Weak covalent crosslinks in thermoset materials for increased toughness

This disclosure provides polymeric materials comprising weak crosslinking covalent bonds and/or weak crosslinking units comprising a weak covalent bond. Weak covalent bonds can be used in place of hydrogen bonds present in traditional polymeric materials (e.g., polyurethanes). Advantageously, the toughness can be controlled by varying the strength of weak covalent bonds and/or by varying the number of weak covalent crosslinks. Crosslinked materials applying the weak covalent crosslinking bonds can be used to create tough materials able to resist stress relaxation. Further, the present disclosure provides polymer chains and polymeric materials comprising inchain loops (also referred to herein as rings). The inchain loops comprise weak bonds and/or weak bridges comprising at least one weak bond. This disclosure also provides compositions comprising the polymer chains, materials comprising the polymer chains, monomer units that can react to form inchain loop-comprising polymer chains, resins comprising the monomer units, and related materials, appliances, and uses.