Grafting of acrylic acid onto microwave plasma-treated polytetrafluoroethylene (PTFE) substrates

Abstract

Polytetrafluoroethylene (PTFE) has limited use in biomedical applications due to its poor wettability and low adhesion strength. Enhancing these properties through modification via plasma treatment coupled with grafting can further improve its surface properties ideal for biomedical applications. In this study, hydrophilic PTFE samples were successfully realized using a modified 2.45 GHz microwave oven as the plasma treatment device followed by grafting copolymerization using acrylic acid (AAc). This resulted to an increase in surface free energy (SFE) where samples subjected to air plasma treatment and AAc grafting exhibited the largest increase in SFE of 58 mJ m−2 compared to 17 mJ m−2 for the untreated samples. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed new functional groups in the O1s and C1s regions of PTFE after plasma treatment and grafting. Atomic force microscopy analysis showed increase in surface roughness with the largest value of 67.7 nm found in air plasma-treated and grafted samples compared to 20.9 nm for the untreated PTFE sample. The plasma-treated and grafted PTFE surfaces did not exhibit hydrophobic recovery during a 7 d observation period as compared to plasma-treated samples only. The effective combination of plasma treatment and grafting process would broaden potential applications of PTFE as a biomaterial.

Recent Advances in Surface Activation of Polytetrafluoroethylene (PTFE) by Gaseous Plasma Treatments

“…The moderately hydrophilic character of the PTFE substrates with water contact angles of about 50° was observed by Valerio et al [ 25 ]. The original WCA was 118°.…”

“…No hydrophobic recovery was observed for up to a week of aging at ambient conditions. Unlike Carbone et al [ 17 ], who also used an MW discharge, the plasma sustained by Valerio et al [ 25 ] was rich in OH, H and O radicals since it was contained in a glass chamber at low pressure. The molecules or residual atmosphere (predominantly water vapor) were effectively dissociated upon the electron-impact dissociation and interaction with Ar metastables.…”

Ar‐H2O‐NH3 plasma grafting and polymerization of dopamine onto polytetrafluoroethylene to promote heparin immobilization

“…The reactive oxygen species and H radicals was grafted to the PTFE surface to form hydroxyl, carboxyl, or C–H bonds. [ 38–41,45 ] The relative peak area ratio of C‐F 2 on PTFE‐P3 decreased to 60.55%, and the relative peak area ratio of C = O increased to 13.57%. However, its C–C/C–H relative peak area proportion decreased to 15.5%.…”

Current Trends in Biomedical Hydrogels: From Traditional Crosslinking to Plasma-Assisted Synthesis

“…It is often regarded as a better alternative to chemical and other wet-based treatment where it is more environmentally friendly, can be operated at low temperature (<100 • C), and consumes less chemicals, energy, and time [12,13]. Plasma generates highly reactive species to modify the surface by attaching or etching the functional groups at or near a polymeric surface [14][15][16][17][18][19]. Aside from surface modification, the excited species of plasma can generate radicals that can recombine and induce crosslinking of polymers in the liquid phase [20].…”