Abstract
Five low-dispersity star-shaped polydimethylsiloxanes were synthesized. The macromolecules of the polymers contain the same branching-out center, a cis-tetraphenylcyclotetrasilsesquioxane moiety, and the same number of arms, but with different lengths (n = 15, 21, 48, 75, and 123 Si(Me)2O units). Their properties were studied by a set of physicochemical analytical methods. Viscometric studies showed that the macromolecules of the Ph4-15, Ph4-21, Ph4-48, and Ph4-75 polymers are small-sized dense balls both in solution and in melt. DSC studies identified an unusual effect of the cyclic core on the thermal behavior of the Ph4-15, Ph4-21, and Ph4-48 polymers. Its incorporation suppresses the crystallization of PDMS-arms (up to n = 48 Si(Me)2O units) at concentrations four times lower than those of known modifiers and does not affect the glass transition temperature (ca. -124 °С).
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