Open-cage silsesquioxane necklace polymers having closed-cage silsesquioxane pendants

Abstract

A novel POSS monomer design has been proposed; a closed-cage POSS was tethered to an open-cage POSS, and the remaining two functional groups were employed for polymerization. The thermal and optical properties of the obtained main-chain type POSS polymers can be widely tuned by the substituents at the corners of the POSSs.

Polymers and cyclic compounds based on a side‐opening type cage silsesquioxane

“…It is probable that the SO‐POSS has much higher flexibility than the close‐cage silsesquioxanes, resulting in the relatively low T g values of the obtained polymers. This accords with the result in the case of a corner‐opening type POSS, in which the melting point is much lower than that of the corresponding closed‐type POSS analogue …”

“…The chemical structures of Polymers 6 – 8 were determined by NMR spectroscopy, and their molecular weights were estimated by SEC with polystyrene standards. It was reported that the molecular weights of main chain type POSS polymers are underestimated by SEC 11a. This is probably because of the spherical molecular structures of POSSs.…”

“…Increasing attention has been given to main‐chain type POSS polymers for creation of POSS‐based materials instead of conventional POSS‐assisted materials, in which POSS is utilized for enhancement of materials properties of organic polymers. The major challenge for producing POSS monomers lies in precisely introducing two reactive sites into POSS backbone because each corner of POSS has the same reactivity.…”

“…The polyimides10a, c and polysiloxanes10b are thermally stable and optically transparent, and the polyazomethine10d can be used for fabrication of a bilayer device using a same solvent due to the spontaneous insolubilization on a substrate. In addition, we recently reported open‐cage silsesquioxane necklace polymers having closed‐cage silsesquioxane11a or triphenylsilane pendants,11b in which one of the three silanol groups of an open‐cage silsesquioxane is capped, and the remaining two silanol groups are employed for the polymerization [Chart (c)].…”

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

“…However, they offer interesting synthetic possibilities due to the opportunity to introduce more than one functional group within the silsesquioxanes core bearing at the same time also inert ones. As a result, the perspectives for the further development of this group of compounds are vast, from nanostructured coating films [13], silica-grafted catalysts [21,22], tripodal ligands for transition metals [23], novel cage host molecules [24], aggregates in cosmetics and food manufacturing [25,26], or dentistry [27,28] to polymers modifiers as cross-linking agents [29][30][31][32][33][34]. Multi-functional SQs may additionally offer the possibility to obtain three-dimensional (3D) copolymeric networks, leading to substantial improvement in their physicochemical properties, i.e., increased thermal and oxidation resistance, mechanical properties, e.g., hardness, as well as the reduction of flammability, heat evolution, viscosity during processing, etc.…”