Keio University · Materials Science
Professor Atsushi Hotta's research lab specializes in the design and synthesis of advanced polymeric materials with tailored microstructures and mechanical properties. The lab focuses on block copolymers—particularly semicrystalline and thermoplastic elastomers—exploring their phase behavior, morphology, and dynamic mechanical responses. Key research directions include the control of microphase separation, stress relaxation dynamics in complex soft materials, and the interplay between molecular architecture and macroscopic properties. The lab also investigates liquid crystalline elastomers and their relaxation behavior during structural transitions.
Figures are computed from collected data and may differ slightly.
We report the design, synthesis, morphology, phase behavior, and mechanical properties of semicrystalline, polyolefin-based block copolymers. By using living, stereoselective insertion polymerization catalysts, syndiotactic polypropylene-block-poly(ethylene-co-propylene)-block-syndiotactic polypropylene and isotactic polypropylene-block-regioirregular polypropylene-block-isotactic polypropylene triblock copolymers were synthesized. The volume fraction and composition of the blocks, as well as th
We study thermoplastic elastomers of triblock copolymers, of the form polystyrene−polyisoprene−polystyrene (SIS), where the microphase-separated PS blocks act as physical cross-links for the PI elastic network. Two compositions are examined: one with micellar cubic and the other with hexagonal cylindrical morphology of PS. Remarkably, the long-time stress relaxation is very similar; it reveals a continuous crossover between the typical response of a classical rubber at low temperatures and that
We study the slow relaxation of stress in polydomain acrylate liquid crystalline elastomers undergoing the alignment transition under an imposed extension. We analyse the long-time stress relaxation, the slow approach to the mechanical equilibrium and the role of time-temperature superposition. By building the master curves, we investigate extrapolated time intervals and show the presence of two distinct relaxation regimes. At the first stage, the fast power-law relaxation of stress, with the ex
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