The free-radical mechanism of the SiO bond fracture in polysiloxanes as a result of mechanical disintegration

Dubinskaya, A.M.; Nikul'shin, S.F.; Rabkina, A. Yu.; Zavin, B. G.

doi:10.1016/0032-3950(80)90086-6

Cited by 5 publications

(1 citation statement)

References 11 publications

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“…A study of mechanical treatment of mixtures of polymers with monomers in a vibratory mill provided experimental data on the addition of free radicals to C=C bonds. 24 Under the same conditions, carbon-centred and silyl macroradicals add to benzene and its derivatives to give radicals of the cyclohexadienyl type, 63,64 which occurs on mechanical treatment of the initial compounds in a vibrational mill, has been studied in the 80 ± 143 K temperature range. 24 At 80 K, the reaction does not proceed, and at 113 ± 143 K the dependence of the rate constant on the temperature obeys the Arrhenius equation.…”

Section: Additionmentioning

confidence: 99%

Transformations of organic compounds under the action of mechanical stress

Dubinskaya¹

1999

Russ. Chem. Rev.

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Section: Additionmentioning

confidence: 99%

Transformations of organic compounds under the action of mechanical stress

Dubinskaya¹

1999

Russ. Chem. Rev.

View full text Add to dashboard Cite

Mechanoradicals Created in “Polymeric Sponges” Drive Reactions in Aqueous Media

Baytekin

Grzybowski

2012

Angewandte Chemie

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The study of mechanochemical phenomena in polymers dates back to the work of Staudinger, [1] who attributed the reduction in the molecular weight of polymers under mastication to the mechanical rupture of the constituent macromolecules. Subsequent studies have established that these and other related effects [2] are a result of the homolytic cleavage of covalent bonds and creation of radicals within stressed polymers. [3] Technologically, mechanochemical treatment has been used to adjust the rheological properties of rubbers, [4] to degrade biopolymers, such as starch, to desired molecular weights, [5] to dehalogenate hazardous polymer contaminants, [6] to polymerize or copolymerize through vigorous milling and/or grinding, and it has also been used as the basis of mechanochromism. [7] Yet, these applications remain scarce and specialized, and in virtually all everyday systems where polymers are subject to mechanical stresses, for example, in the tires of road vehicles, the soles of walking shoes, and so on, the chemical energy of homolytically broken bonds is not being harnessed in any purposeful way. Herein, we show how a significant fraction of this ubiquitous, and in some sense "free" (for otherwise not used), energy can be retrieved if the polymers that are being deformed are in contact with water. Under these conditions, the mechanoradicals that are created within the polymer migrate to the polymer/water interface, at which they produce H 2 O 2 , which can then drive several types of chemical processes, such as nanoparticle synthesis, dye bleaching, or fluorescence. The amount of H 2 O 2 that is produced scales with the interfacial area and is in the order of tens of mg m À2 for 1 J of mechanical energy input, and the overall efficiency of the mechanical-tochemical energy conversion is, depending on the polymer used, from approximately 7 % up to a remarkable 30 % for soft, "spongy" polymers. Deformable polymer "sponges" that drive aqueous-phase radical reactions can be construed as solid-state chemical reagents that convert mechanical energy into chemical energy in a "clean", environmentally friendly fashion. On the other hand, the fact that polymers under stress produce potentially harmful [8] free radicals might raise concerns about the safety of polymer-based medical implants. [9] We used the flexible polymers poly(dimethylsiloxane) (PDMS, Dow Corning, Sylgard 184), Tygon (Saint-Gobain Corp. #R-3603), and poly(vinyl chloride) (PVC, VWR, #60985-534), all of which gave qualitatively similar results. Typically, hollow polymer tubes (inner diameter 0.6-0.8 cm, outer diameter 1.5 cm, height ca. 7.5 cm) were filled with water or an aqueous solution of a desired reagent, and were compressed mechanically with strains of up to 40 % (Figure 1 a). In all cases, the deformations were nondestructive and reversible at the macroscopic level, as shown by the forcedisplacement curves of the squeezed polymers not changing over many compression/release cycles (see Figure S10 in the Supporting Information). Measurements ...

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Mechanoradicals Created in “Polymeric Sponges” Drive Reactions in Aqueous Media

Baytekin

Grzybowski

2012

Angew Chem Int Ed

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The free-radical mechanism of the SiO bond fracture in polysiloxanes as a result of mechanical disintegration

Cited by 5 publications

References 11 publications

Transformations of organic compounds under the action of mechanical stress

Transformations of organic compounds under the action of mechanical stress

Mechanoradicals Created in “Polymeric Sponges” Drive Reactions in Aqueous Media

Mechanoradicals Created in “Polymeric Sponges” Drive Reactions in Aqueous Media

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