In comparison to the traditional materials, such as metal, stone, wood, etc, synthetic polymeric materials are playing more and more important roles in social daily life due to its advantages like light-weight, corrosion resistance and easily processed. They are widely used in household appliances, cables, wires, electric devices, transportation, construction materials, etc. However, in air condition most polymeric materials are flammable and easy to burn under a relatively high temperature or in the presence of open fire. In many cases, improving flame retardancy of polymer materials is very important to reduce potential fire risks and life and property loss. Strictly speaking, the objective of flame retarding polymers is to increase the resistance of ignition and to reduce the flame spread with minimal degradation of their properties. Flame retardant materials are extremely important additives in a wide variety of materials and industries, with the increasing world market usage. In the past decade, due to the environment concern caused by the use of halogenated flame retardant, much more attention focused on studying new flame retardants for polymers. Incorporation of additives is the most common way to tune the chemical and physical properties of polymers. In particular, additives that improve the flame retardancy and mechanical properties of polymers without increasing health and environmental risks are in high demand. In recent years, phosphorus-containing molecular flame retardants have gained importance while replacing their halogenated predecessors. Nevertheless, the development of fire-safe polymers by incorporation of FR additives still poses a significant challenge. Firstly, high dosages of the FR additives are often required to achieve the desired fire-safety levels, at which the deterioration of thermal stability and mechanical properties of the corresponding composites are commonly observed. Secondly, the migration of FR molecules onto the polymer surface leads to the release of volatile organic compounds, which is concerned as a serious health-threatening issue.
Metal-Organic Frameworks (MOFs) have been prototyped as polymer additives. The resulting composite materials have been tested in a number of applications exploiting the material porosity, e.g. gas separation, nanofiltration, capture of VOC, and have been shown to exhibit better performance than those of their individual components. It has been also recognized that MOFs themselves exhibit some flame retardant properties as the metal centers within their structure can promote char formation during the combustion of the composite. However, the fire resistant effect of MOFs is limited with respect to molecular FRs which can also offer more fire suppression mechanism by quenching the combustion reactions or forming a non-flammable layer on the burning material. Conveniently, due to their intrinsic porosity, such molecular flame retardants can be incorporated into MOFs as functional guest molecules.
In this project, we aim to develop multifunctional intelligently flame retardant polymeric materials which have significantly impact on new generation polymer-based products in varied application fields. Combing the research background of the researcher, we are developing MOF and its functionalized hybrids as a new generation of polymer composites (figure 1) which have been proved by varies characterizations that this type of additive functions with good efficiency in the improvement of fire retardancy and mechanical properties of polymeric composites. At the same time, the working mechanism of each component are investigated from the perspective of molecular structure.
