Tris-cis-tris-trans-dodeca[organo(dimethylorganosiloxy)]cyclododecasiloxanes {RSi(O)[OSiMe2R']}12. Self-ordering features |
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Authors: | Matukhina Elena V Molodtsova Yulia A Pozdnyakova Yulia A Buzin Mikhail I Vasil'ev Viktor G Katsoulis Dimitris E Shchegolikhina Olga I |
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Institution: | Department of Physics, Moscow State Pedagogical University, Malaya Pirogovskaya St. 1, Moscow 119882, Russia. |
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Abstract: | The molecular order and thermotropic transitions of tris-cis-tris-trans-dodeca- organo(dimethylorganosiloxy)]cyclododecasiloxanes {RSi(O)OSiMe(2)R']}(12) (R = Ph, R' = Me, CH(2)Cl, 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 OSiMe(3) 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. |
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