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Flame retardant Nanocontainers

Periodic Reporting for period 1 - NOFLAME (Flame retardant Nanocontainers)

Reporting period: 2016-03-01 to 2018-02-28

NOFLAME has proposed a unique and competitive program for the development of polymeric flame retardant nanocontainers. The nanocontainers have been synthesized in our laboratory during this fellowship with the goal to open an alternative to help solve the problems of poor dispersion and low interfacial adhesion of the inorganic and hybrid nanomaterials applied for flame retardant applications so far. Furthermore, the ability to encapsulate a wide range of substances makes the nanocontainers highly attractive to develop multifunctional nanomaterials in future applications.

Since we live in the polymer age, and polymers are highly flammable, flame retardants have become a key component in the industry to reduce the impact of fires. Flame retardants save people's lives, their property and in some cases even the environment. However, traditional flame retardants like halogenated compounds present some serious disadvantages, like environmental persistence and toxicity, and their use is currently limited by REACH (EC 1907/2006). Halogen-free flame retardants like organophosphorus compounds or metal hydroxides, on the other hand, deteriorate the mechanical properties and have poor effectiveness. Thus, over the last years, the development of fire-resistant nanomaterials encloses one of the most promising challenges in the area of flame retardancy, considering that they can simultaneously enhance mechanical and thermal properties.

From a scientific perspective, the main activities within NOFLAME were: 1) the synthesis of nanocontainers and the encapsulation of organic and inorganic flame retardant compounds, 2) the introduction of the nanocontainers in a polymer matrix and 3) the evaluation of their influence on the mechanical and flame retardant properties of the final material. This project was only possible combining the expertise of the host MPIP Institute (Max Planck Institute for Polymer Research) and the partner BAM Institute (Bundesanstalt für Materialforschung und –prüfung).
Several mostly inorganic nanomaterials have been reported as flame retardants. Nevertheless, they also show considerable damage in the mechanical properties of the polymer matrices, as a result of their poor dispersion and poor interfacial adhesion due to their inorganic nature. To overcome these disadvantages, the NOFLAME project proposed a new approach based on the development of polymeric flame retardant nanocontainers with high thermal stability, low flammability and good compatibility with polymeric matrices. This approach proposes a novel organophosphorus monomer with high thermal stability as a chemical building block for the generation of nanocontainers in miniemulsion (Figure NOFLAME TOC). The average particle size and particle size distribution of the nanocontainers were determined by dynamic light scattering (DLS). Morphological studies were performed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Furthermore, the stabilization and dispersion of the nanocontainers in different matrices was studied. The obtained results by thermogravimetric analysis (TGA) and microscale combustion calorimetry (MCC) have proved an improvement of the flame retardant properties in the final material due to the activity of nanocontainers as flame retardants.

In the course of that action, I have supervised 1 Bachelor student and 1 Master student. The NOFLAME project information has been disseminated in 2 talks and 1 invited talk at international conferences, as well as 12 presentations in indoor seminars and workshops at the MPIP Institute and BAM Institute. The investigation has produced important results drafted on 2 manuscripts for high impact peer-reviewed journals. I also developed my analytical and comprehending skills by writing 2 high impact review publications in which I spread my acquired knowledge during the NOFLAME project about flame retardants, nanomaterials and organic synthesis. I also took part in several vulgarization events such as Lab tours and demonstrations for kids, college students and the general public.
The knowledge acquired in this research project will directly result in an improved understanding of flame retardant mechanisms and dispersion of polymeric structures by other researchers in the field of flame retardant nanomaterials, as well as in the field of colloid science. Furthermore, the impact of this research will not only be in the academic area but also will have an important impact in the polymer industry sector, due to the high interest of the companies to change their common flame retardants for others less toxic according to REACH (EC 1907/2006).

On the other hand, the investigations included in the NOFLAME project also have contributed to the knowledge of the scale-up of polymeric miniemulsion by microfluidizer. Currently, scaling studies of new materials for bio-applications are being carried out by the group.

Finally, this project has initiated a new approach that not only meets the challenges of the dispersion of nanomaterials in an organic matrix and the enhancement of its flame retardant properties, but also provides us the possibility of the encapsulation of additional features. It opens up the door for new applications, where the application of organic shells is limited by their low thermal stability and high flammability. The encapsulation of paraffin waxes, a thermal energy storage material for buildings, is such an example.
TOC Figure of NOFLAME process