Related Experiment Video
Updated: Jun 19, 2026
Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
Hydrogenation Kinetics Study: Precise Control of C=C Bonds in Polyisoprene (PI)-Containing Block Copolymers via
Luis Felipe Caspari Thiele1, Yongha Kim2, Corey A Roberts3
1Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
None:
Polydienes containing a C=C bond in each unit, such as polybutadiene (PBD)- or polyisoprene (PI)-containing polymers, have served as an important backbone of polymer applications in our daily lives. For versatile use of polydienes in various applications, C=C bonds in polydienes can be hydrogenated to achieve a desirable saturation level and/or additionally modified to obtain suitable structure-property sets. Among different hydrogenation procedures, non-catalytic, diimide hydrogenation using p-toluenesulfonyl hydrazide (TSH) can enable easier and precise control of hydrogenation level in C=C bonds at mild conditions. Here, for the first time, we reported a systematic hydrogenation kinetics study of one representative PI-containing polymer, i.e., polystyrene-b-polyisoprene-b-polystyrene (SIS) triblock copolymer with high molecular weight via TSH-based, diimide hydrogenation using NMR, SEC, and thermal analyses. We evaluated hydrogenation level (HL = 0∼99.9%) vs reaction time (0∼24 h) of SIS polymer and compared our kinetics results with other PBD- or PI-containing polymers with different chain architectures, compositions, and hydrogenation conditions to develop a universal efficacy of this diimide hydrogenation method and build a comprehensive understanding among these reports. We achieved HL = 51% in 1 h and HL > 99.9% by 24 h. Our analyses confirm that no side reactions occur up to 48 h without affecting other copolymer blocks. Our kinetics data align well with other similar polydienes but cover a wider range of reaction times (up to 48 h) than those in the literature. Using this information, a target hydrogenation level can be precisely achieved by controlling reaction time under mild conditions. Overall, this TSH-based diimide hydrogenation method is universal and effective over a broad range of PBD- and PI-containing polymers with different chain architectures and compositions.
Related Concept Videos
01:28Stability of Conjugated Dienes
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
02:13Reduction of Alkenes: Catalytic Hydrogenation
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
01:28Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
01:23Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...