Are all functionalized products endcapped?

Most products are endcapped but there are a few exceptions. The oxidants, Si-KMnO₄, Si-PCC and Si-PDC are not endcapped for the simple reason that the silanols (free OH groups on the silica surface) are needed to ensure optimal efficiency of the material. They retain the by-products generated during the reaction, considerably simplifying the work-up step.