The incorporation of inorganic filler particles is an effective approach to enhance the mechanical properties of polymer composites. The physical characteristics are influenced by the interaction between the filler and the polymer. Therefore, factors such as the surface-to-volume ratio and surface modification play a crucial role. In addition to strategies aimed at modifying the filler beforehand to influence these physical properties, our approach involves a post-treatment of the composite. This study focuses on introducing stimuli-responsive properties into a composite material by altering the chemical composition and structure of the filler particles. Instead of creating a responsive polymer, we utilize photo-degradable organosilica nanoparticles that can modify the mechanical properties of a polymer/filler composite after it has been formed.

In our work we adapted [1] and improved light-degradable organosilica for our purposes. We showed that light-triggered degradation takes place. In consonance with literature we showed that a functionalization improved the homogeneity of the composites. In UV experiments we proved that the chemical change of the filler particles occurs as well. Further, we have been able to measured a light-triggered stiffening effect and therefore proved that organosilica nanoparticles can be for mechanical adaptive composites.

First, synthesis of the nitro-benzylether ether containing bissilane had to be adapted. For the composite materials, we then synthezised and characterized the light-degradable organosilica nanoparticles. Via electron microscopy and UV-vis, the degradation of the particles was tracked. To improve incorporation of the particles into the silicone we functionalized the surfaces with a vinyl group. Finally, we exposed the composites with UV-light and measured the mechanical properties before and after irradiation. In dynamic mechanical analysis (DMA) and tensile test measurements we found that the composites showed enhanced storage modulus and E-modulus after UV-treatment.

References

[1] De Cola et al., Chem. Mater., 2020, 32, 392–399.

[2] F. Klodwig et al., Adv Mater Interfaces, 2024, 2400574.