This review describes the synthesis and properties of homopolymers and copolymers of monomers containing inorganic–organic hybrid polyhedral oligomeric silsesquioxane (POSS) structures. Monomers, such as styryl-POSS, methacrylate-POSS, norbornyl-POSS, vinyl-POSS, epoxy-POSS, and siloxane-POSS, are included. Both monofunctional and multifunctional monomers are included. Thermoplastic and thermoset systems are considered. Thermal, rheological, and dynamic mechanical properties are described. The synthesis of POSS macromers (monomers) is briefly described. POSS chemicals have been used to prepare nanosized designed novel composites with a variety of potential applications. This review, covering 111 references, is descriptive and not designed to be totally comprehensive. However, the major existing reviews of certain subtopics are noted, allowing the reader to gain a general introduction while providing the information to permit more comprehensive coverage.

Polyhedral Oligomeric Silsesquioxane (POSS) Polymers and Copolymers: A Review

Oligo- and polysiloxanes

Porous polysilsesquioxane gels derived from sol–gel systems based on trifunctional silanes are reviewed. Although it is well known that trifunctional silanes possess inherent difficulties in forming homogeneous gels, increasing attention is being paid on these precursors and resultant porous polysilsesquioxanes because of hydrophobicity, functionality, and versatile mechanical properties. Much effort has been made to overcome the difficulties for homogeneous gelation, and a number of excellent porous materials with various pore properties have been explored. In this critical review, we put special emphasis on the formation of a well-defined macroporous structure by making use of phase separation, which in turn is a serious problem in obtaining homogeneous gels though. Porous polysilsesquioxane monoliths with the hierarchical structure and transparent aerogels with high mechanical durability are particularly highlighted (169 references).

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Controlled pore formation in organotrialkoxysilane-derived hybrids: from aerogels to hierarchically porous monoliths

Viscosity – Molecular Weight Relationships and Unperturbed Dimensions of Linear Chain Molecules

A high-molecular-weight and well-defined ladder polyphenylsilsesquioxane (Ph-LPSQ) was synthesized via a new three-step approach: monomer self-organization in solution, lyophilization, and surface-confined polycondensation. A ladder superstructure, which served as a template to direct the polycondensation, was self-assembled from the 1,3-diphenyl-tetrahydroxy-disiloxane monomer (M) in acetonitrile solution. Following that, it was lyophilized to form a thin layer on the inner surface of a flask. Subsequently, polycondensation of the ordered monomeric thin layer was performed under a triethylamine (TEA) atmosphere. This strategy increased the ladder regularity of the Ph-LPSQ by preventing common complications faced in solution polycondensation of silanol-containing monomers, such as cyclization and gelation side reactions. 29Si NMR analysis showed a very narrow peak (peak width at half-height, w1/2 = 2.5 ppm) at δ = –78.5 (corresponding to a Ph-SiO3/2unit), indicating a high degree of regularity of the poly...

A Well-Defined Ladder Polyphenylsilsesquioxane (Ph-LPSQ) Synthesized via a New Three-Step Approach: Monomer Self-Organization−Lyophilization—Surface-Confined Polycondensation

Kenneth M. Kiser

Papers

Double chain polymers of phenylsilsesquioxane