cis-Tetra[(organo)(trimethylsiloxy)]cyclotetrasiloxanes: Synthesis and mesomorphic properties
作者:O. I. Shchegolikhina、Yu. A. Pozdnyakova、A. A. Chetverikov、A. S. Peregudov、M. I. Buzin、E. V. Matukhina
DOI:10.1007/s11172-007-0014-3
日期:2007.1
Hydrolytic condensation of organotrialkoxysilanes RSi(OR′)3 (R = Me, Et, Pr, CH=CH2; R′ = OMe, OEt) in the presence of sodium and/or potassium hydroxide gave new alkali organosiloxanolates (M+)4[RSi(O)O−]4}·nL (R = Me, Et, Pr, CH=CH2; M = Na, K; L = R′OH, H2O) in which the main structural fragment is the cyclotetrasiloxanolate fragment cis-[RSi(O)O−]4. Based on these organosiloxanolates, a series of cis-tetra[(organo)(trimethylsiloxy)]cyclotetrasiloxanes was synthesized. For new cyclotetrasiloxanes, the thermotropic transitions and mesomorphic orderings were determined by differential scanning calorimetry, X-ray diffraction analysis, and polarization microscopy. In addition, new mesomorphic compounds were revealed. The character of thermotropic and time evolution of the phase state was found for a mixture of cis-tetra[ethyl(trimethylsiloxy)]-and cis-tetra[phenyl(trimethylsiloxy)]cyclotetrasiloxanes.
有机三烷氧基硅烷 RSi(OR′)3 (R = Me, Et, Pr, CH=CH2; R′ = OMe, OEt) 在氢氧化钠和/或氢氧化钾存在下水解缩合,得到新的碱金属有机硅氧烷醇盐 (M+)4[ RSi(O)O−]4}·nL (R = Me, Et, Pr, CH=CH2; M = Na, K; L = R′OH, H2O) 其中主要结构片段是环四硅氧烷醇片段顺式[RSi(O)O−]4。基于这些有机硅氧烷醇盐,合成了一系列顺式四[(有机)(三甲基硅氧基)]环四硅氧烷。对于新型环四硅氧烷,通过差示扫描量热法、X 射线衍射分析和偏振显微镜测定了热致转变和介晶排序。此外,还发现了新的介晶化合物。发现了顺式四[乙基(三甲基硅氧基)]-和顺式四[苯基(三甲基硅氧基)]环四硅氧烷混合物的热致特性和相态随时间演化的特征。