The difficulties surrounding polyaldehyde utilization stem from their low ceiling temperature (Tc), the temperature at which the polymerization and depolymerization are in equilibrium. Typical polyaldehyde Tc values are below 20oC, making them thermodynamically unfavorable at ambient temperatures. Using polyaldehydes above Tc requires the polymer chains to be kintetically stabilized via end caps or cyclization. Applications like transient technology can take advantage of these thermodynamic properties to create rapidly degradable devices that can evaporate to leave behind minimal residue. Cationically grown polyphthalaldehyde (pPHA) has proven to be a robust material that can rapidly degrade with catalytic amounts of acid. Copolymers of pPHA with aliphatic aldehydes offer a route to modify the processing and mechanical properties, as well as modifying the evaporation rate of the depolymerized materials after the device has been triggered to degrade. These copolymers have moduli on the order of 1 GPa and improved elongation-to-break by 60-200% compared to pPHA homopolymer, which makes polyaldehydes suitable for structural materials in transient devices. Post-polymerization modification has been carried out by crosslinking p(PHA-co-4-pentenal). Prescence of a higher volatility monomer helps the degradation products depress crystalization and evaporate at a faster rate than decomposed pPHA. A series of synthesized polycyclic aromatic hydrocarbons with a photoacid generator have been shown to photosensitize the degradation of polyaldehyde films across the visible spectrum. The Rehm-Weller equation is used to quantify the feasibility of the photo-induced electron transfer. Films hundreds of microns thick have been shown to completely depolyermize upon exposure to sunlight for 10 minutes.

Utilizing polyaldehydes in designing optically degradable systems for transient technology

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.