Hydrophilic modification of expanded polytetrafluoroethylene (ePTFE) by atmospheric pressure glow discharge (APG) treatment

ePTFE has been used in biomedical applications such as artificial blood vessels. However, the inherent nature of the highly hydrophobic ePTFE surface retards tissue ingrowth and wound healing. APG plasma treatment was applied to modify ePTFE tubes from being hydrophobic to being hydrophilic with AAc or PAA. The plasma-pretreated ePTFE tubes were immersed in AAc or PAA solution, then treated with helium-APG plasma. The spectra of FTIR–ATR adopted the appearance of an absorption peak ascribed to carbonyl group, and XPS showed reduced F / C and increased O / C. The water contact angles after treatment were decreased. An SEM image showed that the fibrils of ePTFE tubes were interconnected with each other to form assembled bundles of fibrils. These results indicated the formation of an insoluble polymerized AAc or PAA layer on the ePTFE surface. Polymerization of AAc or PAA began occurring on the surface of ePTFE and then continued within porous structures. The surfaces of ePTFE were more effectively modified by PAA than AAc. The outer surface was more hydrophilic than the inner surface. When the outer tube of ePTFE was wrapped with PTFE film and processed using the same experimental method, a markedly enhanced surface modification on the inner surface, especially with the use of AAc, was observed. AAc was easier to polymerize on the surface of the ePTFE tube, as a result, the hydrophilicity of the inner surface was increased.