Subvitrimer

Subvitrimer is a term used in polymer science to describe a subset of dynamic covalent networks that share features with vitrimers but do not fully meet their defining criteria. In most usages, subvitrimers exhibit reversible bond exchange and potential for rearrangement under certain conditions, yet the extent of topology change is limited compared with true vitrimers, yielding intermediate properties between vitrimers and conventional thermosets.

The exchange reactions governing subvitrimers are typically associative, preserving cross-link density while enabling network rearrangement. Common chemistries include transesterification, transamidation, imine or dioxaborole exchange, and disulfide metathesis. In subvitrimers, reaction kinetics or accessibility are restricted by factors such as network crowding, catalysts, or gating motifs.

As a result, subvitrimers can show reprocessability and healing under elevated temperature or in the presence of a catalyst, but the process may require higher temperature, longer times, or catalysts than vitrimers. Mechanical properties at service conditions remain closer to those of traditional networks than to fully reconfigurable vitrimers.

Design strategies for subvitrimers focus on tuning exchange kinetics while maintaining network integrity. This includes choosing dynamic bonds with controllable activation barriers, placing exchange sites in accessible but constrained environments, and using latent catalysts to enable stepwise or gated exchange for partial network rearrangement.

The term is not yet universally standardized, and usages vary across studies. Subvitrimers are of interest for recyclable, repairable, and shape-memory materials that balance reformability with mechanical robustness. Ongoing work aims to clarify definitions and develop standardized testing to distinguish subvitrimers from vitrimers and conventional networks.