Chain mobility in bulky carbosilane modified polymeric siloxane systems

Abstract

C 12 H 22 CdN4O14, triclinic, P¯ (no. 2), a = 7.188(2) Å, b = 8.895(3) Å, c = 9.771(3) Å, α = 63.148(3)°, β = 76.750(3)°, γ = 66.225(3)°, V = 509.2(3) Å 3 , Z = 1, Rgt(F) = 0.0253, wR ref (F 2 ) = 0.0676, T = 296(2) K. CCDC no.: 1484775The crystal structure is shown in the gure. Tables 1 and 2 contain details of the measurement method and a list of the atoms including atomic coordinates and displacement parameters. Source of materialThe title compound was synthesized by a hydrothermal method under autogenous pressure. A mixture of CdCl 2 ·H 2 O

Polymer Chain Relaxation Mechanisms in Siloxane-Carbosilane Systems

“…Very short siloxanes modified at their both ends with bulky (CH 2 ) 2 SiMe 2 Tsi moieties were used as models mimicking the increased steric congestion at siloxane units of linear siloxane co-polymers, side-functionalized with Tsi [5]. The obtained results indicate surprising relaxation trends when the appropriate solutions in CDCl 3 were heated.…”

“…After the modification of terminal siloxane units with carbosilane groups, the cold crystallization of modified hexameric species was totally hindered. Short oligomers with carbosilane moieties, which were intended as models mimicking the increased steric congestion at siloxane units of linear siloxane co-polymers, side-functionalized with Tsi [5], also exhibit glass transitions at relatively high temperatures. However, it is more appropriately attributed to formation of a cooperative configuration of relatively rigid molecules in these systems [16].…”

“…It was previously reported for oligomeric systems modified with Tsi-type groups [5,17,18], that their decomposition under an inert atmosphere involves single stage abstraction of the cabosilane segment. On the other hand highly flexible dimethylsiloxanes typically undergo thermal decomposition by end-biting and chain transfer processes, which can lead to a complete depolymerization with the formation of cyclic siloxanes [19].…”

“…Carbosilane derivatives of the tris(trimethylsilyl)methyl (Tsi) moiety, due to their exceptional steric hindrance, have been extensively used both in organometallic [1,2] and polymer chemistry [3][4][5][6][7][8][9][10][11][12]. Tsi-modified polymeric materials exhibit quite unique properties.…”

“…Bringing sterically demanding Tsi moieties into polysiloxane materials should be of great importance for their properties. The relationship between the mobility of a polymer chain and the type of Tsi carbosilane moiety, and its distribution along the main backbone, was recently studied for an homologous series of poly(dimethyl-methyl)siloxanes [5]. It was found that Tsitype side groups can restrict the movement of polymer segments and in consequence lead to a tremendous increase of the glass transition temperature and thermal stability of all the studied siloxane materials.…”