Liquids

Malkin, A. Ya.; Isayev, A. I.

doi:10.1016/b978-1-895198-49-2.50008-6

Cited by 5 publications

(5 citation statements)

References 251 publications

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“…This behavior can be explained by considering the effective volume fraction of the different nanogels (Figure ). An effective volume fraction of ∼0.74 is the close packing limiting value for monodispersed hard spheres . When the effective volume fraction is greater than this value, the particles are restricted to volumes smaller than their dilute solution equilibrium swelling volumes .…”

Section: Discussionmentioning

confidence: 99%

Understanding the Phase and Morphological Behavior of Dispersions of Synergistic Dual-Stimuli-Responsive Poly(N-isopropylacrylamide) Nanogels

et al. 2019

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This work represents a detailed investigation into the phase and morphological behavior of synergistic dual-stimuli-responsive poly(N-isopropylacrylamide) nanogels, a material that is of considerable interest as a matrix for in situ forming implants. Nanogels were synthesized with four different diameters (65, 160, 310, and 450 nm) as monodispersed particles. These different samples were then prepared and characterized as both dilute (0.1 wt %) and concentrated dispersions (2–22 wt %). In the dilute form, all of the nanogels had the same response to the triggers of the physiological temperature and ionic strength. In water, the nanogels would deswell when heated above 32 °C, while they would aggregate if heated above this temperature at the physiological ionic strength. In the concentrated form, the nanogels exhibited a wide range of morphological changes, with liquid, swollen gel, shrunken gel, and aggregate structures all possible. The occurrence of these structures was dependent on many factors such as the temperature, ionic strength of the solvent, size and ζ-potential of the nanogel, and dispersion concentration. We explored these factors in detail with techniques such as visual studies, rheology, effective volume fraction, and shape factor measurement. The different-sized nanogels displayed differing phase and morphological behavior, but generally higher concentrations of the nanogels (>7 wt %) yielded gels in water with the transitions depending on the temperature. The smallest nanogel (65 nm diameter) exhibited the most unique behavior; it did not form a swollen gel at any concentration tested. Shape factor measurement for the nanogel samples showed that two of the larger three samples (160 and 310 nm) had core–shell structures with denser core cross-linking, while the smallest nanogel sample displayed a homogeneous cross-linked structure. We hypothesize that the smallest nanogels are able to undergo more extensive interpenetration compared to the larger nanogels, which meant that the smallest nanogel was not able to form a swollen gel. In the presence of salt at 12 wt %, all of the nanogels formed aggregates when heated above 35 °C due to the screening of the electrostatic stabilization by the salt. This work revealed unique behavior of the smallest nanogel with a homogeneous cross-linked structure; its phase and morphological behavior were unlike a particle dispersion, rather these were more similar to those of a branched polymer solution. In total, these findings can be used to provide information about the design of poly(N-isopropylacrylamide) nanogel dispersions for different applications where highly specific spatiotemporal control of morphology is required, for example, in the formation of in situ forming implants or for pore blocking behavior.

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Section: Discussionmentioning

confidence: 99%

Understanding the Phase and Morphological Behavior of Dispersions of Synergistic Dual-Stimuli-Responsive Poly(N-isopropylacrylamide) Nanogels

et al. 2019

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“…PME presents typical behavior of pseudoplastic fluid with the reduced viscosity as the increase of shear rate. This is induced by the release of entanglements between molecular chains under higher shear rate, reducing the viscosity . Also, the viscosity of PME significantly decreases as the temperature enhances from 30 to 90 °C.…”

Section: Resultsmentioning

confidence: 99%

“…This is induced by the release of entanglements between molecular chains under higher shear rate, reducing the viscosity. 44 Also, the viscosity of PME significantly decreases as the temperature enhances from 30 to 90 °C. The resulting polymer was further characterized by DSC and TGA (see Figures S9 and S10).…”

Section: ■ Introductionmentioning

confidence: 97%

Fishbone-Like Polymer from Green Cationic Polymerization of Methyl Eleostearate as Biobased Nontoxic PVC Plasticizer

Feng

Chu

Man

et al. 2019

ACS Sustainable Chem. Eng.

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Herein, fishbone-like poly(methyl eleostearate) (PME) plasticizer with high biobased content of near 90% was developed for the production of flexible poly(vinyl chloride) (PVC) by the green cationic polymerization of biobased monomer methyl eleostearate (ME) using renewable coconut oil as solvent, rather than the traditional alkyl halides with toxicity and volatility. The microstructure of PME was investigated by multiple technologies, and the results show that the favored microstructure of PME is the 9,10-unit because of the lower surface electrostatic potential and average local ionization energy near the double bond at C9 and C10. The acute toxicity test of PME shows that it is biologically safe and nontoxic. The effect of content of PME and the commercial plasticizer bis(2-ethylhexyl) phthalate (DOP) on the performance of plasticized PVC was investigated. When the weight ratio of PME and DOP is fixed at 1:1, PVC film presents higher stretchability (604.7% vs 309.1%) and enhanced strength (21.0 MPa vs 11.0 MPa) compared with PVC plasticized with DOP. A possible mechanism related to chain entanglements and dipole−dipole interaction is proposed. Further, as DOP is substituted with PME, PVC films show improved migration resistance with the weight loss being more than 75% lower after leaching in petroleum ether and olive oil.

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“…The final deposition pattern that forms is the result of a complex interplay between the evaporation-driven capillary flow inside the droplet 23,24 that transports the collagen fibers towards the contact line, the motion and/ or pinning of the contact line 13,25 , the interaction between the collagen and the substrate 26 and the solution rheology 27 . At the periphery of the stain, a pattern of radially-oriented v-shaped stripes was observed.…”

Section: Discussionmentioning

confidence: 99%

Self-agglomerated collagen patterns govern cell behaviour

Eren

Wilting

et al. 2021

Sci Rep

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Reciprocity between cells and their surrounding extracellular matrix is one of the main drivers for cellular function and, in turn, matrix maintenance and remodelling. Unravelling how cells respond to their environment is key in understanding mechanisms of health and disease. In all these examples, matrix anisotropy is an important element, since it can alter the cell shape and fate. In this work, the objective is to develop and exploit easy-to-produce platforms that can be used to study the cellular response to natural proteins assembled into diverse topographical cues. We demonstrate a robust and simple approach to form collagen substrates with different topographies by evaporating droplets of a collagen solution. Upon evaporation of the collagen solution, a stain of collagen is left behind, composed of three regions with a distinct pattern: an isotropic region, a concentric ring pattern, and a radially oriented region. The formation and size of these regions can be controlled by the evaporation rate of the droplet and initial collagen concentration. The patterns form topographical cues inducing a pattern-specific cell (tenocyte) morphology, density, and proliferation. Rapid and cost-effective production of different self-agglomerated collagen topographies and their interfaces enables further study of the cell shape-phenotype relationship in vitro. Substrate topography and in analogy tissue architecture remains a cue that can and will be used to steer and understand cell function in vitro, which in turn can be applied in vivo, e.g. in optimizing tissue engineering applications.

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Liquids

Cited by 5 publications

References 251 publications

Understanding the Phase and Morphological Behavior of Dispersions of Synergistic Dual-Stimuli-Responsive Poly(N-isopropylacrylamide) Nanogels

Understanding the Phase and Morphological Behavior of Dispersions of Synergistic Dual-Stimuli-Responsive Poly(N-isopropylacrylamide) Nanogels

Fishbone-Like Polymer from Green Cationic Polymerization of Methyl Eleostearate as Biobased Nontoxic PVC Plasticizer

Self-agglomerated collagen patterns govern cell behaviour

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