Ultraviolet (UV) degradation is one of the most important challenges of waterborne coatings in exterior applications. One of the ways to address this issue is addition of radical scavenging species within the polymer matrix. Herein, hybrids of graphene (G) and multiwall carbon nanotubes (CNTs) in different ratios are used as radical scavenging species. Evaluated by electron paramagnetic resonance spectroscopy, it is found that the hybrid made of G/CNTs in ratio of 10:1 efficiently captures and quenches the free radicals. The waterborne polymer composites containing 1 wt% of hybrid G/CNT are synthesized by in situ miniemulsion free radical polymerization using a water soluble initiator. However, due to excellent efficiency to capture free radicals, the polymerization performed using water soluble initiators in the presence of 10:1 G/CNT filler is hindered. This is resolved by physical separation of the free radicals and the scavenging materials within different phases by use of oil soluble initiator. The resulting polymer composites, beside having excellent mechanical resistance, present exceptional stability under accelerated aging conditions during 400 h, suppressing almost completely the UV photodegradation. This is attributed to the efficient radical scavenging of the G/CNTs hybrid filler distributed within polymer matrix, resulting in high‐performance UV protective waterborne composite coatings.

The combination of graphene (G) and multi-walled carbon nanotubes (MWCNTs) creates three-dimensional hybrid structures particularly suitable as next-generation electrical interface materials. Nevertheless, efficient mixing of the nanopowders is challenging, unless previous disaggregation and eventual surface modification of both is reached. To avoid use of solvents and multistep purification process for synthesis of stable G/MWCNTs hybrids, herein, a novel dry method based on an air sonication process was used. Taking advantage from the vigorous turbulent currents generated by powerful ultrasonication in air that induces strong thermal convection or radiation to and from the particles, it simultaneously ensures disentanglement of the large MWCNT bundles and G exfoliation and their only mild surface modifications. By changing the ratio between MWCNTs and G, a range of hybrids was obtained, different in surface morphology and chemistry. These hybrids have shown great potential as sensing material for designing mass-based sensors for toxic gases and chemiresistor for vapors detection.

Polymer composites based on graphene/carbon nanotubes (G/CNT) and reduced graphene oxide/carbon nanotubes (rGO/CNT) were synthetized by in‐situ miniemulsion polymerization containing 1 wt% hybrid filler with different ratio of G and CNT (10:1, 1.1, 1:10). From the hybrid aqueous dispersions obtained in that way polymer films were spontaneously formed at ambient conditions by water evaporation. The effect of the type of the graphene filler, G or rGO, on the properties and performance of polymer composites was studied. It was shown that G/CNT based composites presented improved morphology of the film due to better distribution of the filler and more organized structure of the film than that of rGO/CNT composites. The surface of the film was much smoother indicating more deepen filler within the polymer. Consequently, the G/CNT/polymer composites presented one order of magnitude increased Young's moduli and 60% lower water uptake than the neat polymer. Even though rGO/CNT/polymer composites presented also improved mechanical resistance, their water resistance was compromised probably due to the presence of hydrophilic functional groups that facilitated the water diffusion within the film.