Synthesis of Trifunctional Poly(propylene glycol) with Acetal Linkages and Properties of Chemically Recyclable Crosslinked Polyurethanes Prepared Therefrom

The synthesis and characterization of chemically recyclable crosslin.ked polyurethanes were studied in this work. Acetal units were introduced into polypropylene glycol having three hydroxyl terminal groups (PPG) by the reaction of the hydroxy groups of PPG with 4-acetoxybutyl vinyl ether followed by conversion of the acetate groups into hydroxy groups. Crosslinked polyurethanes were prepared by the reaction of the acetal-containing polyols (PPG-acetal-OH) with tolylene diisocyanates (TDI) at 120 °C under vacuum. The obtained polyurethanes formed elastomeric films and exhibited good mechanical properties. The treatment of the polyurethane films with aqueous acid at room temperature caused smooth hydrolysis of their acetal units to give PPG as a degradation product