Kyoto University · Chemical Engineering
Professor Hiroshi Watanabe's research lab specializes in the rheology, dielectric spectroscopy, and molecular dynamics of entangled polymer systems, particularly focusing on the relaxation mechanisms of complex macromolecular architectures such as block copolymers, star polymers, and binary blends. His work centers on understanding the dynamic tube model and its extensions—especially the dynamic tube dilation (DTD) mechanism—through which entanglements influence viscoelastic and dielectric responses in polymers with well-defined architectures and molecular weights. The lab investigates how chain topology, molecular weight distribution, and intermolecular interactions govern relaxation behavior, with a strong emphasis on experimental validation of theoretical models in complex polymer systems. Their studies often combine dielectric and mechanical measurements to probe segmental dynamics and constraint release effects in entangled networks.
Figures are computed from collected data and may differ slightly.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSlow Dielectric Relaxation of a Styrene-Isoprene-Styrene Triblock Copolymer with Dipole Inversion in the Middle Block: A Challenge to a Loop/Bridge ProblemHiroshi WatanabeCite this: Macromolecules 1995, 28, 14, 5006–5011Publication Date (Print):July 1, 1995Publication History Published online1 May 2002Published inissue 1 July 1995https://pubs.acs.org/doi/10.1021/ma00118a032https://doi.org/10.1021/ma00118a032research-articleACS PublicationsRequest reuse
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMeasurement of forces in symmetric and asymmetric interactions between diblock copolymer layers adsorbed on micaHiroshi Watanabe and Matthew TirrellCite this: Macromolecules 1993, 26, 24, 6455–6466Publication Date (Print):November 1, 1993Publication History Published online1 May 2002Published inissue 1 November 1993https://pubs.acs.org/doi/10.1021/ma00076a023https://doi.org/10.1021/ma00076a023research-articleACS PublicationsRequest reuse permissionsArt
For highly entangled cis-polyisoprene (PI) star polymers having more than 10 entanglements in each arm, dielectric and viscoelastic properties were examined within a context of the generalized tube model incorporating the dynamic tube dilation (DTD) mechanism. The star PI had the type A dipoles parallel along the arm backbone, and the global motion results in the viscoelastic as well as dielectric relaxation. The DTD relationship between the dielectric and viscoelastic relaxation functions Φ(t)
The molecular picture of dynamic tube dilation (DTD) was tested for viscoelastic and dielectric data for two series of entangled binary blends of linear cis-polyisoprenes (PI) having 10-3M2 = 308 and 10-3M1 = 94.0 or 21.4. The volume fraction υ2 of the high-M chains was varied from 0.005 to 0.5. The Struglinski−Graessley parameter rSG (= M2Me2M1-3), specifying the constraint release (CR) contribution to the relaxation of high-M chains at small υ2, was quite different for the two series of blends
Viscoelastic and dielectric experiments were conducted for entangled binary blends of linear cis-polyisoprenes (PI) having widely separated molecular weights, M1 = 21.4 × 103 ≅ 4Me and M2 = 308 × 103 ≅ 62Me with Me (≅5 × 103) being the entanglement molecular weight. The PI chain had type-A dipoles and its global motion (end-to-end vector fluctuation) was dielectrically active. The volume fraction of the high-M chain, υ2, was varied from 0.005 to 1. The Struglinski-Graessley parameter for the ble
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTViscoelastic properties and relaxation mechanisms of binary blends of narrow molecular weight distribution polystyrenesHiroshi Watanabe and Tadao KotakaCite this: Macromolecules 1984, 17, 11, 2316–2325Publication Date (Print):November 1, 1984Publication History Published online1 May 2002Published inissue 1 November 1984https://pubs.acs.org/doi/10.1021/ma00141a021https://doi.org/10.1021/ma00141a021research-articleACS PublicationsRequest reuse permission
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Hiroshi Watanabe, Tadao Kotaka, Takeji Hashimoto, Mitsushiro Shibayama, Hiromichi Kawai; Rheological and Morphological Behavior of Styrene‐Butadiene Diblock Copolymer Solutions in Selective Solvents. Journal of Rheology 1 April 1982; 26 (2): 153–179. https://doi.org/10.1122/1.5
Rheological and dielectric behavior was examined for concentrated solutions of a styrene−isoprene−styrene (SIS) triblock copolymer in monomeric and polymeric I-selective solvents, n-tetradecane (C14) and a low-M homopolyisoprene (I-1; M = 1.4K). The I blocks had symmetrically once-inverted dipoles along the block contour, and their midpoint motion was dielectrically detected. The SIS solutions exhibited rubbery, plastic, and viscous behavior at low, intermediate, and high temperatures (T). Diele
Abstract This article summarizes rheological features of moderately concentrated, diblock copolymer micellar solutions in selective solvents. In solvents of monomeric sizes, spherical micelles (with glassy cores) are arranged on cubic lattices to exhibit elasto‐plastic responses. These lattices are formed due to an osmotic constraint for the conformation of solvated corona blocks of the micelles. In polymeric solvents (homopolymers) chemically identical to the corona blocks, this constraint is s
Dielectric behavior was examined for solutions of a styrene-isoprene-styrene (SIIS) triblock and SI diblock copolymers in an I-selective solvent, n-tetradecane (C14). The SI copolymer had noninverted type-A dipoles in the I block while the SIIS copolymer, a head-to-head coupled dimer of SI, had once-inverted dipoles in the I block. At a low temperature (5 °C) where the S blocks formed glassy, spherical microdomains, the I blocks of SIIS had either the bridge or loop configurations. The loop frac
Nonlinear rheological behavior under uniaxial elongation was examined for unentangled melts of polystyrene (PS27; molecular weight M = 27k) and poly(p-tert-butylstyrene) (PtBS53; M = 53k) having nearly the same number of Kuhn segments per chain (nK = 30 and 35 for PS27 and PtBS53, respectively). For both materials, the steady state elongational viscosity, ηE, exhibited strain-rate-hardening and then strain-rate-softening on an increase of the Weissenberg number Wi ≥ 0.3 (Wi = ε̇τ1eq, with τ1eq a
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