{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,5]],"date-time":"2026-11-05T16:32:33Z","timestamp":1793896353923,"version":"4.8.0"},"reference-count":44,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2021,12,9]],"date-time":"2021-12-09T00:00:00Z","timestamp":1639008000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004329","name":"Slovenian Research Agency","doi-asserted-by":"publisher","award":["L2-2616"],"award-info":[{"award-number":["L2-2616"]}],"id":[{"id":"10.13039\/501100004329","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004329","name":"Slovenian Research Agency","doi-asserted-by":"publisher","award":["P2-0082"],"award-info":[{"award-number":["P2-0082"]}],"id":[{"id":"10.13039\/501100004329","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>The biocompatibility of body implants made from polytetrafluoroethylene (PTFE) is inadequate; therefore, the surface should be grafted with biocompatible molecules. Because PTFE is an inert polymer, the adhesion of the biocompatible film may not be appropriate. Therefore, the PFTE surface should be modified to enable better adhesion, preferably by functionalization with amino groups. A two-step process for functionalization of PTFE surface is described. The first step employs inductively coupled hydrogen plasma in the H-mode and the second ammonia plasma. The evolution of functional groups upon treatment with ammonia plasma in different modes is presented. The surface is saturated with nitrogen groups within a second if ammonia plasma is sustained in the H-mode at the pressure of 35 Pa and forward power of 200 W. The nitrogen-rich surface film persists for several seconds, while prolonged treatment causes etching. The etching is suppressed but not eliminated using pulsed ammonia plasma at 35 Pa and 200 W. Ammonia plasma in the E-mode at the same pressure, but forward power of 25 W, causes more gradual functionalization and etching was not observed even at prolonged treatments up to 100 s. Detailed investigation of the XPS spectra enabled revealing the surface kinetics for all three cases.<\/jats:p>","DOI":"10.3390\/polym13244301","type":"journal-article","created":{"date-parts":[[2021,12,9]],"date-time":"2021-12-09T21:46:58Z","timestamp":1639086418000},"page":"4301","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":18,"title":["Rapid Functionalization of Polytetrafluorethylene (PTFE) Surfaces with Nitrogen Functional Groups"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3782-6001","authenticated-orcid":false,"given":"Alenka","family":"Vesel","sequence":"first","affiliation":[{"name":"Department of Surface Engineering, Jo\u017eef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1366-9147","authenticated-orcid":false,"given":"Rok","family":"Zaplotnik","sequence":"additional","affiliation":[{"name":"Department of Surface Engineering, Jo\u017eef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3959-776X","authenticated-orcid":false,"given":"Gregor","family":"Primc","sequence":"additional","affiliation":[{"name":"Department of Surface Engineering, Jo\u017eef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3529-3371","authenticated-orcid":false,"given":"Miran","family":"Mozeti\u010d","sequence":"additional","affiliation":[{"name":"Department of Surface Engineering, Jo\u017eef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0502-8315","authenticated-orcid":false,"given":"Tadeja","family":"Katan","sequence":"additional","affiliation":[{"name":"Institute for Chemistry and Technology of Biobased Systems, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rupert","family":"Kargl","sequence":"additional","affiliation":[{"name":"Institute for Chemistry and Technology of Biobased Systems, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8569-1642","authenticated-orcid":false,"given":"Tamilselvan","family":"Mohan","sequence":"additional","affiliation":[{"name":"Institute for Chemistry and Technology of Biobased Systems, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9189-0242","authenticated-orcid":false,"given":"Karin Stana","family":"Kleinschek","sequence":"additional","affiliation":[{"name":"Institute for Chemistry and Technology of Biobased Systems, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,12,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"304","DOI":"10.3349\/ymj.2001.42.3.304","article-title":"Calcification comparison of polymers for vascular graft","volume":"42","author":"Park","year":"2001","journal-title":"Yonsei Med. J."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1016\/j.actbio.2017.10.038","article-title":"Transmural capillary ingrowth is essential for confluent vascular graft healing","volume":"65","author":"Pennel","year":"2018","journal-title":"Acta Biomater."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"486","DOI":"10.1016\/j.jinf.2010.03.023","article-title":"Bacterial translocation across ePTFE vascular graft surfaces","volume":"60","author":"Narasimhan","year":"2010","journal-title":"J. Infect."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"495","DOI":"10.1007\/s13239-020-00482-y","article-title":"Considerations in the development of small-diameter vascular graft as an alternative for bypass and reconstructive surgeries: A review","volume":"11","author":"Obiweluozor","year":"2020","journal-title":"Cardiovasc. Eng. Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"217","DOI":"10.4161\/org.6.4.13407","article-title":"Tubular silk scaffolds for small diameter vascular grafts","volume":"6","author":"Lovett","year":"2010","journal-title":"Organogenesis"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Komoto, D., Ikeda, R., Furuike, T., and Tamura, H. (2018). Preparation of chitosan-coated poly(L-lactic acid) fibers for suture threads. Fibers, 6.","DOI":"10.3390\/fib6040084"},{"key":"ref_7","first-page":"259","article-title":"Sodium alginate\/heparin composites on PVC surfaces inhibit the thrombosis and platelet adhesion: Applications in cardiac surgery","volume":"6","author":"Gao","year":"2013","journal-title":"Int. J. Clin. Exp. Med."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"915","DOI":"10.1166\/jbt.2014.1262","article-title":"Covalent grafting of chitosan on plasma-treated polytetrafluoroethylene surfaces for biomedical applications","volume":"4","author":"Vaz","year":"2014","journal-title":"J. Biomater. Tissue Eng."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"100412","DOI":"10.1016\/j.mtchem.2020.100412","article-title":"ePTFE functionalization for medical applications","volume":"20","author":"Roina","year":"2021","journal-title":"Mater. Today Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1111\/j.1525-1594.1995.tb02241.x","article-title":"Nonthrombogenic polymer vascular prosthesis","volume":"19","author":"Nojiri","year":"1995","journal-title":"Artif. Organs"},{"key":"ref_11","first-page":"425","article-title":"Infrainguinal ePTFE vascular graft with bioactive surface heparin bonding-First clinical results","volume":"46","author":"Walluscheck","year":"2005","journal-title":"J. Cardiovasc. Surg."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"67","DOI":"10.1002\/jbm.a.33138","article-title":"Accelerated neovascularization and endothelialization of vascular grafts promoted by covalently bound laminin type 1","volume":"99A","author":"Williams","year":"2011","journal-title":"J. Biomed. Mater. Res. A"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1016\/j.ejvs.2014.12.008","article-title":"Nanotopography and plasma treatment: Redesigning the surface for vascular graft endothelialisation","volume":"49","author":"Chong","year":"2015","journal-title":"Eur. J. Vasc. Endovasc. Surg."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"619","DOI":"10.1163\/156856209X426439","article-title":"Biomimetic fluorocarbon surfactant polymers reduce platelet adhesion on PTFE\/ePTFE surfaces","volume":"20","author":"Wang","year":"2009","journal-title":"J. Biomater. Sci. Polym. Ed."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2258","DOI":"10.3390\/ma8052258","article-title":"Low-pressure H2, NH3 microwave plasma treatment of polytetrafluoroethylene (PTFE) powders: Chemical, thermal and wettability analysis","volume":"8","author":"Hunke","year":"2015","journal-title":"Materials"},{"key":"ref_16","first-page":"e54272","article-title":"Wet chemistry and peptide immobilization on polytetrafluoroethylene for improved cell-adhesion","volume":"114","year":"2016","journal-title":"J. Vis. Exp."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"891","DOI":"10.1021\/acsabm.9b00970","article-title":"Promotion of endothelial cell adhesion and antithrombogenicity of polytetrafluoroethylene by chemical grafting of chondroitin sulfate","volume":"3","author":"Ma","year":"2020","journal-title":"ACS Appl. Bio Mater."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"65","DOI":"10.1016\/j.radphyschem.2018.03.011","article-title":"Primary-amine surface functionalization of polytetrafluoroethylene films by radiation grafting of aminated polyacryloyl chloride","volume":"149","author":"Ruiz","year":"2018","journal-title":"Radiat. Phys. Chem."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1579","DOI":"10.3938\/jkps.50.1579","article-title":"Modification of expanded polytetrafluoroethylene surface with low-energy nitrogen-ion-beam irradiation","volume":"50","author":"Choi","year":"2007","journal-title":"J. Korean Phys. Soc."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"699","DOI":"10.1016\/S0142-9612(99)00231-8","article-title":"Use of plasma glow for surface-engineering biomolecules to enhance bloodcompatibility of Dacron and PTFE vascular prosthesis","volume":"21","author":"Chandy","year":"2000","journal-title":"Biomaterials"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1016\/j.apsusc.2014.01.048","article-title":"Bioactive surface modifications on inner walls of poly-tetra-fluoro-ethylene tubes using dielectric barrier discharge","volume":"296","author":"Cho","year":"2014","journal-title":"Appl. Surf. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"373","DOI":"10.2494\/photopolymer.31.373","article-title":"Novel DLC coating technique on an inner-wall of extended polytetrafluoroethylene vascular grafts using methane plasma produced by AC HV discharge","volume":"31","author":"Nakatani","year":"2018","journal-title":"J. Photopolym. Sci. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"307","DOI":"10.2494\/photopolymer.30.307","article-title":"Surface modification of fluorine-containing polymers by atmospheric pressure plasma jet with negative substrate biasing","volume":"30","author":"Nagatsu","year":"2017","journal-title":"J. Photopolym. Sci. Technol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"146128","DOI":"10.1016\/j.apsusc.2020.146128","article-title":"Plasma treatment in air at atmospheric pressure that enables reagent-free covalent immobilization of biomolecules on polytetrafluoroethylene (PTFE)","volume":"518","author":"Bilek","year":"2020","journal-title":"Appl. Surf. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"293001","DOI":"10.1088\/1361-6463\/aa748a","article-title":"New developments in surface functionalization of polymers using controlled plasma treatments","volume":"50","author":"Vesel","year":"2017","journal-title":"J. Phys. D Appl. Phys."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Primc, G. (2020). Recent advances in surface activation of polytetrafluoroethylene (PTFE) by gaseous plasma treatments. Polymers, 12.","DOI":"10.3390\/polym12102295"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"147356","DOI":"10.1016\/j.apsusc.2020.147356","article-title":"Effect of VUV radiation and reactive hydrogen atoms on depletion of fluorine from polytetrafluoroethylene surface","volume":"533","author":"Lojen","year":"2020","journal-title":"Appl. Surf. Sci."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Resnik, M., Zaplotnik, R., Mozetic, M., and Vesel, A. (2018). Comparison of SF6 and CF4 Plasma Treatment for Surface Hydrophobization of PET Polymer. Materials, 11.","DOI":"10.3390\/ma11020311"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1700105","DOI":"10.1002\/ppap.201700105","article-title":"E- and H-mode transition in a low pressure inductively coupled ammonia plasma","volume":"15","author":"Zaplotnik","year":"2018","journal-title":"Plasma Process. Polym."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"045006","DOI":"10.1088\/0963-0252\/25\/4\/045006","article-title":"Quantification of the VUV radiation in low pressure hydrogen and nitrogen plasmas","volume":"25","author":"Fantz","year":"2016","journal-title":"Plasma Sources. Sci. Technol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1002\/ecj.11844","article-title":"Surface modification of PTFE using low-energy nitrogen ion irradiation: Improvement in adhesive strength on modification of deep modifying layer","volume":"99","author":"Takata","year":"2016","journal-title":"Electron. Commun. Jpn."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"385","DOI":"10.1002\/sia.1065","article-title":"Plasma modification of PTFE surfaces. Part I: Surfaces immediately following plasma treatment","volume":"31","author":"Wilson","year":"2001","journal-title":"Surf. Interface Anal."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"493","DOI":"10.1002\/ppap.200500010","article-title":"Selected effect of the ions and the neutrals in the plasma treatment of PTFE surfaces: An OES-AFM-contact angle and XPS study","volume":"2","author":"Vandencasteele","year":"2005","journal-title":"Plasma Process. Polym."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"103305","DOI":"10.1063\/1.1900290","article-title":"Atomic hydrogen densities in capacitively coupled very high-frequency plasmas in H2: Effect of excitation frequency","volume":"97","author":"Jolly","year":"2005","journal-title":"J. Appl. Phys."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"11554","DOI":"10.1021\/la701126t","article-title":"Determination of amine and aldehyde surface densities: Application to the study of aged plasma treated polyethylene films","volume":"23","author":"Ghasemi","year":"2007","journal-title":"Langmuir"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"386","DOI":"10.1002\/ppap.200700134","article-title":"Surface radical detection an NH3-plasma treated polymer surfaces using the radical scavenger NO","volume":"5","author":"Finke","year":"2008","journal-title":"Plasma Process. Polym."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"12490","DOI":"10.1021\/jp011607k","article-title":"Ammonia RF\u2212plasma on PTFE surfaces: Chemical characterization of the species created on the surface by vapor\u2212phase chemical derivatization","volume":"105","author":"Chevallier","year":"2001","journal-title":"J. Phys. Chem. B"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1007\/s00216-009-3233-7","article-title":"Determination of accessible amino groups on surfaces by chemical derivatization with 3,5-bis(trifluoromethyl)phenyl isothiocyanate and XPS\/NEXAFS analysis","volume":"396","author":"Graf","year":"2010","journal-title":"Anal. Bioanal. Chem."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1800160","DOI":"10.1002\/ppap.201800160","article-title":"XPS investigation on the reactivity of surface imine groups with TFAA","volume":"16","author":"Kehrer","year":"2019","journal-title":"Plasma Process. Polym."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"953","DOI":"10.1002\/ppap.201500115","article-title":"Innovative and established strategies for the surface analysis of nitrogen and oxygen-rich plasma polymer films by XPS: An introductory guide","volume":"12","author":"Unger","year":"2015","journal-title":"Plasma Process. Polym."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1213","DOI":"10.1002\/ppap.201600210","article-title":"Critical remarks on chemical derivatization analysis of plasma-treated polymer surfaces and plasma polymers","volume":"13","author":"Klages","year":"2016","journal-title":"Plasma Process. Polym."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1002\/ppap.201200142","article-title":"Some remarks on chemical derivatization of polymer surfaces after exposure to nitrogen-containing plasmas","volume":"10","author":"Klages","year":"2013","journal-title":"Plasma Process. Polym."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"390","DOI":"10.1016\/j.apsusc.2017.04.127","article-title":"Determination of NH2 concentration on 3-aminopropyl tri-ethoxy silane layers and cyclopropylamine plasma polymers by liquid-phase derivatization with 5-iodo 2-furaldehyde","volume":"414","author":"Manakhov","year":"2017","journal-title":"Appl. Surf. Sci."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"532","DOI":"10.1002\/ppap.201300177","article-title":"Optimization of cyclopropylamine plasma polymerization toward enhanced layer stability in contact with water","volume":"11","author":"Manakhov","year":"2014","journal-title":"Plasma Process. Polym."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/13\/24\/4301\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:43:58Z","timestamp":1760168638000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/13\/24\/4301"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,12,9]]},"references-count":44,"journal-issue":{"issue":"24","published-online":{"date-parts":[[2021,12]]}},"alternative-id":["polym13244301"],"URL":"https:\/\/doi.org\/10.3390\/polym13244301","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,12,9]]}}}