In advanced composite materials, interfacial bonding strength often determines the upper limit of overall performance. Although phenyltrimethoxysilane (PTMS) is not as highly reactive as amino or epoxy silanes, its unique phenyl structure provides irreplaceable advantages in specific systems.

When used for the surface treatment of fillers such as glass fiber, quartz fiber, or nano-silica, PTMS forms a siloxane layer after hydrolysis that firmly anchors to inorganic surfaces. The phenyl groups extend outward and interact with aromatic resins—such as epoxy, polyimide, and polyphenylene ether—through π–π interactions or van der Waals forces, improving interfacial compatibility. In low-dielectric composites used for high-frequency circuit substrates, PTMS-modified fillers can effectively reduce dielectric constant and loss while maintaining mechanical strength.

In addition, in ablative composites such as rocket nozzles, PTMS participates in forming ceramic precursors that convert into SiC- and carbon-containing char layers at high temperatures, providing additional thermal protection. The resulting pyrolysis products are denser and exhibit improved oxidation resistance.

It can therefore be seen that phenyltrimethoxysilane is not only a modifier for conventional silicone materials, but also an important contributor to achieving lightweight, high-performance, and functional advanced composites.