Transformation of Commodity Poly(hydroxyether of bisphenol A) into Vitrimers via Post Crosslinking with Hindered Urea Bonds

In this contribution, we reported the preparation of vitrimers by using commodity thermoplastics via post crosslinking with hindered urea bonds (HUBs). First, three hindered urea diisocyanates (HUDIs) were synthesized via the reactions of N,N'-di-tert-butylethylenediamine, N,N'-diethylethylenediamine, and piperazine with isophorone diisocyanate (IPDI). Thereafter, these HUDIs were used as the crosslinking agents to crosslink poly(hydroxyether of bisphenol A) (PH), a commodity thermoplastics. Fourier transform infrared (FTIR) spectroscopy and dynamic mechanical thermal analyses (DMTA) indicated that the PH thermosets were successfully obtained. It was found that the thermosets displayed the behavior of vitrimers. The PH thermosets can be reprocessed at elevated temperature without using catalyst and the mechanical strengths of vitrimers were recovered as high as 95%. The reprocessing properties are attributable to dynamic exchange reaction of hindered urea bonds, contingent on types of hindered urea bonds.