Congratulations to Melissa Gordon, selected for the “Excellence in Graduate Polymer Research” Symposium to be held at the ACS National Meeting in San Diego, March 2016. Selection to this symposium is a distinct honor and recognition in the polymer community. The symposium is being sponsored by the ACS Polymer Division and cosponsored by Presidential Event, Younger Chemists Committee, and Professional Relations Division.
Her presentation will be:
Dynamic Bonds in Covalently Crosslinked Polymer Networks for Photo-Activated Strengthening and Healing
Melissa B. Gordon, Jonathan M. French, Norman J. Wagner, Christopher J. Kloxin
A new class of photoresponsive materials is described in which an iniferter is built into the crosslinks of a polymer network to allow for a light-triggered, secondary polymerization which enables the material to simultaneously strengthen and heal under light. Unlike other two-tiered polymerization systems that require a leachable photoinitiator to impart dynamic nature to the network, the responsive nature of this material is inherent to the network itself via the light-triggered dissociation of its own crosslinks. Specifically, an iniferter crosslinker containing a labile carbon-dithiocarbamate bond is incorporated into a polyurethane network and initiates a light-triggered, free radical polymerization, thus increasing the modulus by two orders of magnitude. The final modulus is tuned a priori by adjusting the concentration of the polymerizable group initially present in the formulation. We show the versatility of this new approach with three demonstrations: 1) photo-induced healing, reforming, and strengthening of a specimen after it has been severed, (2) photopatterning to spatiotemporally control property changes post-cure, and (3) cold-working the polymer film into a 3D configuration and then using light to “lock-in” the film’s shape. The simplicity and versatility of this iniferter-based, two-tiered polymerization is readily translatable to other purposes, such as functionalizing surfaces, wrinkling and beyond.