Degradation of poly(1,4-phenylene sulfide) on exposure to chlorinated water

Experiments were performed to characterize events pertinent to the degradation of poly(1,4-phenylene sulfide) upon exposure to chlorinated water. Studies were specifically undertaken to identify the reactive species involved in the degradation reactions. Species of concern are Cl2, HOCl, and singlet molecular oxygen, O2(a1Δg), all of which exist in chlorinated water and whose concentration profiles are pH-dependent. Polymer degradation was monitored in pH-dependent experiments using FTIR spectroscopy. Data obtained indicate that Cl2 and HOCl are the principal reactive species that initiate degradation, and that the pertinent reactions occur over the pH range of ∼2-8. Reaction products include not just the sulfoxide and sulfone, but species derived from the chlorination of the aromatic ring and subsequent ring oxidation. Spatially-resolved FTIR mapping experiments illustrate how the progress of the reactions depends on the diffusion of reactive species from the surface of a given sample into the bulk. These results are important with respect to the development of polymers that can better resist exposure to water that has been chlorinated to kill bacteria.