Effects of crosslinking, embedded TiO2 particles and extreme aging on PDMS icephobic barriers

Abstract

Using an optimized push test, a polydimethylsiloxane (PDMS) based two-component room temperature vulcanized (RTV-2) silicone rubber (SIR) was tested for its resistance to ice adhesion. The effects of reduced crosslinking of the polymer and embedded titanium dioxide on ice adhesion were also investigated. Both the reduction in crosslinking and the presence of embedded titanium dioxide (TiO2) microparticles greatly improved icephobic properties of the rubber. Subsequently, extreme aging of the rubber was performed in hypochlorous acid (HOCl) at room temperature as a function of reduced crosslinking. In addition, the TiO2/PDMS composite was subjected to acid to evaluate its resistance to ice adhesion after aging. It has been shown that extreme aging essentially eliminated the positive effects of reduced crosslinking and embedded TiO2 particles on ice adhesion. However, embedded TiO2 protected and maintained the icephobic properties of the rubber during extreme aging by about 40% in comparison with the aged unmodified rubber. In the numerical part of this research, Molecular Dynamics (MD) simulations of ice/PDMS interfaces were performed considering the crosslinking effect, presence of TiO2 particles, and extreme aging. The MD simulations supported the experimental observations very well. Most importantly, the effects observed experimentally regarding the icephobic properties of the RTV-2 and their modifications such as reduced crosslinking, TiO2 particles, and aging could be explained in terms of the number of hydrogen bonds present at the PDMS surface.