Tris-cis-tris-trans-dodeca[organo(dimethylorganosiloxy)]cyclododecasiloxanes {RSi(O)[OSiMe2R′]}12. Self-Ordering Features

• Published in: Inorganic chemistry 2011-10, Vol.50 (20), p.10033-10040
• Main Authors: Matukhina, Elena V, Molodtsova, Yulia A, Pozdnyakova, Yulia A, Buzin, Mikhail I, Vasil’ev, Viktor G, Katsoulis, Dimitris E, Shchegolikhina, Olga I
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic2008123

The molecular order and thermotropic transitions of tris-cis-tris-trans-dodeca- [organo(dimethylorganosiloxy)]cyclododecasiloxanes {RSi(O)[OSiMe2R′]}12 (R = Ph, R′ = Me, CH2Cl, Vi; R = Me, Et, Vi, R′ = Me) have been investigated using differential scanning calorimetry, thermogravimetric analysis, and X-ray scattering. The cyclododecasiloxanes with phenyl side groups (R = Ph) can form mesomorphic structures within a very wide temperature range. Compounds with R = Me and Vi are liquids and exhibit microphase separation above their glass transition temperature because of the different nature and structure of the organic R and trimethylsiloxy OSiMe3 side groups. When the side group R = Et, a mesomorphic structure is formed in a substantially more narrow temperature region than that for cycles containing phenyl groups. Thus, the type of side group R in organocyclododecasiloxanes determines their ability for self-ordering into mesomorphic structures and the thermal stability of the mesomorphic state.