Synthesis and Properties of Chemically Recyclable Polyurethane Elastomer Containing Polyacetal Soft Segment

Hydroxy-terminated telechelic polyacetals (PHBVE) were synthesized by polyaddition of 4-hydroxybutyl vinyl ether (HBVE; CH_2=CH-O-CH_2CH_2CH_2CH_2-OH) in presence of 1,4-butanediol (BD) with an acid catalyst in tetrahydrofuran (THF) at 0℃. Polyurethane elastomers with polyacetal soft segments (PHBVE-PU) were synthesized by the reaction of PHBVE with an excess amount of 4,4'-diphenylmethane diisocyanate and the subsequent chain-extension reaction with BD. PHBVE-PU (e.g., M_n, 49000; M_n of polyacetal prepolymer, 930) exhibited low glass trasition temperature (-24℃), high thermal stability (thermal decomposition temperature, 295℃), and good elastomeric properties (tensile strength, 11.2MPa; elongation at break, 610%). PHBVE-PU underwent smooth degradation with the treatment of aqueous acid in tetrahydroturan (THF) at room temperature to give BD in 74% yield and urethane hard segment residues as de gradation products