Morphology and molecular dynamics investigation of PDMS adsorbed on titania nanoparticles: Effects of polymer molecular weight

Klonos, Panagiotis Α.; Dapei, Giorgia; Sulym, Iryna; Zidropoulos, Spilios; Sternik, Dariusz; Deryło–Marczewska, Anna; Borysenko, M.V.; Gun’ko, Vladimir M.; Kyritsis, Apostolos; Pissis, P.

doi:10.1016/j.eurpolymj.2015.11.010

Cited by 62 publications

(124 citation statements)

References 75 publications

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“…Since each of these segments adsorb/desorb effectively independent of each other, there should be no cooperative effects associated with their slow relaxations. It is these two facts, in combination, that we believe are responsible for the Arrhenius dependence that emerges under these larger NP loadings 36 .…”

Section: Resultsmentioning

confidence: 73%

Network dynamics in nanofilled polymers

et al. 2016

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It is well accepted that adding nanoparticles (NPs) to polymer melts can result in significant property improvements. Here we focus on the causes of mechanical reinforcement and present rheological measurements on favourably interacting mixtures of spherical silica NPs and poly(2-vinylpyridine), complemented by several dynamic and structural probes. While the system dynamics are polymer-like with increased friction for low silica loadings, they turn network-like when the mean face-to-face separation between NPs becomes smaller than the entanglement tube diameter. Gel-like dynamics with a Williams–Landel–Ferry temperature dependence then result. This dependence turns particle dominated, that is, Arrhenius-like, when the silica loading increases to ∼31 vol%, namely, when the average nearest distance between NP faces becomes comparable to the polymer's Kuhn length. Our results demonstrate that the flow properties of nanocomposites are complex and can be tuned via changes in filler loading, that is, the character of polymer bridges which ‘tie' NPs together into a network.

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Section: Resultsmentioning

confidence: 73%

Network dynamics in nanofilled polymers

et al. 2016

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“…For the A200 nanocomposites with high ϕ and low M η , a G ”( γ , ϕ ) overshoot appears [Figure (a)] and its intensity increases with increasing ϕ and decreases with increasing M η . This overshoot is possibly related to extra dissipation of mechanical energy arising from friction among FS nanoparticles in the A200 agglomerates that are abundant in the low‐ M η matrix due to low shear force during the compounding process . The overshoot sometimes observed in flocculated gels is attributed to severe nonlinear processes involved in filler structure .…”

Section: Resultsmentioning

confidence: 99%

“…Nanocomposites with lower‐molecular weight matrices exhibit greater reinforcement and stronger nonlinearity . Nevertheless, influences of molecular weight on the interfacial structure and the rheology behavior are far from being understood. Polyethylene oxide (PEO) as a kind of polar polymer is widely used in biomedical and electrochemical materials and it is also used in nanocomposites, for example, with fumed silica (FS) as the filler for preparing shear thickening liquids and improving mechanical properties .…”

Section: Introductionmentioning

confidence: 99%

Rheological behavior of fumed silica filled polyethylene oxide

Zhang

Song

et al. 2019

J Polym Sci B Polym Phys

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Influence of molecular weight of polymer matrix on nanocomposites rheology is not yet well understood. Herein dynamic rheological responses of fumed silica (FS)/polyethylene oxide (PEO) nanocomposites are investigated as a function of viscosity‐averaged molecular weight (Mη) of PEO, volume fraction (ϕ) and surface characteristics (hydrophilic or hydrophobic) of FS. In the nanocomposites, FS does not influence the glass transition and crystallinity of PEO in the mobile PEO phase while the interfacial interactions tend to immobilize a small fraction of PEO chains that could not undergo glass transition. In spite of the common observation that the reinforcement decreases with increasing Mη of PEO and improving hydrophobicity of FS, linear rheological responses are well reproduced by the two‐phase model, revealing the crucial contribution of the non‐Newtonian matrix undergoing microscopic strain amplified by the filler. Furthermore, nonlinear rheological responses of the nanocomposites are collapsed into master curves plotted against local strain of the matrix. Analyzing the nonlinear rheology by Fourier transform and stress waveform methods reveal the dominating contribution of the matrix and the role of strain amplification played by the filler. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 397–405

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“…The analysis of the dielectric spectra is made by using empirical equation of Havriliak and Negami (HN) . In this model, the frequency dependences of the dielectric complex (ε * ) can be described by

ε^{*} (|, ω) = ε_{\infty} + \frac{Δ ε}{{[1 + {(|, i ω τ_{H N})}^{α}]}^{β}}

where Δ ε = ε s − ε ∞ is the dielectric strength, ε s and ε ∞ are the relaxed and unrelaxed values of dielectric constant, the parameters α and β (0 < α, αβ ≤ 1) define the symmetrical and asymmetrical broadening of the loss peak, and τ HN is the characteristic relaxation time. The segmental relaxation of PI and EPI can be excellent fitted using HN equation, as shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

Role of epoxidation on segmental motion of polyisoprene as studied by broadband dielectric spectroscopy

Luo

Gao

et al. 2016

J of Applied Polymer Sci

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In this article, the broadband dielectric spectroscopy (BDS) is used to investigate the relaxation behavior of polyisoprene (PI) epoxidized to various levels and the special consideration is devoted to the effect of epoxidation degree on segmental relaxation. To associate segmental relaxation with molecular structure, several empirical equations are used to fit experimental data. Furthermore, we want to discuss the origin of the change of segmental relaxation. Thermal measurement reveals that glass transition temperature of epoxidized PI (EPI) increase with the increase of epoxidation degrees. The epoxidation modification increases the breadth of the dielectric dispersion. Oxirane groups as steric interference enhance the cooperativity of segmental relaxation process and retard the relaxation process, which results in the increase of coupling parameter. Specifically, Vogel-Fulcher-Tammann equation shows the relationship between correlation length and temperature. These results further illustrate the effect of epoxidation group on segmental motion of PI.

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Morphology and molecular dynamics investigation of PDMS adsorbed on titania nanoparticles: Effects of polymer molecular weight

Cited by 62 publications

References 75 publications

Network dynamics in nanofilled polymers

Network dynamics in nanofilled polymers

Rheological behavior of fumed silica filled polyethylene oxide

Role of epoxidation on segmental motion of polyisoprene as studied by broadband dielectric spectroscopy

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