Making a Hydrophobic Plastic Device Permanently Hydrophilic

We are looking into the possibilities to replace a glass capillary currently glued into a sampling device with a plastic moulded sampling device (including a plastic capillary part). We face problems with the capillary forces due to the hydrophobicity of the plastics. Do you have any suggestions (other than plasma/corona treatment) how to make the capillary part permanently more hydrophilic and hence reduce the blood suck up time to an acceptable level (< 5 sec)? Blood volume in the region of 15 µL.