Triggerable transient electronics are demonstrated with the use of a metastable poly(phthalaldehyde) polymer substrate and encapsulant. The rate of degradation is controlled by the concentration of the photo-acid generator and UV irradiance. This work expands on the materials that can be used for transient electronics by demonstrating transience in response to a preselected trigger without the need for solution-based degradation.

Thermally triggered transient electronics using wax-encapsulated acid, which enable rapid device destruction via acidic degradation of the metal electronic components are reported. Using a cyclic poly(phthalaldehyde) (cPPA) substrate affords a more rapid destruction of the device due to acidic depolymerization of cPPA.

Abstract

Polymeric materials that depolymerize into volatiles on command may function as vanishing substrates or packaging for transient electronics. Poly(vinyl tert-butyl carbonate sulfone) is known to afford low-boiling byproducts upon heat-activated degradation; however, the polymer is rather unstable, even to the degree of being difficult to process and handle. Understanding the origin of this instability is important for the development of robust materials capable of programmed self-destruction. In this work, we show that poly(vinyl tert-butyl carbonate sulfone)s thermally decompose via carbonate elimination as the rate-determining step, indicating that its thermal instability stems from the lability of the tert-butyl carbonate group. We further examined the effect of isomeric butyl carbonate side chains on the thermal degradation of poly(vinyl butyl carbonate sulfone)s and found that the degradation onsets range from 91 to 213°C, yielding as little as 2.77 ± 0.53 wt % residue. Results from our findings will aid in the development of vanishing polymers with tunable thermal degradation.

Thermally triggerable polymer films that degrade at modest temperatures (≈85 °C) are created from a blend of cyclic polyphthalaldehyde (cPPA) and a polymeric thermoacid generator, poly(vinyl tert-butyl carbonate sulfone) (PVtBCS). PVtBCS depolymerizes when heated, generating acid which initiates the depolymerization of cPPA into volatile byproducts. The mass loss onset for 2 wt% PVtBCS/cPPA is 22 °C lower than the onset for neat cPPA alone in dynamic thermogravimetric analysis experiments. Increased concentrations of PVtBCS increase the rate of depolymerization of cPPA. Raman spectroscopy reveals that the monomer, o-phthalaldehyde, is the main depolymerization product of the acid-catalyzed depolymerization of cPPA. The PVtBCS/cPPA blend is a promising material for the design and manufacture of transient electronic packaging and polymers.