Polystyrene coating is applied to holographic storage tube substrate via glow discharge polymerization in an inert environment. After deposition of styrene coating, antimony and then cesium are added to produce photoemissive layer. Technique is utilized in preparing perfectly organized polymeric films useful as single-crystal membranes

Gange, R. A.

English

NASA Technical Reports Server

December 1972	 B72-10638 
NASA TECH BRIEF 
Marshall Space Flight Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Photoemissive Coating 
A method has been developed of applying a photo-
emissive coating to photoemissive holographic storage 
tubes through the application of a polystyrene coating to 
the substrate via glow discharge polymerization in an inert 
environment. The complex styrene coatings exhibit an 
amorphous structure of approximately 50 A polyciystal-
lite, possess a glass transition temperature of about 146°C, 
and have a melting temperature of approximately 205°C. 
The coatings have a dielectric constant of approximately 6 
and vapor pressures of approximately 10- 1 1 torr at 90°C 
and 5x10 0
 at 150°C. The styrene monomer, with an 
additive for stability, is introduced into a vacuum system 
in an amount such that 100 percent evaporation yields a 
pressure within the system of approximately 0.15 torr 
(150 microns). The pressure is then .increased to 0.5 torr 
(500 microns) by bleeding argon into the system. 
The deformable surfaces upon which the styrene 
coatings are to be deposited are placed between two 
parallel circular stainless steel plates. The energy necessary 
to polymerize and crosslink the styrene monomer is 
supplied by an alternating electric field. To ensure
adequate ionization and surface retention times, it is 
necessary to make electrical contact between the con-
ductive substrate on which the deformable surface rests 
and one of the two circular plates to which the voltage 
source is connected. The arrangement, as illustrated, is 
satisfactory both for routine throughput complex styrene 
coatings and reasonably uniform electrical field distribu-
tions between the conductive substrate and the circular 
plate. A TIC film on a glass plate constitutes the 
conductive substrate. This structure is placed upon a 
gold-plated copper block with a wire connecting the 
substrate and the copper block, which rests upon the 
lower plate. A pressure contact is used to connect the wire 
to the TIC ifim,' and the opposite end of the wire is 
soldered to the gold plated copper block. 
The styrene coating is believed to grow in a macro-
molecular fashion with the entire coating being one large 
molecule. After deposition of the styrene coating onto the 
deformable surface, the entire structure is placed into a 
second vacuum system and the system pumped down to a 
pressure of approximately 10-7 torr. Antimony is added 
Alternating
Electric
Field
Deformable 
Surface
Connecting
Conductive Wire 1	 In. 
Substrate
79n2 J 1 (2.54 cm) Glass Plate 480 VA
0 
Gold Plated_____________ 
Copper Block
1/32 In. 10.08 cm) Stainless Steel Plate-'" 
16 In. 
(4.0 cm)
(continued overleaf) 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use Government nor any person acting on behalf of the United States
	 will be free from privately owned rights. 
https://ntrs.nasa.gov/search.jsp?R=19720000637 2020-03-17T03:41:39+00:00Z
to the system and evaporated at 140°C to the desired 
thickness. Then cesium is added until a peak in photo. 
emissive current is observed. At this point, cesium is 
discontinued, and the 140°C temperature is sustained 
until the observed photoemission is a maximum value. 
The photoemissive cesium-antimony layer has been ob-
served not to react with the complex styrene coating over-
long periods, and the surface appears to be quite stable. 
Notes: 
1. In addition to the obvious application of the technique 
for polymeric coating, information concerning this 
innovation may be useful in the preparation of 
perfectly organized polymeric films that could be 
utilized as single-crystal membranes. These membranes 
would be capable of high selectivity filtration and/or 
separation. 
2. Requests for further information may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Code A&PS-TU 
Marshall Space Flight Center, Alabama 35812 
Reference: B72-10638
Patent status: 
Inquiries concerning rights for the commercial use of 
this invention should be addressed to: 
Patent Counsel 
Marshall Space Flight Center 
Code A&PS-PAT 
Marshall Space Flight Center, Alabama 35812 
Source: R. A. Gange of
RCA Corporation
under contract to
Marshall Space Flight Center
(MFS-22003)
01 
S 
B72.10638	 Category 08


Photoemissive coating

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