How is a C18 HPLC column made?

Question

How is a C18 HPLC column made?

Answer 1

Typically they're made by reacting an appropriate silane reagent with silica particles, and stuffing the silica into the tube for the column.  The silane reagent would be an alcoxysilane (triethoxysilane) with a C18 chain.

There's a lot to get right to make a good column - reaction conditions, choice of starting reagent, size of the silica particles, packing conditions, etc.