Described herein are reactors capable of sequentially or simultaneously depositing thin-film polymers onto a substrate by oxidative chemical vapor deposition (oCVD), initiated chemical vapor deposition (iCVD), and plasma-enhanced chemical vapor deposition (PECVD). The single-unit CVD reactors allow for the use of more than one CVD process on the same substrate without the risk of inadvertently exposing the substrate to ambient conditions when switching processes. Furthermore, the ability to deposit simultaneously polymers made by two different CVD processes allows for the exploration of new materials. In addition to assisting in the deposition of polymer films, plasma processes may be used to pretreat substrate surfaces before polymer deposition, or to clean the internal surfaces of the reactor between experiments.