We elucidate why the anomalous high strength of double network gels is obtained when second polymerized without any cross-linkers. have synthesized truly independent-DN (named "t-DN" gels), which do not covalent bonds between first and networks, showed that t-DN cannot be toughened by un-cross-linked network. It means usual DN cross-linker actually achieved interconnection two networks through (so were named "c-DN" gels). Further, we found become stronger than c-DN loosely cross-linked. As a...

The fracture energy G of double network (DN) gels, consisting poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) as the first and poly(acrylamide) (PAAm) second network, was measured by tearing test a function crack velocity V. following results were obtained: (i) ranges from 102 to∼103 J/m2, which is 100−1000 times larger than that normal PAAm gels (100 J/m2) or PAMPS (10-1 with similar polymer concentrations to DN gels. (ii) shows weak dependence on (iii) at given value V increases...

ADVERTISEMENT RETURN TO ISSUECommunication to the...Communication the EditorNEXTNecking Phenomenon of Double-Network GelsYang-Ho Na, Yoshimi Tanaka, Yasunori Kawauchi, Hidemitsu Furukawa, Takashi Sumiyoshi, Jian Ping Gong, and Yoshihito OsadaView Author Information Graduate School Science, Creative Research Initiative "SOUSEI", Engineering, Hokkaido University, Sapporo 060-810, Japan, SORST, JST, Japan Cite this: Macromolecules 2006, 39, 14, 4641–4645Publication Date (Web):June 16,...

The mechanical strength of double network (DN) gels consisting highly cross-linked poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) as the first component and linear polyacrylamide (PAAm) second has been investigated by varying molecular weight polymer PAAm, Mw. experimental results reveal that, for toughening DN gels, (1) Mw is one dominant parameters; (2) there a critical value = 106 remarkable enhancement; (3) fracture energy with larger than reaches high 103 J/m2. By plotting...

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication the EditorNEXTDirect Observation of Damage Zone around Crack Tips in Double-Network GelsQiu Ming Yu, Yoshimi Tanaka, Hidemitsu Furukawa, Takayuki Kurokawa, and Jian Ping Gong*View Author Information Department Biological Sciences, Graduate School Science, Hokkaido University, N10W8, Sapporo 060-0810, Japan*Corresponding author: Fax 81-11-706-2635; e-mail [email protected]Cite this: Macromolecules 2009, 42, 12,...

The double network (DN) gels, composed of a minor component, chemically cross-linked polyelectrolyte (first network), and the major one, linear neutral polymer (second exhibit anomalously high mechanical strengths. In this study, adopting concentration second as experimental parameter, we investigate relation between strength dynamics fluctuation. former is measured by compression tearing tests; latter special dynamic light scattering technique (called SMILS) suitable for gels. enhanced when...

We present a phenomenological model for anomalously high fracture energy of double-network (DN) gels, which consist substantially cross-linked polyelectrolyte gel (first network) and quite poorly neutral polymer (second penetrating into the first network (Gong J. P., Katsuyama Y., Kurokawa T. Osada Adv. Mater., 15 (2003) 1155). The assumes that material locally softens around crack tip due to damage network, then extends within softened zone. An order estimation indicates dissipation by...

Limbless crawling is a fundamental form of biological locomotion adopted by wide variety species, including the amoeba, earthworm and snake. An interesting question from biomechanics perspective how limbless crawlers control their flexible bodies in order to realize directional migration. In this paper, we discuss simple but instructive problem peristalsis-like driven elongation–contraction waves that propagate along body axis, process frequently observed slender species such as earthworm....

Robust bonding of a hydrogel in aqueous environment, either to another or solid, is one the major unsolved issues for practical applications hydrogels various fields. Here we report robust between pair sheets, containing over 90 wt% water, by applying double-network (DN) structure. In optimal condition, peeling energy united gel sheets reaches 1200 J m−2, which comparable bulk fracture normal type tough DN gels. This technique also applied form and plastic plates. Furthermore, based on this...

Abstract Double‐network (DN) gels, a type of interpenetrating polymer network (IPN) consisting rigid and flexible components, exhibit two outstanding mechanical behaviors: yielding deformation the entire specimen in tensile tests quite high fracture energy tearing tests. In this study, atomic force microscope (AFM) measurements were conducted on DN gels to determine local Young's moduli immediately below surfaces E f usual molded m , compare modulus with bulk measured before after...

Abstract Introduction of soft filler in a hard body, which is one the common toughening methods polymeric materials, was applied for further robust double network (DN) hydrogels composed poly(2‐acrylamido‐2‐methylpropanesulfonic acid) gels (PAMPS gels) as first component and polyacrylamide (PAAm) second component. The fracture energy DN with void structure (called void‐DN became twice when volume fraction 1–3 vol % diameter much larger than Flory radius PAAm chains. Such induced by wider...

Crawling using muscular waves is observed in many species, including planaria, leeches, nemertea, aplysia, snails, chitons, earthworms and maggots. Contraction or extension propagate along the antero-posterior axis of body as crawler pushes ground substratum backward. However, observation that locomotory can be directed forward backward has attracted much attention over past hundred years. Legged organisms such centipedes millipedes exhibit parallel phenomena; leg tips form density forward....

A CdS/TiO2 photocatalyst modified with a Pd co-catalyst was applied to photocatalytic system for the selective dehydrogenation of benzyl alcohol benzaldehyde high selectivity (>99%) accompanied by formation H2 in aqueous solution under visible-light irradiation.

Journal Article Die Aktin und Myosin ähnliche Proteine im Kalbsthymuszellkern Get access Von TSUYOSHI OHNISHI, OHNISHI *Aus der Abteilung für Physik, Naturwissenschaftliche Fakultat, Universität Nagoya Search for other works by this author on: Oxford Academic PubMed Google Scholar HIROE KAWAMURA, KAWAMURA YOSHIMI TANAKA **und Obermittelschuls Nagakute, Aichi The of Biochemistry, Volume 56, Issue 1, July 1964, Pages 6–15, https://doi.org/10.1093/oxfordjournals.jbchem.a127959 Published: 01...

The slime mould Physarum polycephalum is a giant multinucleated cell exhibiting well-known Ca(2+)-dependent actomyosin contractions of its vein network driving the so-called cytoplasmic shuttle streaming. Its forms both filamentous cortical layer and large fibrils. In order to understand role each structure in locomotory activity, we performed birefringence observations traction force microscopy on excised fragments Physarum. After several hours, these microplasmodia adopt three main...

We investigate a physical characterization of the gradient flow structure variational fracture models for brittle materials: Griffith-type model and an irreversible phase field model. derive by assuming that energy in Griffith's theory is increasing function crack tip velocity. Such velocity dependence typically observed polymers. also prove dissipation identity model, other words, its structure. On hand, derived as unidirectional regularized total energy. have considered time relaxation...

Two novel aplysinopsin-type indole alkaloids, 1 and 2, three known alkaloids were isolated from the marine sponge Hyrtios erecta. These compounds exhibited selective inhibitory activity against neuronal isozyme of nitric oxide synthase (nNOS). Furthermore, new quinolone 7 was also same sponge. The chemical structures these elucidated on basis spectroscopic analysis.

To investigate the mechanical strength of double network (DN) gels in a wide dynamical range, gel solvent was replaced with viscous solvents—ethylene glycol and glycerol—and their mixtures water. The viscosity dependence fracture energy tearing test weak but demonstrated existence characteristic tear velocity for maximum as function viscosity. Fast slow relaxation modes gels' dynamics were simultaneously observed by scanning microscopic light scattering, which reveals that DN-gel structure...