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A series of carbosilane dendritic macromolecules grown from four directions of a tetrahedral central core has been synthesized and characterized. In the synthesis tetravinylsilane is used as the central core molecule and dichloromethylsilane as the propagation unit. Two reactions are involved in the synthesis of each generation: hydrosilylation of vinylsilane with dichloromethylsilane and nucleophilic replacement of silicon chloride by vinylmagnesium bromide. The reaction conditions for hydrosilylation must be well controlled. After purification by chromatography on silica gel pure products for each generation are obtained. The and 13C NMR spectra are consistent with the proposed structures. The molecular weights of the resulting carbosilane dendrimers have been determined by vapor pressure osmometry or light scattering. Their experimental values are in very good agreement with the theoretical values. The dilute solution properties of these dendrimers are different from linear polymers.

A dendrimer carbosilane containing 32 Si—Cl bonds in the perimeter has been prepared and has been used as a coupling agent to prepare 32-arm star polybutadienes. The dilute-solution properties 〈RG2〉, A2, [η], and D0 have been measured in one good solvent and in one ¸ -solvent. The dimensions of the 32-arm star polymers are compared with those of linear polymers at constant molecular weight. It is shown that the 32-arm star polybutadiene has the characteristic properties of a hard-sphere molecule in dilute solution. The equivalent hard-sphere radii calculated from A2, D0 and [η] are identical and 1.29 times larger than the root mean-square radius of gyration. The Daoud—Cotton scaling model for stars is also tested.

Graphite carbon nitride (g-C3N4), as one of the green and efficient heterogeneous photocatalysts, is applied for photo atom transfer radical polymerization (photo-ATRP) without any additives. The polymerization was instantly switched...