Improving mechanical properties and durability of polyether sealant in prefabricated buildings with titanium dioxide and graphene

The silane-modified polyether sealant is widely applied to fill the gaps between external walls in prefabricated buildings and to bear the deformation of joints. However, the weak tensile strength and poor ultraviolet and moisture resistance of sealant lead to severe degradation, posing threat to the building waterproofing and safety. To address the problems, titanium dioxide and graphene were adopted to improve the mechanical properties and durability of sealant. The tack-free time, tensile properties, ultraviolet resistance, and hydrophobic performance of pristine and modified sealant were investigated and the enhancement and erosive resistance mechanisms of modified sealant were revealed by microscale characterization. Results indicated that modified sealant with low content of titanium dioxide had greater tensile strength and ultraviolet resistance. The crystalline form of titanium dioxide and produced Si-O bond enhanced the ultraviolet resistance. Moreover, the 0.8% graphene-modified sealant possessed superior moisture resistance with 23% increased contact angle. Graphene increased the surface roughness and generated π-conjugated structure, improving sealant hydrophobicity. It is revealed that the enhanced properties were ascribed to the spatial structure of fillers and chemical bond energy. This work provides a novel sealant with high ultraviolet resistance and hydrophobicity, facilitating the development of durable and low-maintenance prefabricated buildings.