High throughput carbon fiber surface modification

A method of modifying a surface of carbon fiber having a functional moiety, said method comprising steps of:

• (a) contacting in a reactor, in the absence of a solvent, the surface of the carbon fiber with a vapor phase of a silane capable of covalent bonding to the functional moiety on the surface of the carbon fiber or depositing via condensation on the surface of the carbon fiber;
• wherein said contacting step is conducted in a sealed container under a vacuum pressure ranging from the vapor pressure of the silane to up to about 101325 Pa for a sufficient time to covalently bond at least some of said silane to the functional moiety on the surface of the carbon fiber;
• and
• (b) exposing the carbon fiber produced in step (a) to a temperature of from about 25° C. to about 200° C. for a period of from about 1 minute to about 96 hours to crosslink at least some of the silane on the surface of the carbon fiber;
• wherein
• i) the carbon fiber and the reactor each have a volume and a ratio of the volume of the carbon fiber to the reactor volume is from about 0.1 to about 0.6, the contacting step is carried out at a pH of from about 5 to about 7 and the temperature of the exposing step is from about 75° C. to about 125° C., or
• ii) further comprising a step of condensing the vapor phase at the end of the contacting step and prior to the exposing step by equilibrating the vapor phase and the carbon fiber to a pressure above the vapor pressure of the silane to condense at least some liquid silane onto the surface of the carbon fiber and said exposing step crosslinks at least some of the silane groups covalently bound to the surface of the carbon fibers and at least some of the liquid silane condensed onto the surface of the carbon fiber.