Facile Synthesis of Polyhydroxylated Polybutadiene Derived from Hydroxyl-Terminated Polybutadiene via Thiol-Ene Click Reaction

Polyhydroxylated polybutadiene (PHPB) was synthesized via a thiol-ene click reaction between hydroxyl-terminated polybutadiene (HTPB) and 2-mercaptoethanol (ME) with 2,2'-azoisobutyronitrile (AIBN) as initiator. Effects of AIBN content, reaction time and temperature on the click reaction were investigated by determining hydroxyl value of the PHPB. The PHPB was characterized by FT-IR, 1H-NMR, 13C-NMR and GPC. Relative reactivity of three types of CC double bonds (1,2-vinyl, 1,4-cis and 1,4-trans units) in the HTPB reacting with the ME was discussed. The results showed that the optimal reaction conditions were that the AIBN content, reaction time and temperature were 2.0wt%, 180min and 70 degrees C, respectively. Under these conditions, the hydroxyl value of the PHPB was 3.12mmol center dot g-1 when the HTPB/ME mass ratio was 10:2. All three types of CC double bonds in the HTPB could react with the ME and the reactivity order was: 1,2-vinyl unit > 1,4-cis unit > 1,4-trans unit.