Optimizing grafting thickness of zwitterionic sulfobetaine polymer on cross-linked polyethylene surface to reduce friction coefficient

Chung Man Lim, Jiae Seo, Ho Jang, Ji-Hun Seo

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

The purpose of this study involves reducing the friction coefficient of cross-linked polyethylene (CLPE) by optimizing the grafting thickness of zwitterionic poly(2-(methacryloyloxy)ethyl dimethyl-(3-sulfopropyl)ammonium hydroxide) (PMEDSAH) via a photo-induced free radical polymerization process. Cross-sectional TEM images and XPS spectra indicated that the PMEDSAH layers were successfully grafted on the CLPE. The grafting thickness increased when UV-irradiation time, UV-irradiation energy, and MEDSAH monomer concentration increased. The contact angle data indicated that the PMEDSAH layers successfully imparted hydrophilicity (below 20°) on the CLPE surface. The friction coefficient test and the resulting 3-D confocal images confirmed a significant decrease in the friction coefficient with increases in the grafting thickness. A minimum grafting thickness of 200 nm PMEDSAH was required to minimize the friction coefficient in an aqueous medium. However, a PMEDSAH-grafting thickness of approximately 40 nm was sufficient to reveal the minimized friction coefficient in simulated body fluids (ionic buffer solution) due to the salt-induced hydration effect. The results defined the minimum required thickness of PMEDSAH grafting to minimize the friction coefficient on CLPE surface that can potentially be applied for artificial hip joints.

Original languageEnglish
Pages (from-to)102-112
Number of pages11
JournalApplied Surface Science
Volume452
DOIs
Publication statusPublished - 2018 Sep 15

Keywords

  • Cross-linked polyethylene
  • Friction coefficient
  • Grafting thickness
  • Photo-induced grafting
  • Salt-induced hydration
  • Zwitterion

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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