Synthesis of a Novel Bifunctional Epoxy Double-Decker Silsesquioxane: Improvement of the Thermal Stability and Dielectric Properties of Polybenzoxazine

In this study a new type of bifunctional epoxy compound (DDSQ-EP) based on double-decker silsesquioxane (DDSQ) was synthesized by process of alkaline hydrolysis condensation of phenyltrimethoxysilane and corner capping reaction with dichloromethylvinylsilane, followed by epoxidation reaction of vinyl groups. The resultant structures were confirmed using Fourier transform infrared spectrometry, nuclear magnetic resonance spectrometry and time-of-flight mass spectrometry, respectively. The DDSQ-EP was incorporated into polybenzoxazine to obtain the PBZ/DDSQ-EP nanocomposites. The uniform dispersion of DDSQ-EP in the nanocomposites was verified by X-ray diffraction and scanning electron microscope. The reactions occurred during the curing of the composites and were investigated using infrared spectroscopy of segmented cures. Dynamic mechanical analysis and thermal gravimetric analysis indicated that the storage modulus, glass transition temperature and thermal stability of PBZ/DDSQ-EP were increased in comparison with pure benzoxazine resins. Assessment of dielectric properties demonstrated that the dielectric permittivity and dielectric loss of polybenzoxazine decreased slightly because of the addition of DDSQ-EP.

Polyphenylsilsesquioxanes. New structures-new properties

The review describes the synthesis and properties of various forms of polyphenylsilsesquioxane (PPSQ). Among the forms described, we present the well-known ladder (l-PPSQ) and polyhedral (p-PPSQ) forms, from the first studies to the latest achievements. The practical prospects of these compounds and the possibility of their modification are estimated. These PPSQ have a regular polycyclic structure, which allowed us to compare them with random polycyclic analogs (r-PPSQ). The last part of the review describes the acyclic PPSQ (a-PPSQ) obtained recently. The methods for their synthesis and modification are presented. Modification of (a-PPSQ) allows two new forms of PPSQ to be obtained. The first one is a hyperbranched PPSQ. The second one is a globular PPSQ or a nanogel as it is called by the authors. Both forms are of great interest because their physicochemical properties differ greatly from the known ones (l-PPSQ, p-PPSQ, r-PPSQ). The areas of practical application of the new PPSQ forms are predicted.

The review describes the synthesis and properties of various forms of polyphenylsilsesquioxane (PPSQ).

Synthesis, self-assembly and self-healing properties of organic–inorganic ABA triblock copolymers with poly(POSS acrylate) endblocks

A novel organic–inorganic ABA triblock copolymer with a poly(acrylate amide) (PAA) midblock and poly(POSS acrylate) [P(POSS)] endblocks was synthesized via sequential reversible addition–fragmentation chain transfer (RAFT) polymerization.

Synthesis of diblock copolymers consisting of POSS-containing random methacrylate copolymers and polystyrene and their cross-linked microphase-separated structure via fluoride ion-mediated cage scrambling

POSS-containing diblock copolymers were synthesized for the formation of cross-linked microphase-separated structure.

Organic-Inorganic Nanocomposites via Self-Assembly of an Amphiphilic Triblock Copolymer Bearing a Poly(butadiene-g-POSS) Subchain in Epoxy Thermosets: Morphologies, Surface Hydrophobicity, and Dielectric Properties

Organic-inorganic nanocomposites composed of polyhedral oligomeric silsesquioxane (POSS) and epoxy resin were prepared via self-assembly of an amphiphilic triblock copolymer bearing a poly(POSS) midblock in epoxy thermosets. First, this organic-inorganic amphiphilic triblock copolymer was synthesized via hydrosilylation of heptaphenylhydro POSS with an existing triblock copolymer containing a short polybutadiene midblock. It was found that this novel amphiphilic block copolymer can self-assemble into nanophases in epoxy thermosets. In the presence of preformed nanophases, the curing reaction was performed, and the organic-inorganic nanocomposites containing poly(POSS) microdomains were thus obtained. Compared with plain epoxy, the as-obtained thermosets exhibited enhanced surface hydrophobicity; the enhanced surface hydrophobicity is attributed to enrichment of the POSS component at the surface of the materials. Owing to the formation of poly(POSS) microdomains, the dielectric constants of the materials significantly reduced, whereas the dielectric loss remained almost unchanged.