution within a copolymer backbone, which is dictated by their copolymerization behavior. While qualitative heuristics exist that describe deconstructability, comprehensive quantitative connections between CCA loadings, reactivity ratios, polymerization mechanisms, and deconstruction reactions on the deconstruction efficiency of copolymers containing CCAs have not been established. Here, we broadly define these relationships using stochastic simulations characterizing various polymerization mechanisms (e.g., coltrolled/living, free-radical, and reversible ring-opening polymerizations), reactivity ratio pairs (spanning 2 orders of magnitude between 0.01 and 100), CCA loadings (2.5% to 20%), and deconstruction reactions (e.g., comonomer sequence-dependent deconstruction behavior). We show general agreement between simulated and experimentally observed deconstruction fragment sizes from the literature, demonstrating the predictive power of the methods used herein. These results will guide the development of more efficient CCAs and inform the formulation of deconstructable materials.

Tricyclononenes and tricyclononadienes as efficient monomers for controlled ROMP: understanding structure-propagation rate relationships and enabling facile post-polymerization modification.

Grubbs 3rd-generation (G3) pre-catalyst-initiated ring-opening metathesis polymerization (ROMP) remains an indispensable tool in the polymer chemist's toolbox. Tricyclononenes (TCN) and tricyclononadienes (TCND) represent under-explored classes of monomers for ROMP that have the potential to both advance fundamental knowledge (e.g., structure-polymerization kinetics relationships) and serve as practical tools for the polymer chemist (e.g., post-polymerization functionalization). In this work, a library of TCN and TCND imides, monoesters, and diesters, along with their exo-norbornene counterparts, were synthesized to compare their behaviors in G3-initiated ROMP. Real-time 1H NMR was used to study their polymerization kinetics; propagation rates (k p) were extracted for each monomer. To understand the relationships between monomer structure and ROMP propagation rates, density functional theory methods were used to calculate a variety of electronic and steric parameters for each monomer. While electronic parameters (e.g., HOMO energy levels) correlated positively with the measured k p values, steric parameters generally gave improved correlations, which indicates that monomer size and shape are better predictors for k p than electronic parameters for this data set. Furthermore, the TCND diester-which contains an electron-deficient cyclobutene that is resistant to ROMP-and its polymer p(TCND) are shown to be highly reactive toward DBU-catalyzed conjugate addition reactions with thiols, providing a protecting- and activating-group free strategy for post-polymerization modification.

Thiol-triggered deconstruction of bifunctional silyl ether terpolymers via an SNAr-triggered cascade.

While Si-containing polymers can often be deconstructed using chemical triggers such as fluoride, acids, and bases, they are resistant to cleavage by mild reagents such as biological nucleophiles, thus limiting their end-of-life options and potential environmental degradability. Here, using ring-opening metathesis polymerization, we synthesize terpolymers of (1) a "functional" monomer (e.g., a polyethylene glycol macromonomer or dicyclopentadiene); (2) a monomer containing an electrophilic pentafluorophenyl (PFP) substituent; and (3) a cleavable monomer based on a bifunctional silyl ether . Exposing these polymers to thiols under basic conditions triggers a cascade of nucleophilic aromatic substitution (SNAr) at the PFP groups, which liberates fluoride ions, followed by cleavage of the backbone Si-O bonds, inducing polymer backbone deconstruction. This method is shown to be effective for deconstruction of polyethylene glycol (PEG) based graft terpolymers in organic or aqueous conditions as well as polydicyclopentadiene (pDCPD) thermosets, significantly expanding upon the versatility of bifunctional silyl ether based functional polymers.

Orthogonally deconstructable and depolymerizable polysilylethers via entropy-driven ring-opening metathesis polymerization.

The synthesis of novel polysilylethers via entropy-driven ring-opening metathesis polymerization (ED-ROMP) of cyclic bifunctional silyl ether-based monomers is reported. These polymers display good thermal stability and ultra-low Tg (-88 °C). Moreover, they are rapidly deconstructable via the cleavage of the silicon-oxygen linkages with acid or fluoride triggers, and they were partially depolymerizable by the addition of exogenous metathesis catalyst. Analysis of the deconstructed polymer products provided insight into the polymer microstructure, showing that the ED-ROMP process was regiorandom. Altogether, this work offers a new class of deconstructable polymers with a range of potential applications.