Silicone elastomers with a small MWCNTs content: Thermal properties, surface profile and hydrophobicity

MWCNTs/PDMS nanocomposites with a small amount of MWCNTs (0.25, 0.5, 1.5 and 2.5 wt.%) were prepared by the solution-casting and curing techniques. The structural properties of the fabricated elastomers were characterized using FTIR and Raman spectroscopies, indicating an interaction between the nanofiller and the polymer through physical bonding. The characteristic peaks of MWCNTs are not visible in the XRD spectra of the obtained polymer nanocomposites due to their lower content and surrounding by the matrix. Thermal decomposition in air was performed to determine the effect of the low-loaded MWCNTs on the thermal-oxidative stability of nanocomposites. Differential thermogravimetric (DTG) analysis showed a notable shift towards higher temperatures at approximately 42 °C, 78 °C, and 33 °C for the first three DTG peaks maxima in the case of the 2.5MWCNTs/PDMS nanocomposite compared to neat PDMS. The morphology and surface roughness were investigated by SEM and a 3D non-contact optical surface profilometer. The incorporation of 2.5 wt. % MWCNTs into the PDMS matrix results in an increase in the water contact angle from 95.6 ± 4.2° to 112.4 ± 2.8° and a decrease in the apparent surface free energy from 28.0 ± 3.9 mJ/m 2 to 20.8 ± 2.4 mJ/m 2 compared to neat PDMS, demonstrating that the MWCNTs/PDMS nanocomposites are more hydrophobic. Studies were conducted on the stability of surface properties (hydrophobicity, roughness) over time under relevant environmental conditions. This paper shows that the surface topology, wettability and thermal properties of PDMS can be tuned with reasonable confidence using a small amount of MWCNTs. • MWCNTs/PDMS elastomeric nanocomposites were fabricated by the solution-casting and curing method; • MWCNTs/PDMS nanomaterials exhibit improved thermal-oxidative stability even at low nanofiller content (0.25 – 2.5 wt.%); • Morphological analysis shows that MWCNTs are homogeneously dispersed in the silicone matrix; • The 2.5MWCNTs/PDMS nanocomposite possesses hydrophobic properties and the water contact angle reaches 112°, while the surface roughness (Ra) value is 10.1±3.2 μm; • The findings will be useful for researchers to tailor properties Sylgard-184 silicone elastomer with MWCNTs.