An unprecedented jump in the viscosity of high-generation carbosilane dendrimer melts

Васильев, В. Г.; Kramarenko, Elena Yu.; Татаринова, Е. А.; Milenin, Sergey A.; Калинина, А. А.; Папков, В. С.; Muzafarov, А. М.

doi:10.1016/j.polymer.2018.05.016

Cited by 34 publications

(32 citation statements)

References 31 publications

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“…Along with single dendrimers in dilute solutions [14,15,16,17,18,19,20,21,22,23], much attention is attracted nowadays to concentrated solutions and melts [24,25,26,27,28,29,30,31,32,33,34], where intermolecular interactions of dendrimer molecules are significant. It is expected that the tree-like molecular morphology of dendrimers would distinguish their behavior from that of conventional linear polymers.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, a number of novel unusual phenomena has recently been observed in dendrimer melts that do not have any strict fundamental description. One such phenomenon is an unprecedented jump in the viscosity of high-generation carbosilane dendrimer melts [31]. It has been found that while low-generation dendrimer melts are Newtonian liquids, high-generation dendrimers demonstrate solid-like behavior.…”

Section: Introductionmentioning

confidence: 99%

“…It has been found that while low-generation dendrimer melts are Newtonian liquids, high-generation dendrimers demonstrate solid-like behavior. The transition between these states is very sharp; it is realized within one generation step (from the fifth to the sixth generation), and it is accompanied by a six-orders-of-magnitude jump of the melt viscosity [31]. The dendrimer specificity also manifests itself in NMR spectra of melts of polybutylcarbosilane dendrimers from the fourth to the sixth generation [32]; in particular, the spectrum of the generation-6 (G6) dendrimers is characterized by a single unresolved broad line in the whole temperature range above the glass transition temperature, which suggests the presence of an anomalous phase state of G6 dendrimers with restricted molecular mobility.…”

Section: Introductionmentioning

confidence: 99%

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A Comparative Study of Intramolecular Mobility of Single Siloxane and Carbosilane Dendrimers via Molecular Dynamics Simulations

et al. 2018

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A comparative analysis of intramolecular dynamics of four types of isolated dendrimers from the fourth to the seventh generations belonging to the siloxane and carbosilane families, differing in spacer length, core functionality, and the type of chemical bonds, has been performed via atomic molecular dynamics simulations. The average radial and angular positions of all Si branching atoms of various topological layers within the dendrimer interior, as well as their variations, have been calculated, and the distributions of the relaxation times of their radial and angular motions have been found. It has been shown that the dendrons of all the dendrimers elongate from the center and decrease in a solid angle with an increasing generation number. The characteristic relaxation times of both angular and radial motions of Si atoms are of the order of a few nanoseconds, and they increase with an increasing generation number and decrease with temperature, with the angular relaxation times being larger than the radial ones. The relaxation times in the carbosilanes are larger than those in the siloxanes. The rotational angle dynamics of the carbosilane dendrimers show that the chain bending is mainly realized via trans-gauche transitions in the Si branching bonds.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Comparative Study of Intramolecular Mobility of Single Siloxane and Carbosilane Dendrimers via Molecular Dynamics Simulations

et al. 2018

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“…Viscosity is the dominant factor among all rheological properties to cause severe effects on polymer melting flow capability in processing and molding. With the continuous development of simulation of molding process and composite polymer processing, it is more necessary to obtain reliable rheological data, especially shear viscosity …”

Section: Introductionmentioning

confidence: 98%

Effects of stick–slip transition on polymer melt apparent shear viscosity measurement

Zhang

Song

Kan

et al. 2019

J of Applied Polymer Sci

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A twin‐bore capillary rheometer is used for the apparent shear viscosity measurement of commercial polyolefin melts based on Ostwald‐de Waele model. The effects of stick–slip transition of linear low‐density polyethylene (LLDPE) and high‐density polyethylene (HDPE) are investigated. The maximum error of apparent shear viscosity calculated by corrected shear rate is 23% when the stick–slip transition occurs. Based on the entanglement‑disentanglement theory, a schematic diagram for shear stress curve containing stick–slip transition is presented to illustrate polymer melt flow in capillary. In this study, the critical stress at the beginning of stick–slip transition at 220 °C is 23.01 kPa higher than that at 190 °C, and why it increases with increasing temperature is discussed with a molecular mechanism in combination with entropy elasticity and entanglement‑disentanglement theory. Through the analysis of ULDPE, PS, EVA, and K‐Resin, it can be found that short branches or side groups are helpful to avoid the stick–slip transition. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48230.

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“…In the past few years, an interest in the study of these dendrimers in bulk has been increasing [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ]. Research was carried out both by experimental methods and by computer simulations.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Silicon-Containing Dendrimers: Effects of Chemical Composition, Structure, and Generation Number

et al. 2021

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We studied the conformational behavior of silicon-containing dendrimers during their adsorption onto a flat impenetrable surface by molecular dynamics (MD) simulations. Four homologous series of dendrimers from the 4th up to the 7th generations were modeled, namely, two types of carbosilane dendrimers differing by the functionality of the core Si atom and two types of siloxane dendrimers with different lengths of the spacers. Comparative analysis of the fractions of adsorbed atoms belonging to various structural layers within dendrimers as well as density profiles allowed us to elucidate not only some general trends but also the effects determined by dendrimer specificity. In particular, it was found that in contrast to the carbosilane dendrimers interacting with the adsorbing surface mainly by their peripheral layers, the siloxane dendrimers with the longer –O–Si(CH3)2–O spacers expose atoms from their interior to the surface spreading out on it. These findings are important for the design of functional materials on the basis of silicon-containing dendrimers.

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An unprecedented jump in the viscosity of high-generation carbosilane dendrimer melts

Cited by 34 publications

References 31 publications

A Comparative Study of Intramolecular Mobility of Single Siloxane and Carbosilane Dendrimers via Molecular Dynamics Simulations

A Comparative Study of Intramolecular Mobility of Single Siloxane and Carbosilane Dendrimers via Molecular Dynamics Simulations

Effects of stick–slip transition on polymer melt apparent shear viscosity measurement

Adsorption of Silicon-Containing Dendrimers: Effects of Chemical Composition, Structure, and Generation Number

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