POSS (polyhedral oligomerie silsesquioxane) is called polyhedral oligomeric silsesquioxane. Its structure is abbreviated as (RSiO1.5)n, and its structure is mainly cage-like, incomplete cage-like, trapezoidal, and irregular. It is the only molecular-level nano-hybrid material at present. Among them, the most researched and applied POSS molecules are those with cage structure, shown in Figure 1. Reactive or non-reactive organic functional groups can be connected to the Si atoms at the apex angle of the POSS cage structure to achieve the purpose of reactive compatibility with the polymer matrix or molecular-level dispersion, thereby greatly improving the performance of the nanocomposites. POSS modified organic and inorganic nanohybrid materials have become one of the focuses this year.
Figure 1. Structure of POSS.
POSS nanohybrid materials have excellent performance. The introduction of POSS can not only improve the thermal stability of the materials, but also improve the surface hardness and mechanical strength of the materials, enhance the flame retardancy of the materials, and reduce the dielectric constant of the polymers. POSS itself is tasteless and non-toxic, and has good biocompatibility. With the further maturity of the synthesis method of POSS nanohybrid materials and the further acceleration of commercialization, it has great application potential in the fields of optics, medicine and biology.
- Luminescent material: POSS nanohybrid materials made by combining luminescent groups with POSS can significantly improve the light color and photoelectrical properties of luminescent materials, and have a high application prospect in the field of luminescent materials. And the modified POSS nanohybrid materials can obviously improve the analysis accuracy of optical instruments and provide greater convenience for scientific research work due to its good transparency. Therefore, it is widely used in optical instruments.
- Mesoporous material: The porous voids between the silsesquioxane cubes can be used to prepare low-cost porous materials, effectively overcoming the shortcomings of conventional preparation methods for preparing micropores or mesoporous materials with high specific surface area, which have a long preparation period and poor performance.
- Liquid crystal material: The highly symmetric structure of POSS offers the possibility of preparing liquid crystal materials or star dendrimers. The unique multi-arm structure and reactive group provide a good platform for the design and synthesis of liquid crystal material compounds.
- Flame retardant material: Polyhedral oligomeric silsesquioxane hybrid polymer is a star-shaped polyhalogen-free flame retardant polymer, which is a development direction of high flame retardant materials. Because POSS has a high melting point and low volatility, its Si-O-Si inorganic core can impart excellent flame retardancy to polymer materials, and is considered to be an environmentally friendly additive that can greatly reduce the emission of harmful substances. Experiments show that the introduction of POSS greatly improves the flame retardant properties of polymer materials.
- Catalyst carrier: Different organic functional groups, combined with the pore structure of POSS-like molecular sieve, have a wide range of applications in catalysis and gas adsorption.
- Biomedical material: POSS frameworks with specific hydrocarbon functional groups show strong affinity for liver cells, which makes it possible for POSS to be used as a drug release material. POSS nanohybrid materials are also used for a new type of dental binder. This binder yields a high-strength resin that penetrates into the surface of the eroded tooth, enhancing the bonding force between the repair material and the tooth.
- Hui Zhou,a Qun Yea and Jianwei Xu. Polyhedral oligomeric silsesquioxane-based hybrid materials and their applications. Mater. Chem. Front., 2017, 1, 212-230.
- Kai Xiang, Yanmin Li, Caihong Xu and Shuhong Li. POSS-based organic–inorganic hybrid nanomaterials: aggregation-enhanced emission, and highly sensitive and selective detection of nitroaromatic explosives in aqueous media. J. Mater. Chem. C, 2016, 4, 5578-5583.
- M. Jesus Fern´andez, M. Synthesis, characterization and properties of telechelic hybrid biodegradable polymers containing polyhedral oligomeric silsesquioxane (POSS). RSC Adv., 2014, 4, 21435–21449.