Symposium on Ion-Beam-Based Nanofabrication held at the 2007 MRS Spring Meeting -- APR 10-12, 2007 -- San Francisco, CAWOS: 000250475100012Ultra High Molecular Weight Polyethylene (UHMWPE) samples were implanted with metal and metal-gas hybrid ions (Ag, Ag+N, C+H, C+H+Ar, Ti+O) by using improved MEVVA Ion implantation technique [1,2]. An extraction voltage of 30 kV and influence of 1017 ions/cm2 were attempted in this experiment. to change their surface morphologies in order to understand the effect of ion implantation on the surface properties of UHMWPEs. Characterizations of the implanted samples with RBS, ATR - FTIR, spectra were compared with the un-implanted ones. Implanted and unimplanted samples were also thermally characterized by TGA and DSC. It was generally observed that C-H bond concentration seemed to be decreasing with ion implantation and the results indicated that the chain structure of UHMWPE were changed and crosslink density and polymer crystallinity were increased compared to unimplanted ones resulting in increased hardness. It was also observed that nano size cracks (approx. 10nm) were significantly disappeared after Ag implantation, which also has an improved antibacterial effect. Contact angle measurements showed that wettability of samples increased with ion implantation. Results showed that metal and metal+gas hybrid ion implantation could be an effective way to improve the surface properties of UHMWPE to be used in hip and knee prosthesis.Center for Irradiation of Materials, Alabama AM UniversityThis work was supported by the Center for Irradiation of Materials, Alabama A&M University

Budak, Satilmis

Chhay, Bopha

Eltem, Rengin

Ezdesir, Ayhan

Ila, Daryush

Kaya, Nusret

Muntele, C.

Nikolaev, Alexey

Oks, Efim

Oztarhan, Ahmet

Tek, Zekai

Tihminlioglu, Funda

Urkac, Emel Sokullu

Yenigul, Mesut

Zimmerman, Robert

MRS Proceedings

Ion-Beam-Based Nanofabrication; San Francisco, CA; United States; 10 April 2007 through 12 April 2007Ultra High Molecular Weight Polyethylene (UHMWPE) samples were implanted with metal and metal-gas hybrid ions (Ag, Ag+N, C+H, C+H+Ar, Ti+O) by using improved MEVVA Ion implantation technique [1,2]. An extraction voltage of 30 kV and influence of 1017 ions/cm2 were attempted in this experiment, to change their surface morphologies in order to understand the effect of ion implantation on the surface properties of UHMWPEs. Characterizations of the implanted samples with RBS , ATR - FTIR, spectra were compared with the un-implanted ones . Implanted and unimplanted samples were also thermally characterized by TGA and DSC. It was generally observed that C-H bond concentration seemed to be decreasing with ion implantation and the results indicated that the chain structure of UHMWPE were changed and crosslink density and polymer crystallinity were increased compared to unimplanted ones resulting in increased hardness. It was also observed that nano size cracks (approx.10nm) were significantly disappeared after Ag implantation, which also has an improved antibacterial effect. Contact angle measurements showed that wettability of samples increased with ion implantation. Results showed that metal and metal+gas hybrid ion implantation could be an effective way to improve the surface properties of UHMWPE to be used in hip and knee prosthesis.Center for Irradiation of Materials, Alabama A&M Universit

Öztarhan, Ahmet

Sokullu Urkaç, Emel

Yenigül, Mesut

Tıhmınlıoğlu, Funda

Ezdeşir, Ayhan

Budak, Satılmış

DSpace@IZTECH

Modification of surface morphology of UHMWPE for biomedical implants

WOS: 000250475100012Symposium on Ion-Beam-Based Nanofabrication held at the 2007 MRS Spring Meeting -- APR 10-12, 2007 -- San Francisco, CAUltra High Molecular Weight Polyethylene (UHMWPE) samples were implanted with metal and metal-gas hybrid ions (Ag, Ag+N, C+H, C+H+Ar, Ti+O) by using improved MEVVA Ion implantation technique [1,2]. An extraction voltage of 30 kV and influence of 1017 ions/cm2 were attempted in this experiment. to change their surface morphologies in order to understand the effect of ion implantation on the surface properties of UHMWPEs. Characterizations of the implanted samples with RBS, ATR - FTIR, spectra were compared with the un-implanted ones. Implanted and unimplanted samples were also thermally characterized by TGA and DSC. It was generally observed that C-H bond concentration seemed to be decreasing with ion implantation and the results indicated that the chain structure of UHMWPE were changed and crosslink density and polymer crystallinity were increased compared to unimplanted ones resulting in increased hardness. It was also observed that nano size cracks (approx. 10nm) were significantly disappeared after Ag implantation, which also has an improved antibacterial effect. Contact angle measurements showed that wettability of samples increased with ion implantation. Results showed that metal and metal+gas hybrid ion implantation could be an effective way to improve the surface properties of UHMWPE to be used in hip and knee prosthesis.This work was supported by the Center for Irradiation of Materials, Alabama A;M University.Center for Irradiation of Materials, Alabama AM Universit

Ege University Institutional Repository

DSpace@IZTECH Institutional Repository

Modification of Surface Morphology of UHMWPE for Biomedical Implants 
 
Ahmet Oztarhan , Emel Sokullu Urkac , Nusret Kaya , Mesut Yenigul , Funda 
Tihminlioglu , Ayhan Ezdesir , Robert Zimmerman , Satilmis Budak , C Muntele , 
Bopha Chhay , Daryush Ila , Efim Oks , Alexey Nikolaev , Zekai Tek , and Rengin 
Eltem
1 1 1 2
3 4 5 5 5
5 5 6 6 7
1
1Bioengineering, Ege University, Bornova, Izmir, 35100, Turkey 
2Chemical engineering, Ege University, Bornova, Izmir, 35100, Turkey 
3Chemical engineering, Izmir Institute of Technology, Izmir, 35000, Turkey 
4Petkim, Izmir, 35000, Turkey 
5Alabama A&M University, Huntsville, AL, 35762 
6High Current Electronics Institute, Tomsk, 634055, Russian Federation 
7Celal Bayar University, Manisa, 45000, Turkey
 
Abstract 
 
Ultra High Molecular Weight Polyethylene (UHMWPE)  samples were implanted with 
metal and  metal-gas  hybrid  ions (Ag, Ag+N, C+H, C+H+Ar, Ti+O ) by  using 
improved MEVVA  Ion implantation  technique [1,2] . An extraction voltage of 30 kV 
and influence of 1017 ions/cm2 were attempted in this experiment. to change their 
surface morphologies in order to understand the effect of  ion  implantation on the surface 
properties of UHMWPEs. Characterizations  of  the implanted   samples  with RBS ,  
ATR - FTIR, spectra   were  compared  with   the  un-implanted ones . Implanted  and 
unimplanted samples were also thermally characterized by  TGA and DSC.  It was 
generally observed that  C–H bond concentration seemed to be decreasing with ion 
implantation  and the results indicated that  the chain structure of UHMWPE   were 
changed and  crosslink density and polymer crystallinity were  increased  compared to  
unimplanted  ones resulting  in increased hardness. It was also observed that nano size 
cracks (approx.10nm) were significantly  disappeared   after  Ag   implantation, which   
also  has an improved  antibacterial effect .  Contact angle  measurements  showed  that 
wettability  of samples  increased with ion implantation.  Results showed  that metal and 
metal+gas hybrid  ion implantation could be an effective way to improve the surface 
properties of  UHMWPE  to be used in hip and knee prosthesis. 
 
1. Introduction 
 
Ultra High Molecular Weight Polyethylene (UHMWPE) has been commonly used for 
acetabular cup of total hip joint replacement as it has  densely packed linear polyethylene 
chains, which gives improved mechanical properties.  However the wear of UHMWPE  
against the articulating metal part  and wear debris generated at the surface is recognized 
as the major cause of loosening and failure of the total joint replacement. Recent studies 
show that increasing the cross-linking in the polyethylene significantly reduces wear 
leading to more durable acetabular components and increasing the lifetime of an implant . 
Increasing the cross-link density of UHMWPE in which UHMWPE is irradiated in air at 
an elevated temperature with a high-dose-rate electron beam  or a  common approach is 
Mater. Res. Soc. Symp. Proc. Vol. 1020 © 2007 Materials Research Society 1020-GG05-03
to cross-link the polymer by gamma irradiation, which improves markedly the wear 
resistance of the polymer but with changed bulk properties [3]. In this work, we tried to 
change the surface morphology of UHMWPE  by low energy metal and metal+gas hybrid 
ion implantation by MEVVA , with an expectation of improving surface mechanical 
properties, and promoting antibacterial effect without changing the bulk properties of 
UHMWPE . 
 
2. Experimental 
Samples with medical grade GUR 1020 - Type 1 - Ultra High Molecular Weight 
Polyethylene (UHMWPE - , Hipokrat Co.) with a density of  945 kg/m3 were used .  Disk 
samples with a diameter of  30mm and thickness of 4mm were polished down to  about 
surface roughness of  95 (nm) Ra. Samples were implanted with  Ag, Ag+N, C+H, 
C+H+Ar, Ti+O  ions by using MEVVA ion implanter with a fluence of  1017 ion/cm2  and 
extraction voltage of 30 kV. ATR- FTIR chemical characterization analysis was used to 
see if any new chemical bonds  formed 2 microns deep at the surface. Thermo Nicolet 
Nexus 670 model FTIR with Smart DuraSampllR 3 Bounce diamond HATR (3 reflection 
diamond ATR) and OMNIC software were used. DSC (Differential Scanning 
Calorimeter) SHIMADZU DT-50 and the TGA (Thermo Gravimetric Analyzer) 
SHIMADZU DT-51  were used for thermal analysis of implanted and unimplanted 
samples. The analyses were performed in a dry nitrogen atmosphere. Aluminum cells 
were used for analysis of the polymers. The temperatures of the sample cells were 
increased by 10 0C/min. The total heat of melting ΔH (the area under the endotherm-
DSC) was determined and, knowing the total heat of fusion of 100% crystalline 
UHMWPE (ΔHf = 293.6 J/g), the percentage crystallinity was calculated as 
100( ΔH/ΔHf)  [4]. Scanning electron microscopy (Philips XL-305 FEG – SEM) was 
used  to examine the  surfaces of unimplanted and Ag and Ag+N implanted samples.  
Atomic force microscopy (AFM) was used to investigate the surface morphology of 
unimplanted and  implanted UHMWPE. A Digital Instrument- MultiModeSPM apparatus 
was used to determine the surface roughness. The durometer hardness test was used to 
measure the relative hardness of the samples. The test method is based on the penetration 
of a specified indenter forced into the material under specified conditions. A Shore 
hardness tester ZWICk/Roell (HPE) under 50N force was used. The contact angle of 
wateron unimplanted and implanted UHMWPE surfaces was measured with a Krüss-G10 
goniometer. The antibacterial activities of  unimplanted  and Ag implanted UHMWPE 
samples of 5mm diameter and 3mm thickness were examined against “Staphylococcus 
Aureus”   by "Agar Disk Diffusion Method". After 24 hours bacteria reduction was100%.  
 
3. Results and Discussions 
RBS graphs, are used as an analytical tool to measure some of the implanted elements  
(C, Ag, Ti, N, O) concentration of the sample surfaces. For example, Figure 1,2 show  
Ag, Ti, C , N and O  ions, which  can be detected up to 42 +15 nm underneath the 
surface. All spectra show an O peak, which is believed to be caused by oxidation and 
some small peaks by  the residual air in the Vacuum chamber. Oxygen uptake takes place 
once the ion bombarded polymer sample was exposed to the air [5].  
 
 
  
 
 
 
 
 
 
 
 
 
       Figure.1  RBS Spectrum of Ag + N                      Figure.2  RBS Spectrum of  Ti + O 
       Implanted UHMWPE                                            Implanted UHMWPE 
 
The characteristic absorption bands for the CH2  bonds appear in the 2900–2840, 
1460–1370 and 740–720 cm−1 regions [6]. The transmission ATR analysis of the 
unimplanted  and   implanted samples confirms the  C–H  bond breaking since the C–H 
stretching (at 2847 cm−1)  bond  peaks of the pure UHMWPE sample disappear after ion 
implantation (figures. 3,4,5).  
 
UHMWPE+Ag
UHMWPE
 25
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 45
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 55
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 65
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 75
 80
 85
 90
 95
 100
 105
%
Tr
a
n
sm
itta
n
ce
 1000   1500   2000   2500   3000   3500  
Wavenumbers (cm-1)
 Figure.3   FTIR spectra of Ag Implanted UHMWPE 
 
Ag+N
BLANK
 25
 30
 35
 40
 45
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 65
 70
 75
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 90
 95
 100
%
Tr
a
n
sm
itta
n
ce
 1000   1500   2000   2500   3000   3500  
Wavenumbers (cm-1)
 Figure.4    FTIR spectra of Ag+N Implanted UHMWPE 
 
 
1164,50
1462,89
1471,83
1738,24
BLANK
C+H
 25
 30
 35
 40
 45
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 55
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 80
 85
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 95
 100
 105
%
Tr
a
n
sm
itta
n
ce
 1000   1500   2000   2500   3000   3500  
Wavenumbers (cm-1)
Hydro
xil
 bo
nd
s
C-H
stre
ching  bo
nds
C-O
C
a
rb
o
nil
 g
ro
ups
C=C
D
o
uble
 bo
nd fo
rm
ation
  Figure.5  FTIR spectra of  C+H  Implanted UHMWPE  
 
 
 Increase in the absorption bands in the 800 and 1738.4 cm−1 regions , due to the 
implantation, has been attributed to the creation of unsaturated C=C bonds and carbonyl 
group formations respectively [7] . One of the main products of the ion bombardment is 
the chemical change resulting the C=C  formation, and its stretching vibration is clearly 
−1observed in the spectra by an absorbance peak at 800 cm . The presence of this peak 
suggests that after ion implantation, the polymer surface becomes poor of hydrogen and 
rich of unsaturation which is susceptible to crosslinking and oxidation.  Oxidation causes 
carbonyl groups formation which is observed at around  1740 cm-1. DSC (Differential 
Scanning Calorimeter) was used to measure the energy change of the polymer by 
increasing the temperature in inert N2 gas atmosphere. DSC determines thermal 
properties of the polymer such as  T , ΔH
40,5131.8117.5747.566,1101
C+H+Ar
39,9135.2115.8237.564,269.5
C+H
41140119.673263.474
Ag+N
40137116.524566.430
Ag
39,5141115.075658124
Untreated
Crystallinity
( DSC - % )
Tm
(C0)
∆Hf J/g)Contact Angle( º )Hardness
(Shore-D)
Roughness
(Ra-nm)
Table    gives the contact angle and roughness results together with the other measured properties. It 
seems that the wettability increased with ion implantation and that hidroxil bonds and carbonil bonds have 
dominant effect on wettability
Table 1 .  Over all results
m fus .  ΔHfus is defined as the fusion enthalpy 
which is calculated by taking an integration of  the area of the melting peak. The 
crystallinity of  UHMWPE  (unimplanted and implanted) percentage is shown in table.1, 
tohether  with roughness, hardness, contact angle, ΔHfus  and Tm  . The detailed 
calculation of  the crystallinity  percentage of the polymer could be found in the literature 
[4] . DSC Analysis of  un implanted UHMWPE, Ag and Ag+N, and C+H+Ar and C+H 
ion implanted UHMWPE samples  are shown in figures 6 and 7. 
 
 
 
Table.1 Over all results  
 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure .6. DSC Analysis of  unimplanted UHMWPE, C+H+Ar and C+H ion implanted 
UHMWPE samples. 
 
 
 
 
Figure .7. DSC Analysis of Untreated, Ag and Ag+N Implanted UHMWPE Samples 
 
 
 
 
  
 
5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 4 0 0
-2
0
2
4
6
8
1 0
ΔC p = 0 .4 3
ΔC p = 0 .5 1
T m =  1 3 4 .6  
 ΔC p = 0 .3 7
 
 
 
 
 
 
 
 
 U n tre a te d U H M W P E
 
 A g Im p l.U H M W P E
 T m =  1 3 4 .1  
 A g N Im p l.U H M W P E
H
e
a
t F
lo
w
T e m p e ra tu re  o  C  
T m =  1 3 5 .5 3  
 
 
 
 
 
 
Figure . 8.  TGA curves of the samples of UHMWPE before and after the  ion 
implantation with C+H, C+H+Ar ions. 
 
  
0 100 200 300 400 500 600
1
2
3
4
5
6
1
2
3
4
5
6
497.13
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure . 9.  TGA Analysis of Untreated, Ag and Ag+N Implanted UHMWPE Samples. 
 
 
In TGA results, onset of  degradation starts  for untreated UHMWPE is 251.68 0C. This 
point shifted after irradiation to higher values for  implanted samples (Figures  8, 9). With 
488.77
434.83
445.65
424.16
433.68
 
 untreated
 Ag
 AgN
W
ei
gh
t(m
g)
T (oC)
251.68
267.26
312.69
the same trend total degradation point  424 0C  for untreated UHMWPE sample shifted to 
higher values for  implanted samples.  These results can indicate that the thermal stability 
increased at the surface [8] . Shore-D hardness measurements of unimplanted and 
implanted UHMWPE samples are given in Table.1 , which shows that hardness increases 
with ion implantation . Hardness is purely a relative term and an increase in hardness is 
due to the crosslink formation on the surface [9,10].   It was also observed that  C–H 
bond concentration seemed to be decreasing. This might also indicate that C rich surfaces 
and graphite like structures  occurred, resulting in increased hardness.Contact angle and 
roughness results are given in Table.2 . It seems that the wettability increased with ion 
implantation and that hidroxil bonds and carbonil bonds have dominant effect on 
wettability. Rather low contact values for Ag+N could be due to formation of nitride 
which has an additional effect to oxygen containing groups.   
 
 
 
 
Table.2  Contact angle measurements with water.  
 Figure. 10.  shows the surface topography of unimplanted and implanted UHMWPE 
samples obntained by AFM. As seen from the figure surface roughness decreases with 
ion implantation. This is probably due  to rapid  melting of the polymer surfaces  as a  
result of ion irradiation. High roughness of C+H+Ar implanted UHMWPE surface could 
be due to  Ar ion  sputtering.  
            
          UHMWPE                       Ag implanted                  Ag+N implanted 
 
          
                           
                                                C+H                       C+H+Ar      
Figure. 10.    Surface topography of unimplanted and implanted UHMWPE samples 
obntained by AFM. 
Contact
Angle 
UHMWPE  Ag  Ag + N C+H  C+H+Ar Ti+O Ti+Al+N 
Water  56.2˚  44.8˚  32˚ 37.5  47.5 30˚ 48˚ 
SEM micrographs of  unimplanted, Ag and Ag+N  implanted UHMWPE  surfaces were 
obtained randomly with several measurements are shown in figure 11 . Results represent 
the surface morphology of UHMWPE before and after implantation.  Cracks  on the 
surface are  significantly disappeared after Ag and Ag+N  implantation. Especially, 
cracks were totally disappeared  with Ag implantation. 
     
               (a)                                              (b)                                              (c)       
 
Figure 11.  SEM micrographs of (a) unimplanted, (b) Ag+N implanted and (c) Ag 
implanted UHMWPE samples. 
 
The results proved the Antibacterial effect of  Ag  implanted in UHMWPE, however, the 
measurements should be repeated after the wear tests.   
 
Conclusion 
 
The results indicated that  the chain structure of UHMWPE   were changed and  crosslink 
density increased. There was slight increase in percentage crystallinity but decrease in  
melting point   Tm  with irradiation, which  may be due to  the chain sission of UHMWPE  
since  Tm   is closely related  to number average molecular weight  and also  C=C  double 
bond formation as seen in FTIR  spectra. 
It is believed that slight increase in the crystallinity of the polymer may improve  the 
surface quality of the polymers such as hardness, wear resistance and wettability. 
It was also observed that  C–H bond concentration seemed to be decreasing. This might 
indicate that C rich surfaces and graphite like structures  occurred, resulting in increased 
hardness. It was  observed that nano size cracks (approx.10nm)  significantly  
disappeared   after  Ag   implantation, however less significant with Ag+N implantation . 
This is probably due  to rapid  melting of the polymer surfaces  as a  result of ion 
irradiation, which was also thought to be responsible for decreasing in roughness.   
Contact angle  measurements  showed  that wettability  of samples  increased with ion 
implantation. It is thought that increased in oxygen concentration and formation of 
carbonyl groups were responsible for this. Rather low contact values for Ag+N could be 
due to formation of nitride which has an additional effect to oxygen containing groups.  
Results indicate that metal and metal+gas hybrid  ion implantation could be an effective 
way to improve the surface of UHMWPE  together with antibacterial effect of  Ag 
implantation. 
 
 
 
Acknowledgements 
 
This work was  supported  by  the Center for Irradiation of Materials, Alabama A&M 
University.   
 
 
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