| POLYMERS Vol.72 No.9 |
| >> Japanese | >> English |
COVER STORY
Soft×Polymer! |
| COVER STORY: Highlight Reviews |
| Crack Growth Dynamics of Soft Materials | Thanh Tam MAI, Katsuhiko TSUNODA, Kenji URAYAMA |
| <Abstract> This review describes the recent progress in the research on the crack growth dynamics in soft materials. The soft materials such as elastomers exhibit interesting features in the crack growth dynamics, which result from their high deformability, viscoelasticity and strain crystallizability. Keywords: Crack / Fracture / Elastomer / Rubber / Soft Material |
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| Understanding Microscopic Dynamics of Soft Materials by Computational Chemistry | Shunsuke SATO, Go WATANABE |
| <Abstract> For understanding the structure and functions of soft materials, it is of much importance to reveal their dynamics at the molecular scale. Molecular dynamics (MD) simulation, which is one of the useful computational chemistry tools, enables us to estimate the stability of the supramolecular assembly by using the free energy. In this review, we show the overview of calculating the free energy with MD simulations and recent studies and also discuss how to help the creation of supramolecular materials. Keywords: Soft Materials / Supramolecular Assembly / Computational Chemistry / Molecular Dynamics Simulation / Free Energy Calculations / Umbrella Sampling |
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| Prospect of Soft Materials Prepared from Green Resources | Seiichi KAWAHARA |
| <Abstract> Green resources obtained from plants, which may play an important role in a 21st century chemistry, has a potential to prepare various soft materials to realize carbon-neutral society. The green resources include not only natural rubber and naturally occurring cis-1,4-polyisoprene but also ethylene, propylene, butadiene, isoprene and isobutene, which are produced from glucose photo-synthesized with carbon dioxide and water. Natural rubber and cis-1,4-polyisoprene are used to produce a wide variety of products useful for daily life, while ethylene, propylene, butadiene, isoprene and isobutene are used to prepare general purpose (GP) rubbers, i.e., ethylene-propylene-diene monomer rubber (EPDM), butadiene rubber (BR), isoprene rubber (IR) and butyl rubber (IIR). In the present article, current status and future prospects of rubbery soft materials are described for natural rubber, naturally occurring cis-1,4-polyisoprene and the GP rubbers obtained from the green resources. Rubbers prepared from dialkyl itaconate with isoprene and butadiene are also described as a novel rubber that leads to the next generation materials. Keywords: Green Resources / Natural Rubber / Guayule Rubber / Isoprene Rubber / Butadiene Rubber / Butyl Rubber / EPDM / Island-Nanomatrix Structure |
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| COVER STORY: Topics and Products |
| Control of Fluidity of Gels by Double-Stranded DNA | Masashi OHIRA, Xiang LI |
| <Abstract> Hydrogel, a soft material made of 3D cross-linked polymers in water, resembles biological tissue due to its high water content and viscoelastic behavior. Recent research indicates that controlling viscoelastic properties is crucial for successful medical applications. We focus on the fact that the double-stranded DNA (dsDNA) dislocation rate can be regulated by its base sequence under physiological conditions and have fabricated the new DNA gels (SP-DNA gel). SP-DNA gel is fabricated using the recently proven star polymer strategy and a pair of DNA sequences that exhibit a two-state transition as dynamic cross-linkers. The thermodynamic behavior of DNA in SP-DNA corresponds well to the simulated result, indicating that the thermo-stability of SP-DNA gels can be designed based on calculations. Furthermore, viscoelasticity measurements and dsDNA dissociation kinetics showed that the macroscopic stress relaxation time of the SP-DNA gel agreed with the dsDNA dissociation time over a wide time range, suggesting that the viscoelasticity of the hydrogel can be controlled by adjusting the dsDNA dissociation time. Keywords: Hydrogel / Visoclestisy / DNA |
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| Biomass Conversion of Plasticizer Contributing to Soft Materials | Shoki YOSHICHIKA |
| <Abstract> Plasticizers are added to plastics to make them more flexible, and many of them are phthalate esters derived from petrochemicals. It is believed that if these can be replaced with plasticizers made from renewable resources, the environmental impact could be greatly reduced. In this report, we will introduce the Greencizer BZ series, a plasticizer made from renewable materials that offers equal or better performance than phthalate esters. Keywords: Circular Economy / Naturally-Derived / Plasticizer / Polyvinyl Chloride |
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| Microphase Separation of Double Hydrophilic Block Copolymer Aqueous Solutions | Yuji HIGAKI |
| <Abstract> Phase separation of macromolecules in aqueous media has reignited the interest of scientists across various disciplines over the past decade. Double hydrophilic block copolymers integrating zwitterionic polymer chain exhibited unique phase separation characteristics in the aqueous solutions. The morphology transformed depending on the polymer concentration due to the interfacial curvature modulation through the volume expansion of one phase due to the selective water partitioning. The microphase separation of double hydrophilic block copolymers was also induced by cononsolvency of a zwitterionic polymer. The lyotropic mesophase of double hydrophilic block copolymers is a unique molecular compartment for hydrophilic molecules. Keywords: Microphase Separation / Block Copolymer / Zwitterionic Polymer / Water |
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| Polymer Science and I: A Personal Account |
| An Encouragement of Getting a Ph.D. while Working | Ryoyu HIFUMI |
| <Abstract> In this column, I would like to share my experiences and difficulties in getting a Ph.D. while working full-time in a company. I hope this column will be helpful to working professionals with a master's degree who are interested in a Ph.D. degree. |
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| Front-Line Polymer Science |
| Practical Synthesis of Structurally Controlled Dendritic Hyperbranched Polymer by Reversible Deactivation Radical Polymerization | Shigeru YAMAGO, Yuhan JIANG |
| <Abstract> Recent development in the synthesis of structurally controlled hyperbranched polymers (HBPs) by organotellurium-mediated radical polymerization (TERP) is introduced. Although structural control and practicality in the synthesis of HBPs have been a trade-off, we have successfully solved this issue by designing a new branch-inducing monomer called evolmer and copolymerizing it with conventional monomers under TERP. Branch numbers and density were easily controlled by changing the amount of a TERP chain transfer agent (CTA), evolmer, and conventional monomers. Furthermore, branch structures could also be controlled by using multivalent CTAs and macro-CTAs. In addition, physical properties, such as intrinsic viscosity, could also be finely tuned by the branch structure. The design principle of this method and its practical effects are discussed in this review. Keywords: Dendritimer / Hyperbranched Polymer / Highly Branched Polymers / TERP / Reversible Deactivation Radical Polymerization / Evolmer / Precision Polymer Synthesis |
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