Sized carbon fibers, methods for the manufacture and use thereof, and carbon fiber polymer composites made from such compositions. In particular, sized carbon fibers are manufactured by a method including: contacting a plurality of carbon fibers with a sizing composition to form coated carbon fibers, wherein the sizing composition comprises a polyoxazoline sizing agent, preferably a poly[2-ethyl 2-oxazoline] sizing agent, dissolved in a solvent; and removing the solvent from the coated carbon fibers to form sized carbon fibers comprising the sizing agent.
