A team from the Moore, Craig, and Kulik labs detail a non-scissile mechanophore built from an 8-thiabicyclo[3.2.1]octane 8,8-dioxide (TBO) motif that releases one equivalent of sulfur dioxide (SO2) from each repeat unit. These comprehensive studies of TBO mechanophore provide a mechanically coupled mechanism of multi-SO2 release from one polymer chain, facilitating the translation of polymer mechanochemistry to potential biomedical applications. Article Link

A team from the Klausen, Craig, and Kulik labs report the synthesis of two new examples of 7- and 8-membered sila-cycloalkynes, as well as an investigation of their strain-promoted reactivity with azides. The results demonstrate that measurable angle-strain alone is insufficient for room-temperature cycloaddition, influencing design principles in an area broadly relevant to organic chemists and chemical biologists. Article Link

In this article, researchers from the Klausen, Kulik, Moore, Kalow, Sottos, and Johnson labs highlight the use of a comonomer strategy for silyl ether exchange yielding deconstruction and bulk remolding in pDCPD thermosets. Article Link

In this Perspective, researchers from the Sottos and Craig labs speculate as to the potential match between covalent polymer mechanochemistry and recent advances in polymer network chemistry, specifically, topologically controlled networks and the hierarchical material responses enabled by multi-network architectures and mechanically interlocked polymers. Article Link

The Sottos, Johnson, and Moore labs demonstrate end-of-life deconstruction and upcycling of high-performance poly(dicyclopentadiene) (pDCPD) thermosets with a concurrent reduction in the energy demand for curing via frontal copolymerization. Article Link

A multi-institutional team from the Olsen, Moore, Nelson, Craig, and Kalow labs advance BigSMILES to accommodate a broad variety of non-covalent chemistry with a simple user-oriented, semi-flexible annotation formalism. Article Link

MONET Senior Investigators Jeremiah Johnson and Heather Kulik in collaboration with MONET postdoc Ilia Kevlishvili, MONET alum Nathan Oldenhuis, and others introduce a modular heterogenous catalysis platform in this latest publication in JACS. Article Link

Michael Rubinstein and collaborators at Duke, University of Hokkaido, and the Russian Academy of Sciences have developed a scaling theory of the elasticity of swollen and deswollen polymer networks. Article Link

Nicole Steinmetz and a team at University of California, San Diego formulated cowpea mosaic virus (CPMV) nanoparticles in injectable hydrogels to achieve slow particle release and prolonged immunostimulation, eliciting an antibody response that was sustained over 20 weeks in mouse models. Article Link

Mechanically Triggered Carbon Monoxide Release with Turn-On Aggregation-Induced Emission Polymers that release functional small molecules under mechanical stress potentially serve as next-generation materials for catalysis, sensing, and mechanochemical dynamic therapy. To further expand the function of mechanoresponsive materials, the discovery of chemistries capable of small molecule release are highly desirable. In this report, a MONET team details a nonscissile bifunctional mechanophore (i.e., dual mechano-activated properties) based on a unique mechanochemical reaction involving norborn-2-en-7-one (NEO). Yunyan Sun, William J. Neary, Zachary P. Burke, Hai Qian, Lingyang Zhu, and Jeffrey S. Moore Article Link

Toughening hydrogels through force-triggered chemical reactions that lengthen polymer strands Longer and stronger; stiff but not brittle: Hydrogels are highly water-swollen, cross-linked polymers. Although they can be highly deformed, they tend to be weak, and methods to strengthen or toughen them tend to reduce stretchability. A new paper out of MONET now reports a strategy to create more durable hydrogels. Wang et al. introduce a toughening mechanism by storing releasable extra chain length in the stiff part of a double-network hydrogel. A high applied force triggers the opening of cyclic strands that are only activated at high chain extension. Zi Wang, Xujun Zheng, Tetsu Ouchi, Tatiana Kouznetsova, Haley Beech, Sarah Av-Ron, Takahiro Matsuda, Brandon Bowser, Shu Wang, Jeremiah Johnson, Julia Kalow, Bradley Olsen, Jian Ping Gong, Michael Rubinstein, and Stephen Craig Free Full Article Link

Single-event Spectroscopy and Unravelling Kinetics of Covalent Domains Based on Cyclobutane Mechanophores Mechanochemical reactions that increase polymer contour length can serve as covalent synthetic mimics of the mechanical unfolding of noncovalent “stored length” domains in structural proteins. Here we report the force-dependent kinetics of stored length release in a family of covalent domain polymers based on cis-1,2-substituted cyclobutane mechanophores. The stored length is determined by the size (n) of a fused ring in an [n.2.0] bicyclic architecture, and it can be made sufficiently large (>3 nm per event) that individual unraveling events are resolved in both constant-velocity and constant-force single-molecule force spectroscopy (SMFS) experiments. Replacing a methylene in the pulling attachment with a phenyl group drops the force necessary to achieve rate constants of 1 s–1 from ca. 1970 pN (dialkyl handles) to 630 pN (diaryl handles), and the substituent effect is attributed to a combination of electronic stabilization and mechanical leverage effects. In contrast, the kinetics are negligibly perturbed by changes in the amount of stored length. The independent control of unravelling force and extension holds promise as a probe of molecular behavior in polymer networks and for optimizing the behaviors of materials made from covalent domain polymers. B. H. Bowser, S. Wang, T. B. Kouznetsova, H. K. Beech, B. D. Olsen, M. Rubinstein, and S. L. Craig, J. Am. Chem. Soc., online access. Article Link