Frozen FIB-SEM reveals the correlation between the interface morphology of damaged PDMS anti icing coating and ice adhesion strength

Research Background and Issues

Silicone elastomers are considered promising anti icing coating materials due to their low ice adhesion strength, but their soft texture and durability of anti icing performance on the surface after wear or cutting have been controversial. Previous research on the effect of surface damage on ice adhesion has yielded inconsistent results, with both reports of enhanced ice adhesion and observations of weakened adhesion. To explain this contradiction from the perspective of interface morphology, the research team used cryo focused ion beam scanning electron microscopy (cryo FIB-SEM) to directly image the contact interface between the damaged polydimethylsiloxane (PDMS) surface and ice droplets.

Experimental methods and key findings

In the study, the PDMS surface was damaged through two methods: cutting and abrasion.

. After milling and imaging the ice PDMS interface using FIB, researchers observed for the first time two states simultaneously: high actual contact area and low actual contact area, depending on the shape of the abrasive surface roughness. In the samples with cutting damage, direct evidence of the degree of ice infiltration into the incision was also obtained. The interface contact morphology can be likened to two wetting states, Cassie Baxter and Wenzel, and these morphological features are associated with the trend of changes in ice adhesion strength.

Implications for polymer additives and the rubber industry

Although this study focuses on silicone elastomer anti icing coatings, the interface contact mechanism revealed has reference value for the field of tires and rubber.

. In tire formula design, reinforcing fillers such as white carbon black indirectly affect the contact state between the surface and external substances by regulating the micro roughness and mechanical properties of the rubber surface. Antioxidants and antioxidants are related to the surface aging and damage evolution of rubber during long-term use, thereby changing the actual contact area. The vulcanization system determines the crosslink density and the softness and hardness of the elastomer, and also affects the interfacial permeability behavior after damage. This study suggests that when evaluating the durability of surface functional coatings or bulk materials of rubber products, damage morphology and interface contact state need to be taken into account, rather than just focusing on initial performance. For the field of tire retreading and recycling, the interface behavior after surface damage may also affect the adhesion and performance of the retreading compound. In the future, characterization methods similar to cryo FIB-SEM may be extended to the study of interfaces between tire rubber surfaces and media such as ice, water, and oil, providing more direct microscopic basis for formula optimization and life prediction.

Information source:Ice‐Droplet and Damaged Elastomer Interfaces: A Closer Look at Contact and Morphology of Anti‐Icing Coatings Using Cryo‐FIB‐SEM， Organized by Herun Chemical.