Synthesis and Thermal Properties of Fully Aromatic Polysilarylenesiloxanes

Abstract

A new type of fully aromatic polysilarylenesiloxanes showing high T g was synthesized via the solution polymerization from the bis(diphenylhydroxysilyl)arylene monomers. And the thermal properties of these monomers and polymers were investigated by using differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The monomers containing the diphenylsilanol group showed higher melting temperatures and thermal degradation temperatures than those of the monomers containing the dimethylsilanol group. The obtained fully aromatic polysilarylenesiloxanes were insoluble powders, and showed no weight loss in air below 500 C. No glass transition was detected according to the DSC measurements, whereas 3a and 3b showed melting points at 323 and 391 C, respectively. However, 3b held solid-state at melting point. It would be caused by a cross-linking reaction occurring with melting simultaneously. It was found that these were the thermally stable polymer-solids consisted of the organosiloxane polymers.

Syntheses and Properties of Silicon-containing, Soluble and Fully Aromatic Polymers

“…DSC curves of , and  were drawn in Fig.5.  was a crystalline polymer, showing 334ºC of  m , similar to the fully aromatic polysil arylenesiloxanes in our previous paper [6], but the crystallinity of  would be lower than that of them because  g of  was clearly observed at 116ºC. On the contrary,  was an amorphous polymer, showing 93ºC of  g although the  g was quite different from temperature and time of meltpolycondensation, as mentioned above (See Table I).…”

“… and showed 529ºC and 523ºC of  d5 , respectively, and did excellent thermal stability similar to the fully aromatic polysilarylenesiloxanes in our previous [6,7]. Although  had experienced unexpected large weight loss during the meltpolycondensation, the TG curve of obtained  almost coincided with that of .…”

“…For example, poly (tetramethyl silphenylenesiloxane), PTMPS, of a typical poly silarylenesiloxane showed melting temperature,  m , of 135ºC, glass transition temperature,  g , of 20ºC and thermal degradation temperature,  d , of 411ºC [2][3][4][5][6]. If a new type of polysilarylenesil oxane showing a higher  g or  m than PTMPS is obtained, it is possible that the polysilarylenesil oxane is applied to such heatresistant materials.…”

“…If a new type of polysilarylenesil oxane showing a higher  g or  m than PTMPS is obtained, it is possible that the polysilarylenesil oxane is applied to such heatresistant materials. In previous studies, we had reported fully aromatic polysilarylenesiloxane having tetra phenyldisiloxane units instead of tetramethyl disiloxane units, which showed high  m over 300ºC and no solubility in common solvents [6]. On the other hand, because of insoluble fully aromatic polysilarylenesiloxanes, meltpoly condensation of the corresponding disilanol monomers had be conducted to successfully prepare insoluble and amorphous films [7].…”

Synthesis of Polysilsesquioxanes with Double-Decker Silsesquioxane Repeating Units

“…Introduction of bulky and rigid moieties like phenylene, naphthylene, anthrylene, phenanthrylene and adamantyl moieties in main chain exhibits high T g and good thermal stabilities of the polysiloxanes [7][8][9][10][11]. However, this introduction of organic moieties breaks the continuity of Si-O-Si backbone in the chemical structure of the formed polymer.…”