Tripodal polyhedral oligomeric silsesquioxanes as a novel class of three-dimensional emulsifiers

Abstract

Tripodal amphiphilic molecules toward organic-inorganic hybrid emulsions were successfully synthesized based on incompletely condensed polyhedral oligomeric silsesquioxanes (POSSs). The three silanol groups provide an excellent scaffold for the construction of three-dimensional amphiphilic molecules, thus well-defined tripodal amphiphilic POSS derivatives were readily synthesized. Thermal analyses revealed that an incompletely condensed POSS exhibited lower crystallinity without loss of thermal stability in comparison with a completely condensed POSS, whereas readily forms aggregates because of its high crystallinity. The newly synthesized tripodal amphiphilic POSSs possessed good solubility in water and effectively stabilized oil-in-water emulsions, while a conventional mono-substituted amphiphilic POSS did not work as an emulsifier because of its lack of water solubility. The prepared organic-inorganic hybrid emulsions were stable against coalescence, and no demulsification occurred over 1 month.

Highly Efficient Route for the Synthesis of a Novel Generation of Tetraorganofunctional Double‐decker Type of Silsesquioxanes

“…At the same time, chemists are looking for synthetic routes exploiting among others hydrosilylation reaction to obtain novel, functionalized Si-based reagents with a specific structure such as silsesquioxanes. [17][18][19][20][21][22][23][24][25][26][27] While hydrosilylation of olefins with silanes has been widely studied, [3,28] the reports on T 8 silsesquioxanes are limited [5,6,[29][30][31][32][33][34] and for double-decker systems of both closed (D 2 T 8 [4,19,25,[35][36][37] ) and opened (M 4 T 8 [38][39][40][41][42][43] ) structure even more scant. [5] Cage-like derivatives have driven much attention due to specific physicochemical properties (governed by the nature of their silicate rigid core and by the number and type of functional groups attached to it) affecting directions of their broad applications from material chemistry to medicine.…”

“…[12,15,16] Taking research in the field of macromolecular DDSQ-based frameworks of hybrid nature into account, difunctionalized doubledecker silsesquioxanes are of greatest interest due to the possibility of their incorporation into the main chain of the polymer. [17][18][19][20][21][22][23][24][25][26][27] While hydrosilylation of olefins with silanes has been widely studied, [3,28] the reports on T 8 silsesquioxanes are limited [5,6,[29][30][31][32][33][34] and for double-decker systems of both closed (D 2 T 8 [4,19,25,[35][36][37] ) and opened (M 4 T 8 [38][39][40][41][42][43] ) structure even more scant. Miyashita and co-workers were the first to apply hydrosilylation as a method to modify tetrahydrosubstituted DDSQ (DDSQ-4OSiH) compound with N-vinylcarbazole performed in the presence of Karstedt's catalyst.…”

Fabrication of composite films with poly(methyl methacrylate) and incompletely condensed cage‐silsesquioxane fillers

“…For example, dumbbell- 21,22 and star-shaped 23,24 POSS oligomers (dimer and nonamer, respectively) produce optically transparent amorphous films, whereas monomeric POSS compounds form turbid aggregates. 27 Notably, melting point of IC-POSS is remarkably lowered from CC-POSS, while there is no significant difference in thermal stability. 27,28 An emulsifier based on IC-POSS stabilizes the emulsions, but that of CC-POSS analogue did not work.…”

“…It has been found that collapse of the symmetry of POSSs is an effective technique for suppression of the crystallinity. 27,28 An emulsifier based on IC-POSS stabilizes the emulsions, but that of CC-POSS analogue did not work. Recently, we have found that incompletely-condensed POSSs [IC-POSSs, Chart 1(b)], which are traditionally employed as precursors for monofunctionalized completely condensed POSSs [CC-POSSs, Chart 1(a)], 25,26 possess excellent dispersibility due to the lowsymmetrical and flexible open-cage structure.…”

Preparation of Tri(alkenyl)functional Open-Cage Silsesquioxanes as Specific Polymer Modifiers

“…On the other hand, open-cage silsesquioxanes, i.e., not-completely condensed systems have recently attracted much attention. The silsesquioxane trisilanol precursors enable the introduction of three reactive substituents to the Si-O-Si core by means of stoichiometric (hydrolytic condensation), but also catalytic (e.g., hydrosilylation, arylation, O-silylation), processes using functional groups that are already attached to the SQ core [8][9][10][11][12][13][14][15][16]. The symmetry of their trifunctional T 7 open-cage derivatives is changed due to the lack of one vertex in the structure, which affects their physical properties (i.e., changes in molecular packing, melting points) [9,[17][18][19][20].…”