A technique for fabricating textured surfaces on polymers without altering their surface chemistries is described. A surface of a fluorocarbon polymer is exposed to a beam of ions to texture it. The polymer which is to be surface-roughened is then cast over the textured surface of the fluorocarbon polymer. After curing, the cast polymer is peeled off the textured fluorocarbon polymer, and the peeled off surface has negative replica of the textured surface. The microscopic surface texture provides large surface areas for adhesive bonding. In cardiovascular prosthesis applications the surfaces are relied on for the development of a thin adherent well nourished thrombus

Banks, B. A.

Sovey, J. S.

Weigand, A. J.

English

NASA Technical Reports Server

United States Patent I191 
Banks et al. 
[111 4,329,385 
[45] May 18, I982 
[54] TEXTURING POLYMER SURFACES BY 
[75] Inventors: Bruce A. Banks, Olmsted Township, 
TRANSFER CASTING 
Cleveland County; Albert J. 
Weigand, Lakewood; James S. 
Sovey, Strongsville, all of Ohio 
[73] Assignee: The United States of America as 
represented by the Administrator of 
the National Aeronautics and Space 
Administration, Washington, D.C. 
[21] Appl. No.: 218,587 
,[22] Filed: Dec. 19, 1980 
[51] Int. Cl.3 ........................ B29D 7/02; C23C 15/00, 
B32B 27/16 
[52] U S .  C1. ................................ 428/141; 204/192 E 
204/192 EC, 264/22; 264/220 
[58] Field of Search .................. 264/22, 220; 428/141; 
204/192 E, 192 EC; 156/643 
1561 References Cited 
U.S. PATENT DOCUMENTS 
2,876,187 3/1959 Wolinski ............................. 204/158 
2,928,131 3/1960 Mahler ................................ 428/141 
3,274,088 9/1966 Wolinski ............................. 204/165 
3,752,731 8/1973 Stiegler et al. ...................... 161/164 
3,761,338 9/1973 Ungar et al. ........................ 156/219 
4,064,030 12/1977 Nakai et al. ......................... 204/192 
4,114,983 9/1978 Maftitt et al. ....................... 350/164 
4,199,650 4/1980 Mirtich et al. ...................... 428/421 
Primary Examiner-Aaron Weisstuch 
Attorney, Agent, or Firm-Gene E. Shook; John R. 
Manning; Norman T. Musial 
2571 ABSTRACT 
This invention is concerned with fabricating textured 
Surfaces on polymers without altering their surface 
chemistries. 
A surface of a fluorocarbon polymer 10 is exposed to a 
beam 12 of ions from a source 14 to texture it. The 
polymer 18 which is to be surface-roughened is then 
cast over the textured surface 20 of the fluorocarbon 
polymer. After curing, the cast polymer is peeled off the 
textured fluorocarbon polymer, and the peeled off sur- 
face 22 has a negative replica of the textured surface 20. 
The microscopic surface texture provides large surface 
areas for adhesive bonding. In cardiovascular prosthesis 
applications the surfaces are relied on for the develop- 
ment of a thin adherent well nourished thrombus. 
7 Claims, 3 Drawing Figures 
IO 
https://ntrs.nasa.gov/search.jsp?R=19820020564 2020-03-21T17:12:01+00:00Z
U.S. Patent May 11, 1982 
FIG. I 
h o  
FIG. 2 
4,329,38 
IO 
FIG. 3 
1 2 
Kn enlarged sectional view showing a poly- 
FIG. 3 is an enlarged sectional view similar to FIG. 2 
TEXTURING POL BY er a textured fluorocarbon polymer; and 
showing the surface roughen 
ORIGIN OF THE INVENTION 5 from the textured fluorocarb 
The invention described herein was made by employ- 
ees of the United States Government and may be manu- 
factured and used by or for the Government fo’r govern- 
mental purposes without the payment of any royalties 
thereon or thereto. 
TECHNICAL FIELD 
BEST MODE FOR CARRYING OUT THE 
INVENTION 
Referring now to the drawings, there is shown in 
fluorocarbon polymer 10 that is expoved to a 
f ions in a manner described in U.S. Pat. No. 
4,199,650. This beam 12 is nreferably from an electron 
bombardment ion source 14 of the type developed from This invention relates to a method of fabricating tex- electric propulsion technology. Such an ion source is 
described in “Advances in Electronics and Electron tured surfaces. The invention is particularly concerned 15 
Physics” by H. R. Kaufman, vol. 36, pages 365-373. with imparting a microscopic surface texture to poly- 
Beam extraction is accomplished by a dished, two-grid mers without altering their surface chemistries. 
ion optics system 16. Such‘a system is described in on the polymer pro- 
AIAA paper No. 76-1017 entitled “A 30 cm Diameter vides large surface areas for a ve bonding and paint adhesion. In cardiovascular prosthesis applications the 20 Argon Ion Source,,. Neutralization of the ion beam 12 
adherent, well nourished thrombus with t6e potential bombardment of the vacuum facility walls or by use of 
a neutralizer. for reduced occurrence of thromboembolism. 
The microscopic surface tex 
surfaces are On for the Of a thin, can be achieved by secondary electrons released by ion 
LJ 
A roughened base or master is coated with a strippa- 
ble plastic material for transferring the surface rough- 
ness pattern to a plastic coating in prior art processes. 
Such methods are taught in Mafftt et a1 U.S. Pat. No. 
4,114,983, Stiegler et a1 U.S. Pat. No. 3,752,731 and 30 
Mahler U.S. Pat. No. 2,928,13 1. 
Radiation treatments of plastic films also have been 
suggested in the prior art. These treatments are relied 
on to enhance the adhesion properties of the material. 
Such treatments are disclosed in Nakai et a1 U.S. Pat. 35 
No. 4,064,030 and Wolinski U.S. Pat. No. 2,876,187 and 
3,274,088. Other methods used to provide microscopi- 
cally rough polymeric surfaces include salt particle 
dispersion casting and mechanical abrasion. 
Certain disadvantages are inherent with these prior 
art methods. These disadvantages include an excessive 
thickness of the texture, inadequate uniformity of the 
texture, and the altering of the surface chemistries. 
40 
BACKGROUNDART *c The electron bombardment ion source 14 is located in 
a vacuum facility which is sufficiently large to minimize 
back sputtered facility material from contaminating the 
flurocarbon polymer. The vacuum facility is maintained 
at a pressure of about 4>( 10-5 torr during the operation 
of the ion source. 
The fluorocarbon polymer is positioned normal to 
the ion beam 12 at a location of about 20 centimeters 
from the ion source 14. The current density is between 
about 0.5 mA/cm2 and 1.0 mA/cm*. The beam 12 is 
uniform over the surface of the fluorocarbon polymer 
10, and has an energy in the 200 eV to 2000 eV range. 
Among the fluorocarbon polymers that have been sput- 
ter-textured in this manner are polytetrafluoroethylene 
and fluoroethylene propylene. It is also contemplated 
that other fluorocarbon polymers can be used for ion 
beam texturing. Among these are polymers known 
commercially as PTFE Teflon, FEP Teflon, PFA Tef- 
lon, and Tefzel. 
As shown in FIG. 2 a polymer 18 which is to be 
45 surface-roughened is then cast over the textured fluoro- 
carbon polymer 10 after the fluorocarbon polymer has DISCLOSURE O F  INVENTION 
The method of the present invention utilizes ion beam been textured and removed from the vacuum facility. A 
sputtering for texturing the surface of a fluorocarbon wide variety of polymers can be cast over the textured 
polymer. The ion beam sputter textured surface is a fluorocarbon polymers. 
microscopically rough texture resulting from spatial 50 Among the polymers which can be cast over the 
differences in sputter yield of the quasi crystalline fluo- fluorocarbon polymers are silicone rubbers, polyure- 
rocarbon polymer. The textured surface also may be thanes, and polyolefins. It is further contemplated that 
formed by sputter etching through a mesh or mask that other low elastic modulus polymers can be used as the 
produces an organized array of surface pits. Addition- casting polymers. 
ally, the textured surface may be formed by sputter 55 The cast and cured polymer 18 is then peeled off the 
etching through a disbursed fine particulate covering textured fluorocarbon polymer 10 as shown in FIG. 3. 
the fluropolymer. The nonstick fluoropolymer surfaces 20 aid in the re- 
The polymer to be surface roughened is cast over the moval of the cast polymer 18 and its separation from the 
textured surface of the flurocarbon polymer. The cast fluorocarbon polymer. The peeled off surface 22 of the 
and cured polymer is then separated from the surface of 60 cast polymer then has a negative replica of the textured 
the textured flurocarbon uolvmer. fluorocarbon uolymer surface 20. - -  
While a preferred embodiment of the invention has 
been described, it is contemplated that various rnodifi- DESCRIPT1oN OF THE 
Details of the invention will be described in connec- 
tion with the accompanying drawings wherein; 
FIG. 1 is a schematic view of the ion beam texturing 
apparatus used to prepare the surfaces of the fluorocar- 
bon polymers; 
cations may be made without departing from the spirit 
65 of the invention or the scope of the subjoined claims. By 
way of example, various inorganic, organic, non-metal- 
lic and metallic ion beam textured substrates can be used 
for the negative casting by sputtering a thin fluorocar- 
4,329,385 
3 4 
bon polymer coating over the texture to allow release of 
the cast polymer. ronment, and 
providing a source of argon ions in said vacuum envi- 
positioning said fluorocarbon polymer in the beam of 
argon ions at a location of about 20 centimeters 
from said source, said at least one surface being 
substantially normal to said beam. 
3. A method of texturing the surface of a polymer as 
claimed in claim 2 wherein the argon ion beam is sub- 
stantially uniform over said at least one surface. 
4. A method of texturing the surface of a polymer as 
claimed in claim 1 wherein the fluorocarbon polymer is 
first sputtered onto a substrate. 
5. A method of texturing the surface of a polymer as 
claimed in claim 1 wherein said polymer is selected 
15 from the group consisting of silicone rubbers, polyure- 
thanes, and polyolefins. 
6. A method of texturing the surface of a polymer as 
claimed in claim 1 including the step of applying a re- 
lease agent to said textured surface prior to casting said 
7. A polymer article textured according to the pro- 
We claim: 
1. A method for texturing the surfaces of a polymer 
without altering the chemistry of the same comprising 5 
the steps of 
placing a fluorocarbon polymer in a vacuum environ- 
ment of about 4x 10-5 tort, 
exposing at least one surface of said fluorocarbon 
polymer to a neutralized beam of ions having an 10 
energy between about 200 eV and 2000 eV and an 
ion beam current density between 0.5 mA/cm2 and 
1.0 mA/cm* to texture the same, 
removing said fluorocarbon polymer from said vac- 
uum environment, 
casting a polymer over said textured surface of said 
fluorocarbon polymer and curing the same, and 
separating said cast and cured polymer from said 
fluorocarbon polymer whereby the surface of said 
polymer has a negative replica of said textured 20 polymer over the same. 
surface of said fluorocarbon polymer. 
2. A method of texturing the surface of a polymer as cess of claim 1. 
claimed in claim 1 including * * * * *  
25 
30 
35 
40 
45 
50 
55 
L 
65 


Texturing polymer surfaces by transfer casting

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