Inorganic Polymerization Reactions II. Addition Polymerization

Sowerby, D. Bryan; Audrieth, L. F.

doi:10.1021/ed037p86

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…This technique also provides the osmotic second virial coefficient. The background subtracted intensity scattered by the POA expressed by the Rayleigh ratio (∆R) (to make it independent of the experimental setup) is related to the weight-average molecular weight (〈M〉 w ) by where K is an optical constant: K ) 2π 2 n 2 λ -4 (dn/dc) 2 and 〈B〉 z is the z-average second virial coefficient. The refractive index increment (dn/dc) has been measured with a differential refractometer working at the D lines of sodium (λ ) 589.2 nm).…”

Section: Methodsmentioning

confidence: 99%

“…Soft chemistry routes to solid-state materials are based on inorganic polycondensation reactions. − In the sol−gel processes, for instance, glasses or oxide ceramics are produced by pyrolysis of metalo-organic polycondensates such as polyoxoalkoxides (POAs). Such macromolecular precursors for oxides are obtained through the polycondensation of alkoxides of generic formula M(OR) z , at room temperature and in an organic solvent (M is a cation (Si, Ti, Zr, etc.)…”

Section: Introductionmentioning

confidence: 99%

“…Silicon alkoxide (TMOS, TEOS) polycondensation has been widely studied. , It has provided model systems for experimental work on aggregation and gelation . The formation of POAs from transition metal alkoxides (TMAs) involves both polycondensation and coordination polymerization. − ,, …”

Section: Introductionmentioning

confidence: 99%

“…7 The formation of POAs from transition metal alkoxides (TMAs) involves both polycondensation and coordination polymerization. [1][2][3]8,9 The addition of water to alkoxides leads to the substitution of some alkoxo ligands (OR) by hydroxo (OH) ligands. The latter are the active functions of the condensation reactions shown in Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

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Growth versus Cyclization in the Early Stages of the Polycondensation of Metal Alkoxides

Martin

Sánchez

2005

J. Phys. Chem. B

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The early steps of the polycondensation of transition metal alkoxide have been studied from the chemical and structural points of view. Polyoxoalkoxides are described like macromolecules by the composition of the repeating unit, the degree of polymerization (N), and the radius of gyration (R). The fraction p of binding sites of the coordination sphere of the metal centers occupied by terminal ligands determines N as follows: N proportional, variant pdf (dA-df), where df is the fractal dimension and dA is defined by Np proportional, variant RdA. This approach addresses difficulties raised by both coordinative unsaturation and cyclization in the modelization of the polycondensation of metal alkoxides. The coordinative unsaturation is accounted for by a particularly small value of dA= 1 in the very early steps, while the cyclization frequency is measured by the difference dA-df. This difference is not constant along the polycondensation process, and its dependence on the extent of reaction provides clues for understanding the high apparent kinetics order of gelation often reported in the literature.

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Section: Methodsmentioning

confidence: 99%