Engineering Polymers with Degradation and Recycling in Mind

While once a fictional idea, new degradable plastics now exist that are rugged enough to use as a structural material for rigid or flexible devices and depolymerize immediately upon triggering. The polymers can also be used as a temporary masking material or adhesive. Once depolymerized, the products can ‘disappear’ as a vapor, or be recovered with common solvents. Several modes of triggering can be used including chemical, thermal (a heat pulse) or optical triggering using ultraviolet or visible light.

These are not the kind of polymers that slowly degrade over a long period of time. The key to making a polymer disappear, or depolymerize, is having a low "ceiling temperature." Below the ceiling temperature, a polymer configuration is favored, but above that temperature, the polymer is thermodynamically unstable and will break apart into its component monomers by simply breaking one bond. Common polymers, like polystyrene, have a ceiling temperature far above ambient temperature and are very stable. To decompose them, you have to break many bonds.  Our patented polymers based on polyphthalaldehyde have a ceiling temperature below room temperature so that only a single bond needs to be broken to start a chain reaction leading to depolymerization of the entire polymer chain. The process can be initiated by specific chemicals, a temperature spike from an outside or embedded source, or by a stimuli-responsive catalyst. 

Our phthalaldehyde-based polymers are ideal resists for direct write patterning technologies, such as electron-beam, thermal scanning probe, and laser lithographies. Customizable copolymers offer the opportunity to optimize solubility, mechanical and optical properties, chemical reactivity, and thermal decomposition.