SANS Study on Critical Polymer Clusters of Tetra-Functional Polymers

Li, Xiang; Hirosawa, Kazu; Sakai, Takamasa; Gilbert, Elliot P.; Shibayama, Mitsuhiro

doi:10.1021/acs.macromol.7b00528

Cited by 15 publications

(29 citation statements)

References 28 publications

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“…We have presented experimental characterisation of two DNA hydrogels resulting from the thermoreversible association of DNA-made nanoparticles with functionality four. The possibility to exploit base-pair selectivity and the self-assembly properties of DNA sequences of different length permitted us to tune the viscoelastic properties as desired, providing significant design flexibility compared to tetravalent star polymers 50–52. Specifically, we have compared a system that gels on cooling (the NS system), with a system that gels both on cooling, when starting from high T , and on heating, when starting from low T (the RG system).…”

Section: Discussionmentioning

confidence: 99%

Microrheology of DNA hydrogel gelling and melting on cooling

et al. 2018

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We present systematic characterisation by means of dynamic light scattering and particle tracking techniques of the viscosity and of the linear viscoelastic moduli, G'(ω) and G''(ω), for two different DNA hydrogels. These thermoreversible systems are composed of tetravalent DNA-made nanostars whose sticky sequence is designed to provide controlled interparticle bonding. While the first system forms a gel on cooling, the second one has been programmed to behave as a re-entrant gel, turning again to a fluid solution at low temperature. The frequency-dependent viscous and storage moduli and the viscosity reveal the different viscoelastic behavior of the two DNA hydrogels. Our results show how little variations in the design of the DNA sequences allow tuning of the mechanical response of these biocompatible all-DNA materials.

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Section: Discussionmentioning

confidence: 99%

Microrheology of DNA hydrogel gelling and melting on cooling

et al. 2018

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“…Health and biomedicine. Shibayama and co-workers from the University of Tokyo have conducted extensive SANS studies to examine the structure of poly(ethylene glycol) (PEG)-based gels (Li et al, 2017;Nakagawa et al, 2017;Hiroi et al, 2016). Based on tetra-armed PEG polymers, with either thiol or maleimide termini, a synthesis strategy was developed to produce a new class of hydrogel with extremely low swelling pressure.…”

Section: Figure 10mentioning

confidence: 99%

QUOKKA, the pinhole small-angle neutron scattering instrument at the OPAL Research Reactor, Australia: design, performance, operation and scientific highlights

et al. 2018

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1 This article will form part of a virtual special issue on advanced neutron scattering instrumentation, marking the 50th anniversary of the journal.QUOKKA is a 40 m pinhole small-angle neutron scattering instrument in routine user operation at the OPAL research reactor at the Australian Nuclear Science and Technology Organisation. Operating with a neutron velocity selector enabling variable wavelength, QUOKKA has an adjustable collimation system providing source-sample distances of up to 20 m. Following the largearea sample position, a two-dimensional 1 m 2 position-sensitive detector measures neutrons scattered from the sample over a secondary flight path of up to 20 m. Also offering incident beam polarization and analysis capability as well as lens focusing optics, QUOKKA has been designed as a general purpose SANS instrument to conduct research across a broad range of scientific disciplines, from structural biology to magnetism. As it has recently generated its first 100 publications through serving the needs of the domestic and international user communities, it is timely to detail a description of its asbuilt design, performance and operation as well as its scientific highlights. Scientific examples presented here reflect the Australian context, as do the industrial applications, many combined with innovative and unique sample environments. research papers J. Appl. Cryst. (2018). 51, 294-314 Kathleen Wood et al. QUOKKA 295 Figure 1 QUOKKA instrument layout. research papers J. Appl. Cryst. (2018). 51, 294-314 Kathleen Wood et al. QUOKKA 297 Figure 3(a) Attenuator wheel. (b) Automatic aperture changer. (c) Sample environment area, showing the extendable bellows on the left and the 20position sample changer on the right. Downstream of the sample changer, the entrance to the detector tank is visible. (d) Beamstop mechanism, with the six beamstops all in the 'in beam' position.research papers J. Appl. Cryst. (2018). 51, 294-314 Kathleen Wood et al. QUOKKA 299 research papers J. Appl. Cryst. (2018). 51, 294-314 Kathleen Wood et al. QUOKKA 301 research papers J. Appl. Cryst. (2018). 51, 294-314 Kathleen Wood et al. QUOKKA 313

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“…Here, I ( q ) is the scattering intensity, and ξc is the correlation length (the size of correlation blob). The details of tetra-PEG gels have been described elsewhere [19,20,21,22,23,24,25,26,27,28]. The above-mentioned polymer networks are symmetric polymer networks consisting of tetra-PEGs with equi-molecular weights and equi-functionality.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Mesh Size in Model Polymer Networks Consisting of Tetra-Arm and Linear Poly(ethylene glycol)s

Tsuji

Shibayama

2018

Gels

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The structure and mechanical properties of model polymer networks consisting of alternating tetra-functional poly(ethylene glycol)s (PEGs) and bis-functional linear PEGs were investigated by dynamic light scattering and rheological measurements. The sizes of the correlation blob (ξc) and the elastic blob (ξel) were obtained from these measurements and compared to the theoretical mesh size, the geometric blob (ξg), calculated by using the tree-like approximation. By fixing the concentration of tetra-PEGs and tuning the molecular weight of linear-PEGs, we systematically compared these blob sizes in two cases: complete network (Case A) and incomplete network (Case B). The correlation blob, ξc, obtained by dynamic light scattering (DLS) was found to obey the well-known concentration dependence for polymer solutions in semidilute regime (ξc~ϕ−3/4) irrespective of the Cases. On the other hand, the G′ was strongly dependent on the Cases: For Case A, G′ was weakly dependent on the molecular weight of linear-PEGs (G′~Mc0.69) while G′ for Case B was a strong increasing function of Mc (G′~Mc1.2). However, both of them are different from the geometric blob (theoretical mesh) of the gel networks. In addition, interesting relationships between G′ and ξc, G′~ξc, G′~ξC−2, were obtained for Cases A and B, respectively.

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SANS Study on Critical Polymer Clusters of Tetra-Functional Polymers

Cited by 15 publications

References 28 publications

Microrheology of DNA hydrogel gelling and melting on cooling

Microrheology of DNA hydrogel gelling and melting on cooling

QUOKKA, the pinhole small-angle neutron scattering instrument at the OPAL Research Reactor, Australia: design, performance, operation and scientific highlights

Evaluation of Mesh Size in Model Polymer Networks Consisting of Tetra-Arm and Linear Poly(ethylene glycol)s

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