Quantitative Structure Analysis of a Near-Ideal Polymer Network with Deuterium Label by Small-Angle Neutron Scattering

Ohira, Masashi; Tsuji, Yui; Watanabe, Nobuyuki; Morishima, Ken; Gilbert, Elliot P.; Li, Xiang; Shibayama, Mitsuhiro

doi:10.1021/acs.macromol.9b02695

Cited by 9 publications

(11 citation statements)

References 41 publications

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“…No scattering arising from the chains between HBSP junction points is observed, although they have the same contrast as the occluded PAAm chains around the HBSPs. [ 17 ] This seeming anomalism provides very helpful clues for the interpretation of SANS results. The scattering intensity is roughly proportional to the sixth power of characteristic dimension.…”

Section: Resultsmentioning

confidence: 99%

Hysteresis‐Free Nanoparticle‐Reinforced Hydrogels

et al. 2022

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The elastic storage and release of mechanical energy has been key to many developments throughout the history of mankind. Resilience, absent hysteresis, has been an elusive goal to achieve, particularly at large deformations. Using a low‐crosslink‐density polyacrylamide hydrogel at 96% water content having hyperbranched silica nanoparticles (HBSPs) as the major junction points, a hysteresis‐free material is realized. The fatigue‐free characteristic of these composite hydrogels is evidenced by the invariance of the stress–strain curves at strain ratios of 4, even after 5000 cycles. At a strain ratio of 7, only a 1.3% hysteresis is observed. A markedly increased strain‐ratio‐at‐break of 11.5 is observed. The unique attributes of these resilient hydrogels are manifested in the high‐fidelity detection of dynamic deformations under cyclic loading over a broad range of frequencies, difficult to achieve with other materials.

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Section: Resultsmentioning

confidence: 99%

Hysteresis‐Free Nanoparticle‐Reinforced Hydrogels

et al. 2022

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“…Representative SANS patterns obtained for gels typically lack peaks corresponding to strong correlations between strands or junctions due to the lack of long-range order and the amorphous character of the network (Figure ). − Although it should be noted that scattering curves from charged gels typically do have a feature called the ”polyelectrolyte peak”, which corresponds to the correlation length ξ resulting from the like-charge repulsion of neighboring charged strands, − SANS curves are usually fit with physical models to extrapolate structural parameters, similar to other techniques discussed in this review. Broadly, the high- q region characterizes polymer chains and the low- q region highlights larger length-scale network inhomogeneities.…”

Section: Network Structurementioning

confidence: 99%

Molecular Characterization of Polymer Networks

et al. 2021

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Polymer networks are complex systems consisting of molecular components. Whereas the properties of the individual components are typically well understood by most chemists, translating that chemical insight into polymer networks themselves is limited by the statistical and poorly defined nature of network structures. As a result, it is challenging, if not currently impossible, to extrapolate from the molecular behavior of components to the full range of performance and properties of the entire polymer network. Polymer networks therefore present an unrealized, important, and interdisciplinary opportunity to exert molecular-level, chemical control on material macroscopic properties. A barrier to sophisticated molecular approaches to polymer networks is that the techniques for characterizing the molecular structure of networks are often unfamiliar to many scientists. Here, we present a critical overview of the current characterization techniques available to understand the relation between the molecular properties and the resulting performance and behavior of polymer networks, in the absence of added fillers. We highlight the methods available to characterize the chemistry and molecular-level properties of individual polymer strands and junctions, the gelation process by which strands form networks, the structure of the resulting network, and the dynamics and mechanics of the final material. The purpose is not to serve as a detailed manual for conducting these measurements but rather to unify the underlying principles, point out remaining challenges, and provide a concise overview by which chemists can plan characterization strategies that suit their research objectives. Because polymer networks cannot often be sufficiently characterized with a single method, strategic combinations of multiple techniques are typically required for their molecular characterization.

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“…In addition, the same temperature dependence between the gel and the monosequence profiles suggest that the change in the peak height was irrelevant to the sol–gel transition. By fitting the scattering profiles with a model function for star block copolymers under contrast‐matched conditions [ 53 ] (Figure 3a,b and Section S4.2, Supporting Information), we found that the difference in the peak height was attributed to the changes in the energy interaction between the PEG polymers and the water molecules at different temperatures. The estimated energy interaction parameters (χ) were displayed as a function of temperature (Figure 3c and Figure S8, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Star‐Polymer–DNA Gels Showing Highly Predictable and Tunable Mechanical Responses

et al. 2022

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Dynamically crosslinked gels are appealing materials for applications that require timedependent mechanical responses. DNA duplexes are ideal crosslinkers for building such gels because of their excellent sequence addressability and flexible tunability in bond energy.However, the mechanical responses of most DNA gels are complicated and unpredictable despite the high potential of DNA. Here, we demonstrate a DNA gel with a highly homogeneous gel network and well-predictable mechanical behaviors by using a pair of starpolymer-DNA precursors with presimulated DNA sequences showing the two-state transition.The melting curve analysis of the DNA gels reveals the good correspondence between the thermodynamic potentials of the DNA crosslinkers and the presimulated values by DNA calculators. Stress-relaxation tests and dissociation kinetics measurements show that the macroscopic relaxation time of the DNA gels is approximately equal to the lifetime of the DNA crosslinkers over four orders of magnitude from 0.1-2,000 sec. Furthermore, a series of durability tests find the DNA gels are hysteresis-less and self-healable after the applications of repeated temperature and mechanical stimuli. These results demonstrate the great potential of star-polymer-DNA precursors for building gels with predictable and tunable viscoelastic properties, suitable for applications such as stress-response extracellular matrices, injectable solids, and soft robotics.

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Quantitative Structure Analysis of a Near-Ideal Polymer Network with Deuterium Label by Small-Angle Neutron Scattering

Cited by 9 publications

References 41 publications

Hysteresis‐Free Nanoparticle‐Reinforced Hydrogels

Hysteresis‐Free Nanoparticle‐Reinforced Hydrogels

Molecular Characterization of Polymer Networks

Star‐Polymer–DNA Gels Showing Highly Predictable and Tunable Mechanical Responses

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