The scale-up of mechanochemical methods could play a transformative role in making manufacturing processes in the pharmaceutical industry greener by eliminating solvent use and recovery. Combined with energy-efficient continuous processing that consolidates reaction steps, mechanochemistry's environmental and economic benefits may translate across product supply chains. Here, we evaluate numerous sustainability and green chemistry metrics for producing nitrofurantoin, an active pharmaceutical ingredient (API), via mechanochemical continuous twin-screw extrusion (TSE) and conventional solvent-batch synthesis methods. We find a significant reduction in all metrics for TSE including energy, climate change, and human and ecological health, as well as cost due to reducing excess reactant consumption and eliminating solvents while maintaining high product selectivity. In addition, replacing the direct energy source to drive the chemical reaction from mostly thermal to electrical sources does not increase the net life cycle energy consumed to produce functionally equivalent API. We conclude that mechanochemical synthesis via TSE holds multiple sustainability benefits for manufacturing APIs and potentially other chemical products.

Many of the attractive properties in polymers are a consequence of their high molecular weight and therefore, scission of chains due to mechanochemistry leads to deterioration in properties and performance. Intramolecular cross‐links are systematically added to linear chains, slowing down mechanochemical degradation to the point where the chains become virtually invincible to shear in solution. Our approach mimics the immunoglobulin‐like domains of Titin, whose structure directs mechanical force towards the scission of sacrificial intramolecular hydrogen bonds, absorbing mechanical energy while unfolding. The kinetics of the mechanochemical reactions supports this hypothesis, as the polymer properties are maintained while high rates of mechanochemistry are observed. Our results demonstrate that polymers with intramolecular cross‐links can be used to make solutions which, even under severe shear, maintain key properties such as viscosity.

The mechanical properties of polymers are highly dependent on the mobility of the underlying chains. Changes in polymer architecture can affect inter‐ and intramolecular interactions, resulting in different chain dynamics. Herein, an enhancement in the mechanical properties of poly(butylmethacrylate) is induced by folding the polymer chains through covalent intramolecular crosslinking (CL). Intramolecular CL causes an increase in intramolecular interactions and inhibition of intermolecular interactions. In both the glassy and rubbery states, this molecular rearrangement increases material stiffness. In the glassy state, this molecular rearrangement also leads to reduced failure strain, but surprisingly, in the rubbery state, the large strain elasticity is actually increased. An intermediate intramolecular CL degree, where there is a balance between intra‐ and intermolecular interactions, shows optimal mechanical properties. Molecular dynamics simulations are used to confirm and provide molecular mechanisms to explain the experimental results.

Many of the attractive properties in polymers are a consequence of their high molecular weight and therefore, scission of chains due to mechanochemistry leads to deterioration in properties and performance. Intramolecular cross-links are systematically added to linear chains, slowing down mechanochemical degradation to the point where the chains become virtually invincible to shear in solution. Our approach mimics the immunoglobulin-like domains of Titin, whose structure directs mechanical force towards the scission of sacrificial intramolecular hydrogen bonds, absorbing mechanical energy while unfolding. The kinetics of the mechanochemical reactions supports this hypothesis, as the polymer properties are maintained while high rates of mechanochemistry are observed. Our results demonstrate that polymers with intramolecular cross-links can be used to make solutions which, even under severe shear, maintain key properties such as viscosity.

Single chain polymer nanoparticles (SCNP) are an attractive polymer architecture that provides functions seen in folded biomacromolecules. The generation of SCNPs, however, is limited by the requirement of a high dilution chemical step, necessitating the use of large reactors to produce processable quantities of material. Herein, the chemical folding of macromolecules into SCNPs is achieved in both batch and flow photochemical processes by the previously described photodimerization of anthracene units in polymethylmethacrylate (100 kDa) under UV irradiation at 366 nm. When employing flow chemistry, the irradiation time is readily controlled by tuning the flow rates, allowing for the precise control over the intramolecular collapse process. The flow system provides a route at least four times more efficient for SCNP formation, reaching higher intramolecular cross-linking ratios five times faster than batch operation.