Polyethyleneketones with Controlled Spacer Units: Synthesis, Characterization, and Photodegradation.

In this study, a new synthetic method for structurally controlled polyethyleneketones, a photodegradable polyethylene-like polymer, has been developed. Telechelic Zn-polyethylene was prepared from α,ω-diene, diethylzinc, and ethylene, which was allowed to react with diacid chlorides to give polyethyleneketones with defined spacing between the neighboring ketone functionalities. The photodegradation of these polymers under UV light demonstrated a degradation rate dependency on the spacer units between the carbonyl groups. The ones with longer-spaced ketones (6-18 carbons) showed efficient degradation, while shorter-spaced ketones (3-5 carbons) exhibited a slower degradation process. Structural analysis by solid-state FT-IR and DSC suggested the existence of carbonyl-carbonyl interactions in the shorter-spaced polymers, which are presumed to interfere with photodegradation via the Norrish reaction.