(296a) Nanoparticles Catalyze Rapid Hydrolysis of Poly(lactic acid) in Downhole Conditions

Poly(lactic acid) (PLA), a bio-based degradable polymer, has been used in the oilfield service industry for multistage hydraulic fracturing.    The rate of PLA degradation depends on the rate of ester hydrolysis, which is significantly reduced below the glass transition temperature (T_g) of PLA. This limits the applications of PLA in downhole formations (type of rocks) to only high temperatures. A simple, ready-to-scale-up chemistry using zinc oxide nanoparticles to catalyze the hydrolysis of PLA results in rapiddegradation of PLA and extends its applications to low-temperature shale formations. Furthermore, for the first time, we have applied a nondestructive analytical method of ¹H T₂ NMR relaxometry to measure the apparent rate constants of PLA hydrolysis in solid, heterogeneous, composite systems that have multiple and complex reaction kinetics. The demonstrated activation energy for ZnO-catalyzed PLA hydrolysis is about 38% lower than that of pure PLA hydrolysis.