Highly Thermally Stable, Reversible, and Flexible Main Chain Type Benzoxazine Hybrid Incorporating Both Polydimethylsiloxane and Double-Decker Shaped Polyhedral Silsesquioxane Units through Diels-Alder Reaction.

This work synthesizes a new bifunctional furan derivative (PDMS-FBZ) through a sequence of hydrosilylation of nadic anhydride (ND) with polydimethylsiloxane (PDMS), reaction of the product with p-aminophenol to form PDMS-ND-OH, and its subsequent Mannich reaction with furfurylamine and CH2 O. Then, the main chain-type copolymer PDMS-DABZ-DDSQ is prepared through a Diels-Alder (DA) cycloaddition of PDMS-FBZ with the bismaleimide-functionalized double-decker silsesquioxane derivative DDSQ-BMI. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy confirm the structure of this PDMS-DABZ-DDSQ copolymer; differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) reveal it to have high flexibility and high thermal stability (Tg = 177 °C; Td10 = 441 °C; char yield = 60.1 wt%); contact angle measurements reveal a low surface free energy (18.18 mJ m-2 ) after thermal ring-opening polymerization, because the inorganic PDMS and DDSQ units are dispersed well, as revealed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This PDMS-DABZ-DDSQ copolymer possesses reversible properties arising from the DA and retro-DA reactions, suggesting its possible application as a functional high-performance material.

Preparation of T8 and double-decker silsesquioxane-based Janus-type molecules: molecular modeling and DFT insights.

We present a methodology for the synthesis of inorganic-organic Janus-type molecules based on mono-T8 and difunctionalized double-decker silsesquioxanes (DDSQs) via hydrosilylation reactions, achieving exceptionally high yields and selectivities. The synthesized compounds were extensively characterized using various spectroscopic techniques, and their sizes and spatial arrangements were predicted through molecular modelling and density functional theory (DFT) calculations. Quantum chemical calculations were employed to examine the interactions among four molecules of the synthesized compounds. These computational results allowed us to determine the propensity for molecular aggregation, identify the functional groups involved in these interactions, and understand the changes in interatomic distances during aggregation. Understanding the aggregation behaviour of silsesquioxane molecules is crucial for tailoring their properties for specific applications, such as nanocomposites, surface coatings, drug delivery systems, and catalysts. Through a combination of experimental and computational approaches, this study provides valuable insights into the design and optimization of silsesquioxane-based Janus-type molecules for enhanced performance across various fields.

High-Thermal Stable Epoxy Resin through Blending Nanoarchitectonics with Double-Decker-Shaped Polyhedral Silsesquioxane-Functionalized Benzoxazine Derivatives.

A series of di-functional benzoxazine (BZ) monomers was synthesized, specifically the double-decker silsesquioxane (DDSQ) cage structure (DDSQ-BZ). Comparative analyses were conducted between DDSQ-BZ monomers and the most commonly utilized bisphenol A-functionalized bifunctional benzoxazine (BPA-BZ) monomer. DDSQ-BZ compounds possess better thermal properties such as high char yield and high thermal decomposition temperature (Td10) after thermal ring-opening polymerization (ROP) because the inorganic DDSQ cage nanostructure features a nano-reinforcement effect. In addition, blending inorganic DDSQ-BZ compounds with epoxy resin was explored to form organic/inorganic hybrids with enhanced thermal and mechanical properties following thermal ROP. The improvement in mechanical properties is primarily attributed to the network structure formed by the cross-linking between DDSQ-BZ and the epoxy resin during thermal ROP, as well as hydrogen bonding interactions formed between the hydroxyl groups generated during thermal ROP and the Si-O-Si bonds in the DDSQ structure.

Novel hybrid composites based on double-decker silsesquioxanes functionalized by methacrylate derivatives and polyvinyl alcohol as potential materials utilized in biomedical applications.

The use of diverse biomaterials for regenerative medicine is constantly evolving. Therefore, looking for easy-to-scale-up materials in terms of preparation, less complex composition, and featuring structural and chemical stability seems justified. In this work, we report the preparation of double-decker silsesquioxane-based (DDSQ-based) composites, which, according to our best knowledge, have never been used as biomaterials. A family of methacrylate-substituted DDSQs was obtained starting from the previously reported hydroxyalkyl double-decker silsesquioxanes. In the resulting hybrids, methacrylate groups are attached to each other's lateral silicon atoms of DDSQ in trans positions, providing an excellent geometry for forming thin layers. In contrast to pure organic methacrylates, the covalent bonding of methacrylate derivatives to inorganic silsesquioxane core improves mechanics, cell adhesion, and migration properties. Furthermore, to increase the hydrophilicity of the resulting DDSQ-based hybrids, polyvinyl alcohol (PVA) was added. The entire system forms an easy-to-obtain two-component (DDSQ-PVA) composite, which was subjected without any upgrading additives to biological tests later in the research. The resulting biomaterials fulfill the requirements for potential medical applications. Human fibroblasts growing on prepared hybrid composites are characterized by proper spindle-shaped morphology, proliferation, and activation status similar to control conditions (cells cultured on PVA), as well as increased adhesion and migration abilities. The obtained results suggest that the prepared biomaterials may be used in regenerative medicine in the future.

A Brief Review on Selected Applications of Hybrid Materials Based on Functionalized Cage-like Silsesquioxanes.

Rapid developments in materials engineering are accompanied by the equally rapid development of new technologies, which are now increasingly used in various branches of our life. The current research trend concerns the development of methods for obtaining new materials engineering systems and searching for relationships between the structure and physicochemical properties. A recent increase in the demand for well-defined and thermally stable systems has highlighted the importance of polyhedral oligomeric silsesquioxane (POSS) and double-decker silsesquioxane (DDSQ) architectures. This short review focuses on these two groups of silsesquioxane-based materials and their selected applications. This fascinating field of hybrid species has attracted considerable attention due to their daily applications with unique capabilities and their great potential, among others, in biomaterials as components of hydrogel networks, components in biofabrication techniques, and promising building blocks of DDSQ-based biohybrids. Moreover, they constitute attractive systems applied in materials engineering, including flame retardant nanocomposites and components of the heterogeneous Ziegler-Natta-type catalytic system.

Double-Decker-Shaped Polyhedral Silsesquioxanes Reinforced Epoxy/Bismaleimide Hybrids Featuring High Thermal Stability.

In this study, we synthesized bismaleimide into a functionalized double-decker silsesquioxane (DDSQ) cage. This was achieved by hydrosilylation of DDSQ with nadic anhydride (ND), reacting it with excess p-phenylenediamine to obtain DDSQ-ND-NH2, and treating with maleic anhydride (MA), which finally created a DDSQ-BMI cage structure. We observed that the thermal decomposition temperature (Td) and char yield were both increased upon increasing the thermal polymerization temperature, and that these two values were both significantly higher than pure BMI without the DDSQ cage structure since the inorganic DDSQ nanoparticle could strongly enhance the thermal stability based on the nano-reinforcement effect. Based on FTIR, TGA, and DMA analyses, it was found that blending epoxy resin with the DDSQ-BMI cage to form epoxy/DDSQ-BMI hybrids could also enhance the thermal and mechanical properties of epoxy resin due to the organic/inorganic network formation created by the ring-opening polymerization of the epoxy group and the addition polymerization of the BMI group due to the combination of the inorganic DDSQ cage structure and hydrogen bonding effect. The epoxy/DDSQ-BMI = 1/1 hybrid system displayed high Tg value (188 °C), Td value (397 °C), and char yield (40.4 wt%), which was much higher than that of the typical DGEBA type epoxy resin with various organic curing agents.

Slick Synthetic Approach to Various Fluoroalkyl Silsesquioxanes-Assessment of their Dielectric Properties.

We present a smart and efficient methodology for the synthesis of a variety of fluorinated silsesquioxanes (SQs) with diverse Si-O-Si core architecture. The protocol is based on an easy-to-handle and selective hydrosilylation reaction. An investigation on the placement of the reactive Si-HC=CH2 vs. Si-H in the silsesquioxane, as well as silane vs. olefin structure, respectively, on the progress and selectivity of the hydrosilylation process, was studied. Two alternative synthetic pathways for obtaining a variety of fluorine-functionalized silsesquioxanes were developed. As a result, a series of mono- and octa- T8 SQs, tri- 'open-cage' T7 SQs, in addition to di- and tetrafunctionalized double-decker silsesquioxane (DDSQ) derivatives, were obtained selectively with high yields. All products were characterized by spectroscopic (NMR, FTIR) techniques. Selected samples were subjected to the measurements revealing their dielectric permittivity in a wide range of temperatures (from -100 °C to 100 °C) and electric field frequencies (100-106 Hz).

Functional Polyimide/Polyhedral Oligomeric Silsesquioxane Nanocomposites.

The preparation of hybrid nanocomposite materials derived from polyhedral oligomeric silsesquioxane (POSS) nanoparticles and polyimide (PI) has recently attracted much attention from both academia and industry, because such materials can display low water absorption, high thermal stability, good mechanical characteristics, low dielectric constant, flame retardance, chemical resistance, thermo-redox stability, surface hydrophobicity, and excellent electrical properties. Herein, we discussed the various methods that have been used to insert POSS nanoparticles into PI matrices, through covalent chemical bonding and physical blending, as well as the influence of the POSS units on the physical properties of the PIs.