Cross-metathesis of alkenes with vinyl-substituted silsesquioxanes and spherosilicates: a new method for synthesizing highly-functionalized Si/O frameworks

Feher, Frank J.; Soulivong, Daravong; Eklund, Andrew G.; Wyndham, Kevin D.

doi:10.1039/a701996c

Cited by 144 publications

(177 citation statements)

References 16 publications

(8 reference statements)

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“…This geometry was chosen in order to capture general features typical of both traditional filler particles, 1,21 such as a primary carbon black particle, and nanoparticles of polyhedral geometry. 2,[22][23][24][25] To study many such nanoparticles in a dense melt at a reasonable loading would involve O (10 5 ) particles, and hence would require extremely large amounts of CPU time, particularly given the slow dynamics involved in clustering or dispersing of the nanoparticles. While this is feasible for a few select systems, it would severely limit the scope of parameters we can explore.…”

Section: Simulationsmentioning

confidence: 99%

Origin of particle clustering in a simulated polymer nanocomposite and its impact on rheology

Starr

Douglas

Glotzer

2003

The Journal of Chemical Physics

216

183

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Many nanoparticles have short-range interactions relative to their size, and these interactions tend to be ''patchy'' since the interatomic spacing is comparable to the nanoparticle size. For a dispersion of such particles, it is not a priori obvious what mechanism will control the clustering of the nanoparticles, and how the clustering will be affected by tuning various control parameters. To gain insight into these questions, we perform molecular dynamics simulations of polyhedral nanoparticles in a dense bead-spring polymer melt under both quiescent and steady shear conditions. We explore the mechanism that controls nanoparticle clustering and find that the crossover from dispersed to clustered states is consistent with the predictions for equilibrium particle association or equilibrium polymerization, and that the crossover does not appear to match the expectations for first-order phase separation typical for binary mixtures in the region of the phase diagram where we can equilibrate the system. At the same time, we cannot rule out the possibility of phase separation at a lower temperature. Utilizing the existing framework for dynamic clustering transitions offers the possibility of more rationally controlling the dispersion and properties of nanocomposite materials. Finally, we examine how nanocomposite rheology depends on the state of equilibrium clustering. We find that the shear viscosity for dispersed configurations is larger than that for clustered configurations, in contrast to expectations based on macroscopic colloidal dispersions. We explain this result by the alteration of the polymer matrix properties in the vicinity of the nanoparticles. We also show that shear tends to disperse clustered nanoparticle configurations in our system, an effect particularly important for processing.

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Section: Simulationsmentioning

confidence: 99%

Origin of particle clustering in a simulated polymer nanocomposite and its impact on rheology

Starr

Douglas

Glotzer

2003

The Journal of Chemical Physics

216

183

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“…Applications of filled polymers are diverse, ranging from automobile tires and bumpers to the rapidly expanding area of micro-and nano-electronic devices, which are continually challenged by the progressive miniaturization of devices [1,2]. In particular, the growing ability to design customized nano-fillers of arbitrary shape and functionality provides an enormous variety of property modifications by introducing specific heterogeneity at the nanoscale [2][3][4]. However, detailed knowledge of the effects of fillers on a polymer melt at the molecular level is lacking due to the difficulty of directly probing the polymer structure and dynamics in the vicinity of the polymer-filler interface.…”

mentioning

confidence: 99%

Effects of a nanoscopic filler on the structure and dynamics of a simulated polymer melt and the relationship to ultrathin films

2001

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We perform molecular dynamics simulations of an idealized polymer melt surrounding a nanoscopic filler particle to probe the effects of a filler on the local melt structure and dynamics. We show that the glass transition temperature T g of the melt can be shifted to either higher or lower temperatures by appropriately tuning the interactions between polymer and filler. A gradual change of the polymer dynamics approaching the filler surface causes the change in the glass transition. We also find that while the bulk structure of the polymers changes little, the polymers close to the surface tend to be elongated and flattened, independent of the type of interaction we study. Consequently, the dynamics appear strongly influenced by the interactions, while the melt structure is only altered by the geometric constraints imposed by the presence of the filler. Our findings show a strong similarity to those obtained for ultra-thin polymer films (thickness < ∼ 100 nm) suggesting that both ultra-thin films and filled-polymer systems might be understood in the same context.

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“…2(b)]. 27) We have also recently developed facile routes to functionalized T 10 / T 12 cages, such as thiol T 10 [ Fig. 2(c)] and the vinyl T 10 /T 12 compounds described further below.…”

Section: Introductionmentioning

confidence: 99%

“…Decameric T 10 and dodecameric T 12 cages [Figs. 1(b) and 1(c), respectively] are frequently minor products in T 8 cube syntheses, 24)26) and their derivatives often exhibit chemical, thermal, and mechanical properties that parallel those of the T 8 derivatives.…”

Section: Introductionmentioning

confidence: 99%

Facile thiol-ene reactions of vinyl T<sub>10</sub>/T<sub>12</sub> silsesquioxanes for controlled refractive indices for transparent fiber glass reinforced composites

Asuncion

Krug

Abu-Seir

et al. 2015

J. Ceram. Soc. Japan

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A series of thioether-functionalized silsesquioxanes (SQs) was synthesized by radically initiated thiol-ene reactions of vinyl T 10 / T 12 SQ cages with a variety of commercially available thiols. The objectives of this study were to develop model reactions as the basis for using the vinyl T 10/12 compounds as novel crosslinking agents in the synthesis of new types of thiol-ene crosslinked polymers. A second motivation was to develop model compounds with controlled refractive indices and Abbe numbers as possibly modifiers of polymers used for a wide variety of optical and photonic applications. The reactions proceed under mild conditions over 24 h to give thioether SQs in high yields (>90%) and high purity without complex workup. The ease of synthesis coupled with the wide variety and availability of functionalized thiols provides a simple route to elaborating and functionalizing vinyl SQ cages. In addition, the resulting compounds exhibit refractive indices to 1.52 coupled with Abbe numbers to 51 due to the uniquely high electron density provided by the incorporated sulfur atoms, making them ideal compounds for use with optically transparent materials. In addition, cured forms of these compounds provide methods of raising the Abbe number of epoxy resins designed to index match fiberglass with the intent of making transparent fiberglass reinforced composites.

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Cross-metathesis of alkenes with vinyl-substituted silsesquioxanes and spherosilicates: a new method for synthesizing highly-functionalized Si/O frameworks

Cited by 144 publications

References 16 publications

Origin of particle clustering in a simulated polymer nanocomposite and its impact on rheology

Origin of particle clustering in a simulated polymer nanocomposite and its impact on rheology

Effects of a nanoscopic filler on the structure and dynamics of a simulated polymer melt and the relationship to ultrathin films

Facile thiol-ene reactions of vinyl T<sub>10</sub>/T<sub>12</sub> silsesquioxanes for controlled refractive indices for transparent fiber glass reinforced composites

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