Papers - ASAI Makoto

Cluster growth from a dilute system in a percolation process

Fujinaga I., Yasuda T., Asai M., Chung U.i., Katashima T., Sakai T.

Polymer Journal (Polymer Journal)  52 ( 3 ) 289 - 297 2020.03

ISSN  00323896

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© 2019, The Society of Polymer Science, Japan. Abstract: The gelation process has been explained in the framework of percolation models. Although the percolation models accurately predict the gelation behaviors above the overlap concentration of prepolymers (c*0), they do not predict the gelation behaviors below c*0. We measured the osmotic pressure during the gelation of a series of model polymer gels, namely, tetra-polyethylene glycol (PEG) gels. The osmotic pressure decreased during the gelation reaction and was constant after the sol–gel transition. These results suggest that the clusters grow and fill the system at the sol–gel transition point. As a result, the gels behaved as semidilute systems regardless of the initial polymer concentration. This representation of the sol–gel transition at the overlap condition of the critical clusters corresponds well to the aggregation process predictrion. These results will help better understanding of general percolation problems in the dilute regime.

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Accurate Estimation of the Polymer Coverage of Hairy Nanoparticles

ASAI MakotoZHAO DanKUMAR K Sanat

Soft Matter (The Royal Society of Chemisry)  14 ( 38 ) 7906 - 7915 2018.08

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1744683X

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© The Royal Society of Chemistry. Understanding and predicting the mechanisms underpinning the self-assembly of polymer-grafted nanoparticles (PGNPs) are important for controlling the engineering applications of these novel materials. The self-assembly of these materials is driven by their surfactancy, i.e., by the fact that the (inorganic) nanoparticles energetically dislike the (organic) polymer tethers. In previous work we developed a model in which a grafted polymer chain was treated as a rigid equivalent sphere (ES) which was impenetrable to the NPs, but completely penetrable to other ESs. This description, along with a geometric analogy with patchy particles, allowed us to facilely explain the self-assembly of PGNPs. However, since we model an ES as being completely penetrable to other ESs but impenetrable to the NPs the physical correspondence between a “real” grafted polymer and an ES is not clear. The application of the ES model to experiments and to computer simulations has therefore seen limited success, and only qualitative agreement has been obtained. In this paper, we develop a more realistic description, termed the modified ES (mES) model, based on the work of Daoud and Cotton on curved polymer brushes, which takes the impenetrability of the individual chain monomers into account. While this approach increases the complexity of our formalism, we find that the resulting mES model quantitatively captures computer simulation results on the structure of the PGNPs and also quantitatively explains their self-assembly over a broad range of conditions.

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Surface Fluctuations Dominate the Slow Glassy Dynamics of Polymer-Grafted Colloid Assemblies

ASAI MakotoCACCIUTO AngeloKumar K Sanat

ACS Central Science (American Chemical Society)  4 ( 9 ) 1179 - 1184 2018.08

Research paper (scientific journal), Joint Work, Accepted,  ISSN  23747943

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© 2018 American Chemical Society. Colloids grafted with a corona layer of polymers show glassy behavior that covers a wide range of fragilities, with this behavior being tunable through variations in grafting density and grafting chain length. We find that the corona roughness, which is maximized for long chain lengths and sparse grafting, is directly correlated to the concentration-dependence of the system relaxation time (fragility). Relatively rougher colloids result in stronger liquids because their rotational motions become orientationally correlated across the whole system even at low particle loadings leading to an essentially Arrhenius-like concentration-dependence of the relaxation times near the glass transition. The smoother colloids do not show as much orientational correlation except at higher densities leading to fragile behavior. We therefore propose that these materials are an ideal model to study the physical properties of the glass transition.

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Impact of the Distributions of Core Size and Grafting Density on the Self-Assembly of Polymer Grafted Nanoparticles

Bachhar, Nirmalya; Jiao, Yang; Asai, Makoto; Akcora, Pinar; Bandyopadhyaya, Rajdip; Kumar, Sanat

Macromolecules (American Chemical Society)  50 ( 19 ) 7730 - 7738 2017.09

Research paper (scientific journal), Joint Work, Accepted

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Polymer-Grafted Nanoparticle Membranes with Controllable Free-Volume

Connor Bilchak, Eileen Buenning, Makoto Asai, Kai Zhang, Christopher Durning, Sanat Kumar, Yucheng Huang, Brian Benicewicz, David Gidley, Shiwang Cheng, Alexei Sokolov, Matteo Minelli, Ferruccio DoghieriASAI Makoto

Macromolecules (American Chemical Society)  50 ( 18 ) 7111 - 7120 2017.09

Research paper (scientific journal), Joint Work, Accepted

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Role of Grafting Mechanism on the Polymer Coverage and Self-Assembly of Hairy Nanoparticles

ASAI MakotoZHAO DanKUMAR K Sanat

ACS NANO (American Chemical Society)  11 ( 7 ) 7028 - 7035 2017.06

Research paper (scientific journal), Joint Work, Accepted

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Supercoiling transformation of chemical gels

Asai, Makoto, Katashima, Takuya, Sakai, Takamasa, Shibayama, Mitsuhiro

SOFT MATTER 11 ( 36 ) 7101 - 7108 2015

Research paper (scientific journal), Joint Work,  ISSN  1744-683X

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Quantitative analogy between polymer-grafted nanoparticles and patchy particles

Asai, Makoto, Cacciuto, Angelo, Kumar, Sanat K.

SOFT MATTER 11 ( 4 ) 793 - 797 2015

Research paper (scientific journal), Joint Work,  ISSN  1744-683X

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Mechanical properties of tetra-PEG gels with supercoiled network structure

Katashima, Takuya, Asai, Makoto, Urayama, Kenji, Chung, Ung-il, Sakai, Takamasa

JOURNAL OF CHEMICAL PHYSICS 140 ( 7 ) 4177 - 4185 2014.02

Research paper (scientific journal), Joint Work,  ISSN  0021-9606

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A computer simulation of the networked structure of a hydrogel prepared from a tetra-armed star pre-polymer

Takagi, Kaihei, Murayama, Shuhei, Sakai, Takamasa, Asai, Makoto, Santa, Tomofumi, Kato, Masaru

SOFT MATTER 10 ( 20 ) 3553 - 3559 2014

Research paper (scientific journal), Joint Work,  ISSN  1744-683X

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Correlation between Local and Global Inhomogeneities of Chemical Gels

Asai, Makoto, Katashima, Takuya, Chung, Ung-il, Sakai, Takamasa, Shibayama, Mitsuhiro

MACROMOLECULES 46 ( 24 ) 9772 - 9781 2013.12

Research paper (scientific journal), Joint Work,  ISSN  0024-9297

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Mechanical properties of a polymer network of Tetra-PEG gel

Sugimura, Asumi, Asai, Makoto, Matsunaga, Takuro, Akagi, Yuki, Sakai, Takamasa, Noguchi, Hiroshi, Shibayama, Mitsuhiro

POLYMER JOURNAL 45 ( 3 ) 300 - 306 2013.03

Research paper (scientific journal), Joint Work,  ISSN  0032-3896

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Poly(styrene)-based graded-index plastic optical fiber for home networks

Akimoto, Yoshihisa, Asai, Makoto, Koike, Kotaro, Makino, Kenji, Koike, Yasuhiro

OPTICS LETTERS 37 ( 11 ) 1853 - 1855 2012.06

Research paper (scientific journal), Joint Work,  ISSN  0146-9592

High-Thermally Stable and High-Bandwidth Graded Index Plastic Optical Fiber for Vehicle Networks

Asai, Makoto, Yamaki, Yasushi, Takahashi, Satoshi, Koike, Yasuhiro

JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS 49 ( 20 ) 1464 - 1469 2011.10

Research paper (scientific journal), Joint Work,  ISSN  0887-6266

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Common Origin of Dynamics Heterogeneity and Cooperatively Rearranging Region in Polymer Melts

Asai, Makoto, Shibayama, Mitsuhiro, Koike, Yasuhiro

MACROMOLECULES 44 ( 16 ) 6615 - 6624 2011.08

Research paper (scientific journal), Joint Work,  ISSN  0024-9297

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High-Bandwidth Graded-Index Plastic Optical Fiber With Low-Attenuation, High-Bending Ability, and High-Thermal Stability for Home-Networks

Asai, Makoto, Inuzuka, Yukari, Koike, Kotaro, Takahashi, Satoshi, Koike, Yasuhiro

JOURNAL OF LIGHTWAVE TECHNOLOGY 29 ( 11 ) 1620 - 1626 2011.06

Research paper (scientific journal), Joint Work,  ISSN  0733-8724

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Methodological Approach To Control the Refractive Index Profile of Graded-Index Polymer Optical Fiber

Asai, Makoto, Mukawa, Yoshiki, Takahashi, Satoshi, Koike, Yasuhiro

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 50 ( 7 ) 3895 - 3899 2011.04

Research paper (scientific journal), Joint Work,  ISSN  0888-5885

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Effects of Rotation of Benzene Rings on Diffusion of Solvents in Polymer Melts

Asai, Makoto, Awata, Megumi, Koike, Yasuhiro

INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH 50 ( 6 ) 3280 - 3286 2011.03

Research paper (scientific journal), Joint Work,  ISSN  0888-5885

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Novel Dopant for Graded-Index Polymer Optical Fiber with High-Thermal Stability

Yamaki, Yasushi, Asai, Makoto, Takahashi, Satoshi, Koike, Yasuhiro

APPLIED PHYSICS EXPRESS 3 ( 7 ) 1853 - 1855 2010

Research paper (scientific journal), Joint Work,  ISSN  1882-0778

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The future of plastic optical fiber

Koike, Yasuhiro, Asai, Makoto

NPG ASIA MATERIALS 1 ( 1 ) 22 - 28 2009.10

Research paper (scientific journal), Joint Work,  ISSN  1884-4049

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